Category: hydroponic agriculture

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The subsistence technology type that has probably sparked the most controversy is hunter-gatherers

Imagine that an STI which leads to infertility occurs in the female population with probability k. Then, an uninfected man and his wives can avoid infertility if and only if none of his wives have the infection. This occurs with probability: n . If we assume an empirically plausible rate for this STI, like 0.07 , then a monogamous man would be paired with fertile woman 0.93 of the time, and a man in 2-polygyny would be paired with fertile women 0.86 of the time. An ultra-wealthy man in 10-polygyny, however, would be more likely than not to have infertile wives—a prospect that could lead to diminishing fitness returns to, and hence, demand for, additional wives. A similar argument holds even if marriage is considered sequentially—as in serial monogamy—though the effect would be smaller. Finally, impediments to cooperation or even outright conflict among co-wives can be greater as the number of wives increases. Interference competition among co-wives could impose significant fitness costs in settings where effective child rearing benefits from cooperation. It could well be that incumbent wives resist incorporation of additional wives to the wealth sharing pool, perhaps with greater effectiveness as their numbers grow. Empirically exploring these and other possible explanations for the unexpectedly substantial diminishing fitness returns to additional wives that are not explainable by the division of rival wealth among wives would be a valuable next step, but one that would take us beyond the formal modelling, database and comparative statistical methods that we have presented.Recent anthropological research on the causes of war falls roughly into two schools : one which concludes that sociopolitical factors are the primary determinants of war ,large plastic pots and another which argues that environmental and technological factors are primary . Both “schools” have developed testable hypotheses about the conditions making a society more likely to go to war .

In this study we retest two hypotheses initially tested by Nolan : first, more productive subsistence technology leads to more war; and second, higher population density leads to more war. Both hypotheses come from ecological-evolutionary theory, which asserts that subsistence technology is the single most important factor affecting how societies are organized and how they interact with one another . Ecological evolutionary theory predicts warfare is more frequent in societies with more productive subsistence technology for three main reasons. First, armies need to eat; a society with unproductive subsistence technology would not have the food stock to sustain soldiers in a prolonged conflict. Second, food stores make for attractive targets; hence, societies with more productive subsistence technology are more likely to be attacked. And third, fixed investments in fields and structures give a society with more productive subsistence technology a strong incentive to defend its territory from attackers.Some have claimed that, compared to other societies, hunter-gatherers are relatively peaceful while others disagree . Ecological-evolutionary theorists tend towards the ‘relatively peaceful’ side of the debate. Nolan , for example, argues that hunter-gatherers usually lack the resources to sustain them during long periods of warfare. Likewise, they have little to be plundered and find it feasible to walk away from a confrontation and move to a new area. Ecological-evolutionary theorists expect the frequency of warfare to be higher among horticulturalists than among hunter-gatherers. Horticulturalists own more resources than hunting-gathering societies, and are more attractive targets. While hunter gatherers can with relative ease walk away from an attack and move to a new location , horticulturalists are more likely to defend their lands and structures . And since metal tools make horticulturalists more productive, and metal weapons make warriors more deadly, horticulturalists are expected to have even higher rates of warfare if they have learned to use metal .

Slavery has a similar effect in increasing the frequency of war: armies can capture slaves, which can then be used to produce food, which can be used to feed armies, which can then capture more slaves – thus creating a positive feedback warfare-slavery system . Ecological-evolutionary theorists expect plow agriculturalists to have even higher frequencies of external warfare than horticulturalists , since they have more productive subsistence technology, which compounds the warfare incentives affecting horticulturalists. Agrarians are even more reliant on their land than horticulturalists and therefore even less likely to walk away from a confrontation; they can produce even larger and more diverse food stores – further incentivizing plunderers; their larger food stores can feed larger armies; and slavery becomes even more profitable as more productive technology increases the returns to labor. For these reasons, most previous studies of the ecological-evolutionary theory of warfare have supported the idea that as subsistence technology becomes more productive, the frequency of warfare increases. The hypothesis of a positive correlation between population density and warfare is based upon the notion that, within a given subsistence technology type, increases in population density will increase the pressure on a society’s resources, thus motivating a society to plunder the resources and conqueror the arable lands of its neighbors. Hence, some studies maintain that the frequency of warfare will increase as population density increases. Other studies argue for a cubic relationship – claiming that warfare increases, decreases, and finally increases again across categories of increasing population density. In his study of precontact Polynesia, Younger finds a negative relationship between population density and violence. Thus, there is by no means a consensus within the literature about this relationship. In a 2003 paper published in Sociological Theory, Patrick D. Nolan sets out to test whether certain modes of subsistence are “structurally conducive” to warfare . Using variables from the Standard Cross-Cultural Sample , Nolan produces a number of contingency tables, examining whether the frequency of warfare varies across four subsistence modes and by population density.

He finds that societies with advanced horticulture or agrarian subsistence engage in warfare much more frequently than those with foraging or simple horticulture. He also finds that high population densities are associated with more war in societies with foraging or agrarian subsistence, but not in those with horticulture. While we find much of value in Nolan’s theoretical discussion, there are serious problems with his empirical analysis. First, in adopting a contingency table approach, Nolan chooses a method that requires reducing the variation found in the original SCCS variables, in order to have relatively few cells in each table. Thus he takes a measure of frequency of warfare , available in the SCCS with 18 discrete values, and turns it into a dummy variable, with only two discrete values. Likewise, he employs only four general subsistence categories, a feat he manages by lumping hunting with gathering, and discarding 54 of the 186 SCCS societies that subsist as mounted hunters, fishers, pastoralists, or rely equally on two or more subsistence modes . Particularly problematic is the removal of relatively warlike pastoralists and mounted hunters from his sample. Table 1 compares Nolan’s categories with the categories given in SCCS v858. The four subsistence taxonomies presented in the SCCS provide much richer detail: variable v246 has seven categories; variable v833 has eight; variable v858 has 11; and combining variables v833and v834gives 28 categories. But even more variation can be found by using variables v814–v819, which provide actual ordinal measures of the percentage dependence on each category of agriculture, domestic animals, fishing, hunting, gathering, and trade. Variation is the great friend of any statistical analysis, and the SCCS contains variables that provide abundant variation on subsistence technology. That Nolan reformulates his variables to reduce variation is due simply to his choice of technique— contingency tables work well only when there are relatively few cells in the table. Contingency tables also limit the analysis to pairwise relationships between variables, and at best can be modified to fit a three-way relationship. When there are confounding variables, as there always are,plastic pots for plants the results from a pairwise analysis will be biased. It is on this count that multivariate models provide their greatest advantage: one can control for the effects of other variables and thus produce unbiased estimates. And because multivariate methods consider a large set of variables, one can gain a sense of how important a particular relationship is in the grander scheme of things. Galton’s problem—the confounding effect of cultural transmission—is a major methodological issue in empirical studies using cross-cultural survey data. There are no effective ways to control for Galton’s problem within a contingency table framework and Nolan wisely does not try. Dow has developed an effective way of modeling Galton’s problem within a multivariate model framework, which provides yet another advantage to multivariate methods over contingency tables. Finally, there is the problem of missing data. As shown by Dow and Eff , dropping observations for which data values are missing can lead to bias, even within a multivariate modeling context. Nolan dropped observations that were not even missing—removing 54 societies that did not fit neatly into his subsistence taxonomy categories .

The appropriate way to handle missing data is the technique of multiple imputation . Nolan’s empirical work does not do justice to his theoretical discussion. In what follows, we investigate the role of subsistence technology and population density in causing war, using contemporary best-practice statistical methods. Wealth accumulation provides the means for elites to enhance their status, and this status-enhancement strategy is both an alternative to the strategy of war and can be disrupted by war, making war less attractive to elites. SCCS variable v17 was included as a scale for the use of money and credit. Small communities are less likely to have powerful elites , and are therefore less likely to be driven by elites to war. In fact, Younger’s study of Polynesian war found that smaller communities were more peaceful. We therefore include a scale for community size . Elites will also be less able to drive a society to external war when their power is less secure; variable v575 was included as an “unstable political power index.” If local political structures are complex, elite power may be fragmented, and it may be difficult for all relevant actors to agree upon a course of action, which would make war less frequent. For this reason, v236, a measure of the number of levels in the jurisdictional hierarchy of the local community, is included. Similarly, we introduce variable v757, which measures whether political authority is simultaneously religious authority, reasoning that more heterogeneous elites are less likely to find common cause in external war. Military historians speak of the three “C’s” in the analysis of war: causes, conduct, and consequences . Our analysis focuses on the causes of war, but features of a society facilitating its conduct will also serve to make a society more likely to go to war, and in this way the feature can be seen as a cause. For example, when females contribute a great deal to subsistence, the opportunity cost of sending a man to war is lower, and the choice of war therefore is less costly. For this reason, we include variable v826, “average female contribution to subsistence.” Certain kinds of technology facilitate the conduct of war. For example, the development of metal weapons makes warfare more practicable and increases its incidence . Thus, we create the variable metal as the composite for four SCCS variables concerning the use of metal tools and weapons.4 Similarly, Nolan notes that limited communications and transportation technology “were the only real constraints” horticulturalists faced in using war to control more land and subject peoples. We employ here v149, which measures the degree to which a society utilizes writing and records. A prior study by Brown and Eff found the frequency of external warfare and the presence of moralizing gods to be inversely related; suggesting that morality reinforced by supernatural forces may serve to constrain warlike behavior. We investigate this by including SCCS variable v238 in our model. The bottom panel in Figure 3 plots the total effect on the ordinate and pdens on the abscissa. Since pdens is standardized, the total effect will be positive for societies with below-mean population density, and negative for societies with above-mean population density. The resulting plot is nearly linear—fitting a negatively sloped straight line with an R 2 of 0.796. Our model’s negative relationship between population density and the frequency of war is consistent with Younger’s findings but not those of Nolan or Keeley .

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Fruit were harvested from healthy and HLBaffected trees

Volatiles that signal the presence of flush may be important components in scent lures. Flushing shoots are essential for ACP reproduction. Signature odors might include cuticular hydrocarbons, ammonia, methanol, and carbon dioxide, all of which are emitted during leaf expansion. These compounds may synergize ACP response to terpenes emitted by foliar scent glands. Sesquiterpenes may be important signal compounds. These terpenes are prevalent in the aromas of ‘super hosts’ but most are commercially unobtainable; little is known about their effect on psyllid attraction. A better understanding of these factors could lead to the development of scent lures that are consistently effective in a variety of application situations. Better monitoring tools would especially be useful where ACP population densities are low or for tracking psyllid movement patterns. Citrus groves receiving nutritional sprays to manage HLB were compared with groves in the same areas receiving conventional fertilization treatments.In 2009–2012, HLB fruit were sorted into symptomatic and asymptomatic , while later , no distinction was made between symptomatic and asymptomatic HLB fruit. Fruit were washed and juiced using JBT extractors and finishers, then pasteurized following industry standards. Sensory tests were performed with trained and untrained panelists. In 2009–2010, differences between juice from healthy and HLBa fruit were minimal, and only perceived by trained panelists. Juice from HLBs was off-flavored, bitter, sour, with some metallic, tingling, and umami taste. These descriptors were mostly used for early season Hamlin,macetas 5 litros while the effect of HLB on Valencia juice flavor was minimal. Nutritional treatments had no consistent effects on juice flavor over the 5-year duration of the study.

Difference-from-control tests showed improvements due to nutritional treatments on Hamlin in January 2012, December 2012, and January 2013, i.e., panelists could not detect differences between juice from healthy and HLB fruit. Trained panelists found more differences between juice from healthy and HLB fruit than between juice from different nutritional treatments, except for one Hamlin nutritional juice in December 2012. Blends made with 75:25, 50:50, and 25:75 ratio of healthy and HLB Hamlin juice were also tested. Trained panelists classified the 75:25 blend with healthy juice, and 25:75 with HLB juice, confirming previous blending studies, while the flavor of the 50:50 blend varied with harvest. In conclusion, no management practice in the field was able to alleviate the effect of HLB on juice flavor. However, much of the off-flavor depended on the season and levels of sugars, acids, and other components in the juice. The Asian citrus psyllid was detected in California in October 2008 and has invaded most of the citrus grown in southern California. Huanglongbing was detected in Los Angeles County in 2012 and poses a significant threat to California’s ~$2 billion citrus industry. Establishment of ACP and HLB can cause huge economic loss and it is important to slow the spread of the HLB pathogen. At present, this can best be achieved by controlling the size and spread of psyllid population through integrated management strategies. A series of lab trials were conducted to evaluate the residual efficacy of various conventional and organic chemicals for ACP control and for selection of chemicals that were least toxic to natural enemies like Tamarixia radiata. The most persistent organic insecticide tested was Entrust + oil and to a lesser extent Trilogy. Among four pyrethroids, Danitol was most effective and persistent, while Mustang was weaker when tested with adult ACP. However, when toxicity was tested with adult Tamarixia, both the organic and conventional pesticides were not as toxic as they were to ACP adults. In a separate study, a field trial was conducted to test the efficacy of organic insecticides against ACP nymphs. Among the materials tested, Entrust + oil provided better control in comparison to two other products.

Future plans include further trials under lab and field conditions to evaluate products for ACP control that are least toxic to natural enemies.The Asian citrus psyllid vectors pathogens that cause Huanglongbing or citrus greening disease. Management of ACP is critical in all habitats including organic citrus for area-wide suppression of HLB. Mature citrus trees in Florida go through dormancy in winter producing little or no new growth required for ACP to develop and reproduce. Targeting overwintering ACP adults with sprays of broad-spectrum insecticides has been shown to provide significant reduction into growing season and opportunity for biological control and selective insecticides. This tactic is adopted area-wide in Florida and Texas and also used in California. However, organic farmers struggle with management of ACP and HLB because they cannot use synthetic insecticides. Consequently, we have initiated development of ACP control programs testing use of organic insecticides and release of Tamarixia radiata also suitable for conventional citrus and urban habitats. We evaluated dormant winter sprays of an organic insecticide, Pyganic applied in November, December, and January compared to a single spray of the synthetic pyrethroid Danitol in January against ACP in Valencia and Hamlin oranges. Pyganic was applied either alone, with horticultural mineral oil , or soybean oil at 2% volume by volume. Significant effects of Pyganic plus either oil lasted for 1–2 weeks after November and December applications. Pyganic + HMO and Danitol maintained ACP at or below 0.1 adults per tap sample for 4–5 weeks, and significant suppression lasted 2 months after the January application. Monthly applications of Pyganic with HMO appear to be a reasonable option for organic growers to suppress overwintering ACP. Organic programs evaluating promising insecticides alone or altered with oils or other surfactants are being evaluated parallel to a conventional program. Tamarixia radiata are also being released for integration in these programs. Findings and implications for ACP management will be discussed. Tolerance, or resistance, to citrus Huanglongbing will be important as a long-term solution for this disease. In a field trial conducted with over 1000 plants belonging to different genera in the sub-family Aurantioideae, we observed field tolerance in many Australian citrus relatives. To confirm these results in a controlled greenhouse setting, we have exposed 140 plants to Candidatus Liberibacter asiaticus via psyllid feeding under no-choice conditions for a period of 2 weeks.

We have maintained these seedlings under greenhouse conditions and conducted detailed analysis on the presence of the pathogen and level of tolerance observed in various plants after exposure to the pathogen. We have analyzed the samples using qPCR and droplet digital PCR to estimate the bacterial titer in accessions that were either susceptible, tolerant, or resistant in field studies. To confirm the presence or absence of the pathogen in plants with questionable qPCR results, ddPCR analysis was conducted targeting multiple genomic regions of Candidatus Liberibacter asiaticus. Since these experiments are conducted using open pollinated seeds where the pollen parent is not known, we have also conducted about 2000 pollinations using Microcitrus, Eremocitrus, pummelo, and mandarin as both seed and pollen parents. The targeted crosses were also conducted with known HLB tolerant cultivars of mandarins like Temple tangor and Fallglo mandarin. Citrus greening, also known as Huanglongbing , is a devastating disease on Citrus plants and is caused by the yet unculturable bacterial Candidatus liberibacter spp. This gram-negative bacterium is limited to vascular tissue and mainly accumulates in the symplasm of autotrophic organs. In addition, the accurate quantification of viable bacteria is necessary to assess the status of potentially-infected trees as well as to test any possible control strategies. A number of methods have been broadly described to quantify total bacteria content; which includes the detection of both live and dead bacteria as well as the different bacterial pathovars. In the present work,macetas de 30 litros an improved detection method, based on PCR is described, which employs new designed primers. Real-time PCR was also employed to test the sensitivity of the method, which was able to detect 10 copies per genome in tree-infected trees. In addition, Droplet Digital PCR was also developed to detect two copies per plant genome, which is the highest sensitivity reached in current protocols. The accuracy of the tested techniques will allow assessing the feasibility of possible controlling methods of this devastating disease. Researchers have been exploring more effective ways to control the Asian Citrus Psyllid , the only known insect vector of the phloem-limited bacterium “Candidatus Liberibacter sp.” responsible for Citrus Greening or Huanglongbing disease. Research results are reported on the use of a crowd sourcing challenge-based strategy to identify gene targets in the ACP that can function as interdiction points to control the insect using an oral uptake RNA interference strategy. This challenge was sponsored and developed by the Florida citrus industry and posted on the web through Innocentive, Inc. Interested participants were allowed to submit suggested targets with justifications for orally administered dsRNAs that would be hypothesized to induce mortality by RNAi. Of the sequences submitted, a committee of experts selected 43 for an oral uptake bio-assay performed using an artificial diet screen to identify those that induced mortality. Subsequently, a citrus phloem-limited virus vector was used to engineer citrus to produce candidate dsRNAs in the phloem. When ACP fed on these plants, there was much greater ACP mortality than was observed by artificial diet delivery, in some cases producing 100% adult ACP mortality in detached-leaf bioassays.

RNA Seq analysis shows that resulting ACP transcriptome changes were attributable to genes functionally linked to the gene targeted by RNAi. New methods are needed to control the spread of the citrus greening pathogen, Candidatus Liberibacter asiaticus , by the Asian Citrus Psyllid . This collaborative project funded by the California Citrus Research Board is focused on discovery of protein-protein interactions involved in Huanglongbing transmission. During transmission of CLas within the ACP, interactions between the vector and host regulate how the pathogen moves through the insect, replicates, and is transmitted into a plant. In this study, Protein Interaction Reporter technology has been used to characterize protein interactions between CLas and ACP. The PIR strategy was developed by the Bruce Lab and uses novel crosslinker molecules which covalently link interacting proteins. Mass spectrometric analysis of PIR cross-linked peptides provides information on the relative proximity and orientation of surface exposed lysine residues in cross-linked protein complexes. The Bruce and Cilia labs have previously successfully applied PIR technology to study interactions with an aphid-transmitted virus. Percoll density gradient centrifugation has been applied to purify enriched populations of CLas cells from infected ACP. Using this method, intact CLas cells retaining interactions with ACP tissues are recovered. Infected psyllids were homogenized in a non-denaturing buffer, and the concentrated lysate was applied to a Percoll gradient. Centrifugation resulted in two distinct bands in the Percoll gradient—these fractions were recovered, the cells were washed, and qPCR was used to quantitate the amount of CLas cells present. The PIR cross-linker was used to capture protein interactions in the enriched CLas sample, and the cross-linked peptides were subjected to mass spectrometry analysis. Given the challenges of working with this non-culturable pathogen, this Percoll method for CLas enrichment has a range of potential applications, including the use of purified CLas cells as immunogen for antibody production.Huanglongbing is the most serious recent threat to the US citrus industry. Several studies have indicated that Poncirus is resistant to HLB, but the Poncirus genes for HLB resistance are to be identified and characterized. The Ctv locus in Poncirus confers durable broad-spectrum resistance to citrus tristeza virus , a virus that is phloem-limited like CLas, has been identified and sequenced. We compared the genomic organization of the Ctv region to the corresponding regions from three susceptible citrus species and analyzed the genes, particularly the resistance genes within the locus, in an attempt to gain perspective of the to-be-identified HLB resistance gene in Poncirus. Copy number and localization of R-genes at the Ctv and ctv regions vary considerably from species to species; R-genes have been on faster paces of sequence change than surrounding genes. Dramatic structural rearrangements have occurred, resulting in an expansion of ~60 kb at the Ctv region over the ctv region. While the center of the Ctv region is packed with a rich and diverse group of retrotransposable elements , the ctv regions are free of REs. Pondering these phenomena at Ctv, it is intriguing to speculate the likely structure and evolution of the Poncirus genomic regions harboring HLB resistance genes.Huanglongbing is the most devastating disease of citrus.

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It is less clear what happens when a very similar product is removed from the market for safety reasons

All visible bands were assigned a number based upon relative position to the DNA ladder. Each position was then assigned a “0” or a”1” to indicate absence or presence of the band, respectively. The 0/1 matrix was then used to generate the dendrograms. Similarities based on the Dice coefficient were calculated and UPGMA clustering was obtained using NTSYS software . The comparative cluster analysis of different strains integrates banding pattern data from two separate experiments. The data were combined in a single matrix. Although banding patterns differed there were some band positions in common in some strains across the two studies. The reagents used in the two studies were identical; however the PCR thermal cycler was different, a GeneAmp PCR System 2700 was used in this study. In a previous study 349 strains isolated from different native fermentations in China were screened by interdelta sequence typing. The number of strains tested in this analysis did not allow definitive comparisons of highly similar strains as each strain was only run once. However based on this preliminary analysis 54 different banding patterns were identified. These 54 strains were studied in more detail under conditions enabling conclusive comparisons of DNA band profile. Samples of the strains were run on gels multiple times and band positions calculated in comparison to the DNA ladder on each gel. Strains were run on different gels and yielded identical patterns on the replicate gels. This method generated stable replicate banding patterns for each isolate. The replicated interdelta sequence typing methodology enabled clear differentiation of forty-two distinct S. cerevisiae genotypes among the 54 S. Twenty-one strains of S. cerevisiae isolated from Xinjiang revealed eighteen different patterns . The analysis of thirty-three S. cerevisiae isolates from Ningxia revealed the existence of twenty-four distinct profiles in other words, 24 differentiated strains. The results also showed that the interdelta profile of genotype NX10 was identical to that of commercial yeast Lalvin RC212,maceta 5 litros which has been used in this region as a commercial starter strain.

In general, the Xinjiang and Ningxia regions evaluated in this study exhibited different S. cerevisiae populations. There were no identical strains between the regions. In addition, comparison with the forty-four interdelta genetic patterns found among the fifty-two Saccharomyces strains from Liu et al. revealed that no identical strains were present between the studies. The PCR amplification profiles obtained by interdelta sequence typing were used to obtain independent presence-absence matrices for S. cerevisiae isolates from Xinjiang and Ningxia, China. The dendrograms deduced by interdelta sequence typing are presented in Figures 3 and 4, respectively. The dendrograms demonstrated that native wine fermentations were conducted by a mixture of S. cerevisiae strains. In general a minimum of two interdelta sequence profiles could be detected during each of the spontaneous fermentations with the exception of the fermentation of Big-berry Thompson Seedless. Some strains showed highly similar but not identical banding patterns and are thought to represent genetically related strains. Six clusters of two isolates each, cluster XJ4 and XJ5, XJ12 and XJ15, XJ2 and XJ7 ; NX2 andNX3, NX29 and NX33, and NX9 and NX32 showed highly conserved interdelta sequence patterns indicating that they are likely genetically distinct derivatives of the same strain. Two clusters of four isolates, cluster NX1, NX4, NX5, and NX8; cluster NX17, NX30, NX31, and NX26 also displayed conserved interdelta sequencing patterns again suggesting a genetic relationship among the sets of strains. The S. cerevisiae isolates from Xinjiang that clustered together were from the same grape variety, but, in contrast, the isolates from Ningxia that clustered together were from more than two different grape varieties. NX10 from a native Riesling fermentation was indistinguishable from the commercial strain RC212. A difference was observed in the genetic relationships of S. cerevisiae among strains isolated from table and wine grape varieties planted in Xinjiang . Both table and wine grapes are used for wine production in Xinjiang. Four groups containing nine, eight, three, and one isolate, respectively, were distinguished with a Dice coefficient of 0.448. All nine isolates in group I and all the 3 isolates in group III were obtained from the table grape varieties Red Globe, Small-berry Thompson Seedless, Big-berry Thompson Seedless, and Mixed white . Group II had seven isolates from wine grape varieties of Merlot and Mixed red , and one isolate from the table grape variety Red Globe.

Group IV only included one genotype, XJ3, also from Red Globe . Thus the majority of isolates from the four different table grape fermentations were genetically similar in banding pattern and clustered together. In addition, a difference was observed in the genetic relationships of S. cerevisiae among strains isolated from red and white wine grape varieties planted in Ningxia . Five groups are indicated in Figure 4, when the Dice coefficient is 0.674. Groups I, II, and III consisted of isolates from more than three grapes varieties, while group V only included isolates from Pinot Noir. Group IV included only 1 isolate, NX20, from Cabernet Sauvignon. Most of the S. cerevisiae isolates included in group I were isolated from red grape varieties , while isolates in group III were mainly from white grape varieties . All the isolates in group II were from the red grape varieties of Cabernet Sauvignon, Merlot, and Cinsault . Genetic relatedness was also evaluated by constructing a dendrogram compiled from all interdelta sequence patterns in this study and Liu et al. . Differences were observed in the genetic relationships between the Chinese strains and the strains from the UC Davis collection. The similarity of strains was correlated with their geographical regions of origin: Ningxia strains were closer to the Xinjiang strains, while a clear separation between the indigenous Chinese and the UC Davis strains was observed. The dendrogram produced by interdelta sequence typing revealed five groups containing fifty-one, four, forty-eight, three, and one isolate each when the Dice coefficient is 0.418 . The largest group, group I, contained fifty isolates from China and one from California . There is a difference observed in the genetic relatedness between Xinjiang and Ningxia indigenous S. cerevisiae strains. Group I could be further divided into five subgroups, I-1 to I-5, when the Dice coefficient is 0.506. Most of the S. cerevisiae isolates included in subgroups I-1 and I-5 as well as all three in I-4 were isolated from Xinjiang, while isolates in I-3 and I-2 were mainly from Ningxia . Group II displayed a high similarity with XJ19 , UCD587 , UCD2515 and UCD2516 . Forty-eight out of fifty-two Saccharomyces isolates from the UC Davis collection were clustered in group III. XJ2, XJ7, and XJ20 were clustered in group IV. Group V consisted only of XJ3. Clusters IV and V containing XJ2, XJ7, XJ20, and XJ3 had a low degree of similarity with other Chinese indigenous genotypes and UC Davis collection strains . In addition,cultivo de la frambuesa this dendrogram showed that identical isolates were found only in the same geographic regions with the exception of UCD522 and UCD514 . Understanding the genetic diversity of S. cerevisiae strains from different geographical origins can make an important contribution towards delineating the genetic distance of these strains as well as providing genetic material for further strain development. The genetic diversity of indigenous S. cerevisiae was investigated during the spontaneous fermentations of grape must in Xinjiang and Ningxia, China. Eighteen distinct interdelta profiles were found in Xinjiang, and twenty-four in Ningxia. Forty-two different S. cerevisiae strains were distinguished out of a total of three hundred and forty nine isolates analyzed. All forty-two of these isolates were unique when compared to a set of strains from other major international wine producing regions . Lavin RC212, showing the same interdelta sequence patterns as genotype NX10 isolated from Ningxia was detected during the spontaneous fermentations in this study. Similar to other studies, commercial yeasts were detected in fermentations without inoculation . In this study, the detection of Lavin RC212 colonizing a spontaneous fermentation could be explained by the winery practice of dumping grape skins on the road for drying. Valero et al. analyzed the dissemination and survival of commercial wine yeast in the vineyards near wineries and they suggested that the dispersion of commercial strains is mainly mediated by water run-off and derived from macerated grape skin at dumping sites. Drying the grape skins on the roads for further processing is a normal practice at the Imperial Horse Winery, Qing Tongxia, Ningxia, China, where the spontaneous fermentations were conducted.

It is understandable that this practice could have contributed to the dissemination and survival of Lavin RC212 in the vineyards and wineries, and its occurrence in spontaneous fermentations. In this study, comparison between eighteen and twenty-four different S. cerevisiae patterns by interdelta sequence typing revealed that yeast strains from Xinjiang and Ningxia did not share the same interdelta profiles. The same observations made in the Western Cape, South Africa showed that different S. cerevisiae strains were present at different regions in the different climate zones. In addition, the differences could be attributed to the fact that the grape varieties studied were different in these two regions: table and wine grape varieties in Xinjiang vs. wine grape varieties in Ningxia. This result agrees with a previous study that demonstrated the impact of grape variety on yeast diversity . Further, this study suggests that these two wine making regions are biologically isolated from each other. Geographic location and ecological niches are both thought to play a significant role in Saccharomyces strain diversity . In comparison with strains isolated from other wine making regions, the Ningxia and Xinjiang strains showed a high degree of similarity. This suggests that the indigenous Chinese strains are distinct from European and new world lineages. Nearly identical strains were only found in the wine samples collected in the same viticulture region with the exception of UCD522 and UCD514 . These results are in agreement with previous studies on geographically close regions and widely distant geographic regions . According to Ezeronye and Legras , who studied the genetics of S. cerevisiae strains isolated from palm wine in eastern Nigeria, geographic and/or ecological isolation results in a specific population of S. cerevisiae. These analyses have led to the conclusion that geographic location plays a significant role in genetic divergence. Strain XJ19 displayed a high similarity with UCD587 , UCD2515 and UCD2516 . The relatedness of these four strains may imply a common origin or a commonality of evolutionary forces in the wild. Interestingly as a group the Chinese wine strains appear to show greater overall diversity as compared to the wine isolates from the rest of the world. This is consistent with the narrowness of the Wine European lineage previously described as well as the observations of overall greater diversity of natural S. cerevisiae isolates from China as compared to other regions . The greater natural diversity of isolates of S. cerevisiae from China many represent an untapped genetic reservoir for strain improvement and breeding programs. Knowledge about indigenous yeast strains can also help preserve and employ the most representative strains from a wine region .When making purchasing decisions about products, consumers traditionally include factors such as price, quality, and availability of substitutes.On the one hand, if a product with safety concerns is removed from the market and the remaining products experience additional safety checks, consumers may perceive the market as being at least as safe as before. On the other hand, if the removal of the unsafe product provides negative information about closely related products or the industry as a whole, consumers may respond by decreasing demand, even in the absence of safety concerns about the remaining products. The empirical question is whether a recall of an unsafe product can have a direct impact on consumer purchases and preferences, even if the remaining products are safe. From a safety perspective, the question is relevant if firm incentives to invest in risk reduction and regulatory compliance in existing regulation depend, to some degree, on consumer responses to recalls.In early July 2010, the Center for Disease Control and Prevention identified a nationwide, four-fold abnormal increase in the number of reported Salmonella infections. A month later, on August 13, 2010, a first egg farm, located in Iowa, conducted a nationwide voluntary recall of around 228 million eggs. By August 18, 2010, the same farm expanded its recall to around 152 million additional eggs. Within 48 hours, on August 20, 2010, a second egg farm, also located in Iowa, conducted another nationwide voluntary recall of around 170 million eggs. In total, from August 13 to August 20, 2010, more than 500 million eggs were recalled, in what would be the largest egg recall in U.S. history .

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The second property that affects the flow rate limitation is the distribution of roots

Our second finding is that economic systems in which wealth is more heritable are indeed more unequal, as predicted by our model. For each population and type of wealth, we estimated the Gini coefficient, which is a measure of inequality ranging from 0 to approximately 1. To calculate an overall measure of wealth inequality for a given economic system we again weight the results for each wealth class in that system by its importance . These estimates of overall wealth inequality appear in the last column of Table 2, and in more detail in table S5. They exhibit the same pattern as the transmission coefficients : hunter gatherer and horticultural populations are both relatively egalitarian; pastoral and agricultural societies are characterized by substantial wealth inequality . A third finding is that neither the overall inter generational transmission of wealth nor the level of inequality is greater in horticultural than in hunter-gatherer populations. This result challenges a long-standing view that foragers are uniquely egalitarian among human societies. Thus, it may be ownership rights in land and livestock, rather than the use of domesticated plants and animals per se, that are key to sustaining high levels of inequality. Our finding that macetas plastico cuadradaspastoralists transmit wealth across generations to an extent equal to if not greater than farmers, and likewise display similar Gini coefficients, will also challenge widely held views that herders are relatively egalitarian . Are the relative inter generational mobility of the hunter-gatherer and horticultural systems and the high levels of inter generational wealth transmission of the pastoral and agricultural systems due primarily to technology or to institutions ? To answer this question,maceta 30 litros we take advantage of the fact that both the importance of the wealth classes and degree of inter generational transmission of wealth are similar in the hunter-gatherer and horticultural populations, on the one hand, and the pastoral and agricultural populations on the other. This allows us to reduce the four systems to two.

Forty-five percent of the large and statistically significant difference between the average a-weighted b values of these two groups of economic systems is accounted for by differences in technology, reflected primarily in the greater importance of material wealth in producing the herders’ and farmers’ livelihoods [for the decomposition formula, see section 1; for the paired economic systems results, see table S3]. The remaining 55% is due to differences in institutions, reflected primarily in the lesser degree of transmission of material wealth in the horticultural and hunter-gatherer populations. Thus, although differences across economic systems in both the importance of the wealth classes and in the heritability of a given class of wealth matter, the latter is somewhat more strongly associated with differences in the extent of wealth transmission across generations, and hence the generation of inequality. This is our fourth finding. Note that for the inter generational transmission of wealth, the effects of technology and institutions are complementary rather than simply additive. Econometric analysis shows that this joint effect of material wealth and agricultural or pastoral economic systems in the inter generational transmission of wealth is statistically robust, even when a fixed-effects regression is used to control for all unobserved population-level characteristics . Not surprisingly in light of our fourth finding, additional econometric analysis [described in section 5 of ] shows that both wealth class and economic system significantly and independently predict the level of wealth inequality: material wealth types, and pastoral and agricultural societies, display higher Gini coefficients . Moreover, the greater inequality in material wealth is robust to the inclusion of fixed effects to control for unobservable population level variation . A final finding is that, in the populations studied, the more important forms of wealth are more highly transmitted across generations: The simple correlation between the 43 b values listed in Table 1 and the corresponding population and wealth-class specific a values listed in table S1 is 0.48 .

This is consistent with the view that parents differentially transmit to their offspring the forms of wealth that are most important in that society . This is most striking in the case of material wealth. In pastoral and agricultural societies, its average importance is 0.60 and the average transmission coefficient is 0.61; in hunter-gatherer and horticultural populations, the values, respectively, are 0.18 and 0.13 . Similarly, the less important forms of wealth in agricultural and pastoral systems display significantly lower b values. We implemented two robustness checks to make sure, first, that our results are not driven merely by the qualitative estimates of a provided by the ethnographers and, second, that these estimates are themselves plausible. The first is the above decomposition of the effects of economic system and wealth class, which shows that a substantial difference between economic systems in aggregate wealth transmission across generations would exist even under the unrealistic assumption that the importance of the wealth classes does not differ across economic systems. The second check is provided by our econometric estimates of the importance of material wealth mentioned above. Note that differences between the estimates of the importance of the two non-material types of wealth are modest, and that e + m + r = 1, so we may group embodied and relational wealth, whose importance we measure by 1 – m*, where m* is the average of our econometrically estimated coefficients for material wealth in pastoral , agricultural , and horticultural production. Using these weights, rather than those estimated by the ethnographers, gives results similar to Table 2 [ section 5], but with even greater differences in the inter generational transmission of wealth between the agricultural and pastoral economies, on the one hand, and the hunter-gatherer and horticultural economies, on the other.Our principal conclusion is that there exist substantial differences among economic systems in the inter generational transmission of wealth and that these arise because material wealth is more important in agricultural and pastoral societies and because, in these systems, material wealth is substantially more heritable than embodied and relational wealth.

By way of comparison, the degree of inter generational transmission of wealth in hunter-gatherer and horticultural populations is comparable to the inter generational transmission of earnings in the Nordic social democratic countries —the average b for earnings in Denmark, Sweden, and Norway is 0.18— whereas the agricultural and pastoral societies in our data set are comparable to economies in which inequalities are inherited most strongly across generations, the United States and Italy, where the average b for earnings is 0.43. Concerning wealth inequality, the Gini measure in the hunter-gatherer and horticultural populations is almost exactly the average of the Gini measure of disposable income for Denmark, Norway, and Finland ; the pastoral and agricultural populations are substantially more unequal than the most unequal of the high-income nations, the United States, whose Gini coefficient is 0.37 . Our model explains some seeming anomalies, such as substantial wealth differences in those hunter-gatherer populations whose rich fishing sites can be defended by families or other corporate groups and transmitted across generations and which constitute an atypically important form of material wealth for those societies . Our findings also provide evidence for the view— widely held among historians, archaeologists, and other social scientists—that some influences on inequality are not captured simply by differences in technology, as measured by our a values. For example, the marked hierarchies among some Australian foragers may be due to polygyny , elite possession of ritual knowledge that may be transmitted inter generationally, or even to the dynamics of food sharing . Similarly,macetas cuadradas plastico the fact that some agricultural and pastoral societies do not exhibit substantial levels of economic inequality despite their characteristic forms of wealth being in principle heritable suggests the importance of deliberate egalitarianism, as well as other cultural influences and political choices . Examples include the lavish funeral feasting that redistributes the wealth of the elite among the Tandroy and other cattle pastoralists in Madagascar and elsewhere . Other examples are the Nordic social democratic polities mentioned above. One may speculate on the basis of these results that the current trend toward a knowledge based economy that is less reliant on material wealth and more reliant on embodied and relational wealth might in the long run be associated with a concomitant reduction in inter generational wealth transmission. But the importance in our data set of economic systems per se as a determinant of the dynamics of inequality suggests that the implications for inequality of this shift in how humans make a living will depend critically on our institutions.Walnut is a tree species of great economic importance, particularly in the Central Valley of California , which provides 99% of the US commercial supply and 66% of the worldwide production of walnut kernels . In California, the majority of walnut orchards are located in areas that are periodically affected by drought. In recent years, drought stress has led to increased tree mortality and a decline in walnut productivity across the state . Identifying how plant traits control the supply of water from the soil to the canopy is of high relevance in order to optimize water application while maintaining orchard productivity under increasing climatic variability. Walnut trees have high water requirements. Their growth is strongly affected by water deficit, which results in decreased yield, deep bark canker, and low kernel size and quality, among other issues . In contrast, early seasonal over-irrigation can cause Phytophthora root rot and dieback . In addition, both nitrate  deficit and climate seasonality can alter root-to-shoot growth allocation jeopardizing the sustainability of tree growing operations . As in other parts of the world currently experiencing changes in climate, the increasingly frequent drought events in California call for adjusted water management, which requires understanding of the relationship between water application and tree transpiration to avoid the undesirable effects of limited and excessive irrigation.

The soil water that is available for plants is held by soil matric forces between field capacity and the permanent plant wilting point . This notion has been revised due to the fact that only a fraction of the total available water in the root zone is “readily” available , while another fraction of soil water is available at longer-term. In other words, from a hydrological perspective, plant water availability is “rate limited” by hydraulic impedances on the pathways of water . Three main properties are thought to control the flow rate-limitation. The first one is the soil hydraulic conductivity, which strongly depends on soil water content, texture and structure . The hydraulic conductivity of a drying soil decreases by orders of magnitude, relative to a saturated soil, limiting the water movement from the bulk soil to the soil-root interface .The number of roots in each soil layer defines the length of the pathway , with shorter pathways resulting in higher plant water availability. The third property defining the readily available water is the plant hydraulic conductance . The maximal water flow rate that can be sent to the shoot to supply transpiration is limited by plant hydraulic conductance, which is mainly controlled by root radial conductivity and total root length , though cavitation may limit the axial transfer of water under drought . While root growth affects plant water availability as mentioned above, soil water content can, in turn, affect root growth in many ways. A first feedback is the closure of stomata in conditions of low soil water availability, which limits photosynthesis and thus decreases the amount of carbon available to be invested in root biomass . In tress, the higher root-to-shoot ratios and rooting depth, and the decrease of the biomass of fine roots and root length under water  deficit it’s well documented in field and laboratory experiments . Accordingly, the growth response is strongly influenced by the severity of the stress . Even a considerable amount of the available energy is invested to the growth of new roots, these young roots take up water more efficiently representing a suitable plant strategy under water  deficit . However, other root traits, such as root density, specific root length and root area are only slightly affected . Also, both high and low soil water contents limit root growth; the former through hypoxia and the latter through soil mechanical impedance . Finally, soil water potential and soil temperature appear to be major factors influencing root growth . Otherwise, at canopy level, many plant physiological processes may be related to the control of water status, and the shifting in isotope composition of plant compounds have been related as an interesting plant signaling of water stress, and described as a different approach for measurement of drought impact on the terrestrial ecosystems .

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Producers of containerized plants face several challenges related to water use and runoff

The phase-out of methyl bromide has proven to be a daunting task for the California strawberry industry. Not only are strawberry producers faced with the likelihood that methyl bromide will no longer be available to them by 2015, but they also must deal with increasing regulatory stringency on the use of all soil fumigants. While fumigants face an uncertain future in California, barrier films can help trap fumigants in the soil and reduce the likelihood of environmental or health impacts associated with fumigants in the atmosphere. It appears very likely in the near future that barrier films will be the only type of film approved for use with fumigants in California.Potential methods of strawberry production that do not use fumigants include growing plants in substrates and using steam treatments or anaerobic soil disinfestation. All of these systems are being evaluated on a much larger scale, from 1 to 10 acres, with different soil types, to determine commercial feasibility and cost effectiveness. It is not likely, nor is it desirable from a pest management perspective, that one nonfumigant system will dominate on a large percentage of the strawberry acreage. Multiple production systems, using fumigants and nonfumigants, would allow producers to rotate treatments to suppress soil pests.Increasing global temperatures coupled States . Long with unpredictable changes in climate term drought in California and other regions threaten food security globally . California has experienced United States has caused growers to abandon extreme drought conditions for several years,macetas de plástico fruit crops and seek alternatives with less causing fruit growers to face water limita- water demand in the short term. Options fortions affecting production and leading to mitigating long term drought in California hundreds of millions of dollars in crop rev- have included crop abandonment, stress irenue losses in 2016 alone .

To lessen the impacts of climate new plantings change and increasing temperatures on food and utilization of lower quality secondary security, it is important to utilize diversified water sources. cropping systems to reduce vulnerability to It has been proposed that physiologists and extreme climatic events as experienced in breeders focus on increasing the efficiency California and other regions of the United of water use in agriculture . Improving production efficiency and drought tolerance through cultivar or variety selection has been proposed in tree crops, such as citrus Prunus species , dates , and coffee . Because tree crops can have a considerable amount of variability in terms of physiological traits, it is useful to study diversity in crop species to determine if there are cultivars that use water more efficiently or are able to be productive in stressful conditions. Because pomegranate is a drought tolerant crop, especially once established , it is a candidate crop for growers wishing to switch from more water intensive species, such as avocado, citrus or almond. Pomegranate is a drought tolerant crop that has been grown in California since the Spanish missionaries arrived from Spain and planted mongrel seeds at missions up and down the coast . The pomegranate variety collection located at the United States Department of Agriculture – Agricultural Research Service National Clonal Germplasm Repository, Davis, CA conserves about 200 genotypes of pomegranate sourced from all over the world, many of which have unique phenotypic traits . Experiments have demonstrated differences in morphology and vegetative growth traits, including differences in relative chlorophyll content, plant vigor, and branching habit, which can be observed during propagation and in the field . Although available literature on pomegranate physiology is scarce, research has shown that there can be differences among cultivars for many physiological traits of pomegranate in other collections, including transpiration rate, stomatal conductance, water use efficiency, photosynthetic rate and chlorophyll content . The objectives of this study were 1) to evaluate four unique pomegranate cultivars for physiological field performance in a semi-arid agroecosystem during morning and afternoon hours; and 2) to determine if there are differences among cultivars for physiological traits that would be conducive to commercial crop production in drought conditions.‘Wonderful’ is the industry standard in many countries and was chosen as a control in the experimental cultivar field trial.

The other cultivars were selected for their unique phenotypes. ‘Eversweet’ is a dwarf-like cultivar bred for coastal climates, with pink fruit peel and aril color, and soft seeds. ‘Haku Botan’ is an ornamental Japanese cultivar that has an upright growth habit with double white flowers and darker green foliage than most other pomegranate cultivars and lacks visible anthocyanin pigments in stem, leaves and fruit. The fruit is very acidic and very light yellow in color. ‘Parfianka’ is an internationally-renowned cultivar that has a bright red peel and arils with soft seeds and a balanced sweet-tart flavor. The tree is extremely thorny and has a bushy, highly branched growth habit with smaller leaves than other pomegranate cultivars. ‘Wonderful’ is commercially widely-grown, and in the USA it accounts for approximately 90- 95% of production. It is a highly vigorous, thorny tree that has high yield with red fruit and red seeds with moderate seed hardness and a sweet-tart flavor. The growth habit is willowy, with a tendency to sucker at the base of the tree. Photosynthesis measurements. During fruit development , an infrared gas analyzer was used to measure maximum rates of net CO2 assimilation , stomatal conductance , and transpiration during the morning and afternoon . Morning photosynthetically active radiation ranged from 1500-1600 µmol m-2·s-1 photosynthetic photon flux density , while afternoon PAR was 1990 µmol m-2·s-1 PFD. Morning measurements were pooled for the four cultivars, which occurred on 22, 23 Aug. 2015 and 26 June 2016. Afternoon measurements were taken on 30 June 2016, which was representative of a typical summer afternoon in Riverside . Gas exchange characteristics were measured on two leaves per tree and a minimum of three trees per cultivar. All leaves were collected for leaf area, which was quantified on a leaf area meter to normalize photosynthesis data . Only the most recently fully-formed, sunexposed leaves were selected for this study. Cuvette temperatures were allowed to vary with field conditions. Leaves were measured in a chamber that provided 1500 µmol m-2·s-1 . Instantaneous water-use efficiency was calculated as A·E-1 and intrinsic water use efficiency was calculated as A·gs -1. Stem water potential measurements. Predawn and midday stem water potential measurements were recorded for each data tree. For predawn water potential, non-actively growing shoots were covered with a plastic bag for 10 min before being pruned, placed in a sealed plastic bag and kept in a cooler bag until transferred to an indoor environment for plant moisture stress measurements with a pressure chamber .

For afternoon stem water potential measurements, canopy-shaded nonactively growing shoots were covered with a plastic bag for 10 min before being pruned, placed in a sealed plastic bag and kept in a cooler until immediately transferred to a cool lit, indoor environment. Stem water potential was immediately measured after being removed from the cooler bag. One stem was measured from three individual trees per cultivar, for a total of three trees, for predawn and midday stem water potential. Statistical analysis. All variables were analyzed with Analysis of Variance . When ANOVA indicated significant differences, post-hoc comparisons were performed utilizing Tukey’s honestly significant difference with an experiment-wise type 1 error rate of α = 0.05. Relationships between all variables were analyzed using linear regression , with relationships among parameters determined using general regression with Minitab Software, version 16 . Block was coded as a random effect and interaction terms were included in the models. For the purposes of this work, the R2 value is the proportion of variation in one variable that is explained by the variation in the regressor variable. Regression models were fit to determine differences in slope coefficients and constants among variables. The focus of this review is on water use and water recycling in container-grown production of greenhouse and nursery specialty crops. The majority of information and insights in this review also have applicability to containerized edible crops grown in open air or under protected culture. In container-grown crop production, water application frequency varies from multiple times per day to once every few days depending on the production system, crop producer, growing season, and environmental conditions, such as rainfall. Use of containers has grown in popularity with nursery growers over the past 50 years because crops can be produced more rapidly and economically and the root zone is easier to modify when compared with field production . Ruter showed that total biomass increased by 27% by growing Betula nigra under pot-in-pot conditions compared with above ground container production,cultivo del frambueso which was likely due to more favorable root zone conditions. Container-grown plants also weigh less and therefore are easier to move and ship, allowing more flexibility at an operation and improving shipping efficiency. Containerization allows growers to sell plants throughout the year regardless of soil conditions or plant growth stage, which increases productivity per unit area. Field operations typically apply lower rates of fertilizer and water on a per meter or per hectare basis compared with container production because soil matrices are typically more chemically and water buffered . Field production also has wider plant spacing compared to both container production in nurseries and greenhouses . As inventories are sold, containerized plants can be consolidated to make room for additional plants, while field operations cannot be consolidated. This greater density of ornamental container-grown crop production results in both higher revenue and increased material and input costs compared with field production. Irrigation must be applied more frequently in containerized production systems compared to field soils, because plant available water is lower within containers filled with soilless substrates, which have high porosity and restricted root volumes . Any water, or agrichemicals applied in excess of the capacity of the container, are unable to be utilized by the plant, or fall outside of the container will likely leach and run off and may eventually impact surface water and groundwater .

Concerns persist that as runoff leaves an operation, sediment and agrichemical contaminants will also be exported . Some growers capture and reuse all or a portion of production runoff, whereas other growers allow runoff to drain from their operations to the surrounding ecosystem. Grower hesitation to capture and reuse runoff can usually be attributed to a reluctance to change practices because of concerns about the opportunity cost of lost production area, installation costs of containment and treatment systems, management costs for treatment technology, reintroduction of disease-causing organisms or plant growth regulators, phytotoxicity of reintroduced pesticides, or land characteristic restrictions . In this review, we will discuss these challenges, as well as potential solutions to these issues and limitations Greenhouses are typically characterized as covered or enclosed systems with the capacity to control environmental factors that impact plant growth, including temperature, humidity, irrigation, and light. Operation sizes typically range from a few hundred square meters to 5 ha but can exceed 10 ha. Greenhouse operations tend to be highly intensive production systems on a per unit area basis, but due to smaller container sizes are typically smaller than container-nursery operations. They typically use precise irrigation applications and can have a high degree of environmental monitoring and control. Thus, greenhouse operations typically require less water per unit area than open-air container or pot-in-pot nurseries . This higher degree of control capability can lead to higher distribution uniformity and water use efficiencies. However, efficiencies also depend on irrigation application method , application decisions , and system design and maintenance. The typical higher efficiency irrigation used in greenhouse operations requires higher-quality water and regular maintenance to avoid emitter clogging and subsequent plant loss or damage. Nursery container operations place containers at or below ground level . Plants are grown on various combinations of bare ground, gravel, landscape fabric, or other surfaces that are often graded to reduce standing water directly below containers. Nursery container operation sizes can vary from less than a hectare to thousands of hectares. Irrigation is typically applied overhead using impact sprinkler heads or similar-type heads. Larger containers are often irrigated using micro-irrigation via drip emitters or spray stakes. Although micro-irrigation is more labor intensive to maintain, the necessity of wider plant spacing due to canopy size makes overhead irrigation inefficient due to wind drift and decreased interception efficiency .

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The C-6 Quad system had an impressive performance throughout the trial

Data from this trial had a similar trend for the relationship between light interception and yield. In the June Flame cultivar, yield measurements up to 50% light interception had little deviation from the linear model, above this point yield varied significantly. Above 50% light interception, differences in yield are likely caused by other limiting factors such as water or nutrients . This would also explain the poor fit for the model of the C-6 V system. With a canopy that intercepted >50% in all three seasons, yield variation was likely a result of environmental conditions. August Flame systems had more time in the first growing season to fill out their allotted space. This resulted in most systems having >50% light interception in all three seasons. Due to the higher light interception, all models had a poor fit and did not provide confident yield predictions.There were often significantly higher fruit counts and larger fruit compared to the Nema Quad system. In the June Flame 2019 harvest data there was a significant difference detected in slopes comparing fruit size vs fruit per hectare however the difference was related to the C-6 Quad system having the best fit to the model for that season. Overall, this system proved capable of producing yields on par with the current commercial systems. The C-6 V system also proved to be a successful alternative to the current standard systems. Fruit sizes and crop loads matched the Nema Quad system in most seasons. High-density plantings may be more suitable for late-bearing cultivars and growers attempting to reach harvest a season earlier may find it difficult to do so with high-density plantings and an early-bearing cultivar. One drawback is the number of trees that must be managed in this kind of a system. With almost 1800 trees per hectare,macetas de plastico initial costs are higher than a planting with half as many or fewer trees. The C-9 Quad system performed poorly compared to all other systems.

These results would suggest that the system is not capable of matching commercial production. However, systems using the C-9 root stock and higher density plantings have been reported to be more productive than data from this trial suggest. With contrasting results from previous studies, nothing conclusive can be proposed. The Nema Quad system did well as a representation of current commercial standards. The strong benchmark provided by this system highlights the impressive productivity of the C-6 V and C-6 Quad systems. Fossil evidence indicates Olive trees originated 20-40 million years ago in the Oligocene, in what is now the eastern Mediterranean Basin . The olive plant was first cultivated ~ 7000 years ago in the Mediterranean basin . Olives are not native to the Americas. Spanish colonists introduced olive cultivation in present day Peru, Chile, and Argentina in 1500s . The Spanish missionaries brought the olives to California in 1700s . Around 1870, several small orchards with many different European varieties were cultivated for oil along the California coast, from San Diego to Sonoma, and in some foothill areas of the Sierra Nevada Mountains. By 1885, there were 2,000 acres of oil olives planted in California. However, this olive oil industry was not competitive against seed oils or European olive oil imports. The “California Style Black Ripe” olive was developed in the early 1900s, and the California industry focused on table olives, increasing to 35,000 acres by the 1980s . However, in the last four decades, the California table olive industry has declined. Stagnant grower prices, high hand-harvest costs and strong international competition with lower-priced imports have decreased the California table olive industry to 15,500 acres in 2020 . During the same period, the olive oil industry increased to 20,000 acres . This rapid reestablishment of a California olive oil industry was greatly facilitated by cultivars bred to remain small, grow in intensive hedgerow orchards, crop early, and be mechanically pruned and harvested . For the past two decades, olive oil has been promoted as a healthier alternative to other fats and oils.

American olive oil sales have increased 100% from 1991 to 2003 and continue to grow. The US ranks as fourth in world olive oil consumption . This increase in olive oil consumption drove the California olive oil industry to increase domestic production, from 247,500 gallons in 1999-2000 to nearly 400,000 gallons in 2004-2005. Currently, most oil olive orchards are in San Joaquin and Sacramento valleys . Average yields for the past decade have ranged from one to six tons per acre of fresh fruit . However, while consumption is increasing and markets are strong, producers struggle to produce the 5 tons per acre and 190 to 210 gallons of oil per acre needed for economic sustainability. The genus Olea in the family Oleaceae has about 35 species, but Olea Europaea L. is the only one that produces edible fruits. Cultivated olives are medium-size evergreen trees that reach ~ four to eight meters tall. They have dense foliage and bear fruits on the previous year’s apical shoot growth. The simple, lanceolate leaves live for two to three years. The petioles are short, with each node composed of two opposite leaves. The fruit is borne on clusters in the axils of the opposing leaves . Olives grow best in Mediterranean climates with mild winters and warm, dry summers. They are cultivated primarily within the 30° to 45° north and south latitudes. Olives are cold sensitive. When actively growing, temperatures below 0°C damage shoots and kill buds. Temperatures slightly above 0°C decrease bloom. An annual mean absolute minimum temperature below -7°C demarcates the geographical range for olive production . Most cultivars require winter chill of ~ 400 hours below 7°C to break dormancy and bloom. Olives are most sensitive to low and high temperatures during bloom. Flowering can be delayed at low temperatures , and high temperatures can limit pollination and pollen tube growth . The optimal temperature for olive pollen germination and pollen tube growth is 20 to 25°C . Sufficient heat accumulation during the growing season is needed for successful fruit maturation. Full fruit development in olives required 1,225 Celsius degree days . When mature, olives are strongly apically dominant with axillary inflorescences borne on the previous year’s shoot growth. Inflorescences form during the previous season on the growing-shoot leaf axils .

The buds are induced in early summer, initiated in the late fall, and differentiate after dormancy into perfect or imperfect flowers. . Their reproductive or vegetative fate will be determined from mid-June to late October. The process of flower bud formation is called floral induction. The presence of fruit on one-year-old shoots inhabits floral induction on the current year’s shoot growth. Thinning an olive tree within six to seven weeks of flowering increases flowering during the following year . The destruction of seeds of very young fruit without destroying the pericarp flowers can also increase the subsequent year’s flowering . Gibberellins, synthesized in the seeds of a developing fruit, were an important inhibitor of floral induction . Olive inflorescences are 1.5 to 4.0 cm long, with 10 to 35 flowers . The inflorescences have a paniculate structure: flowers grow on the central axis and sometimes sub-branching or secondary bearing-axes can occur . Olive flowers are actinomorphic , and the corollas are composed of four white or yellowish white petals .Olive has an andromonoecious reproductive system,macetas rectangulares producing perfect and male flowers on an individual tree . The imperfect male flower has two stamens, with relatively big, bright yellow anthers and short filaments . In perfect olive flowers, the female reproductive system is a pistil with bi-lobed stigma, a short white style, and a green round ovary . The ovary has two locules or cavities, and within each are two ovules. Fruit development requires fertilization of one of the four ovules . The factors that affect the proportion of perfect flowers include substrate competition, cultivar, and environmental conditions . In a normal year. About 50% of flowers are pistillate .Pollination and fertilization are required for fruit production. During pollination, a pollen grain lands on the stigma and germinates, producing a pollen tube, which grows through the stigmatic surface and down the style to the ovary . Ovules of olives are anatropous and during development, they orient so that the micropyle faces upwards . Like many other angiosperms, after successful pollination, one of the two olive male gametes fuses with the egg cell to become the diploid embryo. The other male gamete unites with two polar nuclei to become the triploid endosperm . Only one of the four ovules isfertilized and develops into a fruit. Vascular bundles separate the future endocarp and mesocarp . Botanically, an olive fruit is a drupe. The mesocarp is the fleshy part of the olive and the endocarp is the stony shell that encloses the fertilized embryo. Some argue olives are allogamous, meaning they require, or produce better, with crosspollination. However, they may self-pollinate but often display self-incompatibility, particularly if temperatures are high during bloom . Olive self-incompatibility is attributed to the slow growth of the pollen tubes of the same cultivar through the stigma, resulting in arrival after the ovule has degenerated . However, no failures in fruit set were detected in cross-pollinated Spanish olive groves, so the delay in self-pollinating cultivars might not be the reason for fruit set failure . Mass abscission of young fruit and unfertilized ovaries are a result of competition for assimilates. In the ‘Gordal Sevillana’, cross pollination reduces the number of shot berries and parthenocarpic fruit with little commercial value.

In the ‘Manzanilla de Sevilla’, cross-pollination increases fruit set. However, in other varieties such as the ‘Arbequina’, there is very little difference in the fruit set in response to cross-pollination . A mature olive tree produces abundant flowers, but only a small portion of them persist as fruits . Anthesis of olives lasted seven weeks, starting at bud break . Most inflorescence axis elongation happens during the third week after BB, massive bract shedding occurs the fourth week after BB, and full bloom occurs seven weeks after BB. Intense abscission of flowers and fruits happens five to seven weeks after FB . During the intense abscission period, imperfect flowers abscise before the perfect flowers and fruits, with overlap . Olive yield depends on the population of viable pistillate flowers, their pollination, fertilization, and persistence as fruits . The number of inflorescences affects final fruit set and the number of fruits within one inflorescence is consistent between years and within cultivars . The final olive fruit set correlates positively with the quantity of pollen during bloom . Ovule longevity is fundamental to flower pollination and fertilization in apples, leading the concept of an Effective Pollination Period . EPP is determined by the longevity of the ovules minus the time required for a pollen tube to grow to the ovule. Longer ovule persistence or viability could increase the EPP and, therefore, potentially fruit set in olives .Olive, like apple, pear, mango, and other fruit trees, are alternate bearing, meaning they produce alternating large and small crops . Alternate bearing does not cause harm to trees , but it destabilizes management, production, and marketing . One hypothesis is that carbohydrate depletion during an “on” year due to fruit growth causes low fruit set in the subsequent “off” year . Olive trees placed in growth chambers under favorable conditions for growth: light, temperature, and high CO2 concentration, had five times more non-structural carbohydrate accumulation than controls . However, the olive trees in the chamber still failed to bloom or set fruit successfully. This observation suggested that the lack of photosynthates was not the primary reason for alternative bearing. The developing fruit is an inhibiting factor for floral induction in olive. Reducing the crop load six to seven weeks after flowering resulted in increased flowering for the following year . Olive fruit seed development is a strong influence on inflorescence development . When olive fruit seeds were killed within six weeks after full bloom, leaving the bearing shoots with seedless fruits, the current year’s shoot growth produced more inflorescences the following year than branches with seeded fruits. Gibberellins, synthesized in seeds of developing fruits, were an important inhibitor of floral induction .

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TGB3 also appeared to function in redistribution of membrane vesicles throughout the cytosol

TGB1 and TGB2 also localized with membrane vesicles even though extensive membrane proliferation was not observed. However, ectopically expressed TGB3 elicited formation of a complex and well-defined ER network that is closely associated with, or houses, thick actin cables and TGB proteins.Virus movement and membrane reorganization, which is especially obvious in the perinuclear region, was disrupted by mutations in the central membranespanning domain of TGB3. Our findings thus suggest that host membrane associations are involved in several aspects of BSMV movement that merit future study. In addition to differences in requirements of the coat protein for cell-to-cell movement of hordeiviruses and potexviruses, a number of variations are evident in TGB1 protein structure, biochemical activities, interference with host gene silencing, and movement functions of the virgaviruses and the TGB-containing flexiviruses . A recent paper illuminating a TGB1 requirement for formation of X bodies associated with PVX highlights another major difference in functions of the TGB1 proteins of the hordeiviruses and the potexviruses that relates to BSMV actin remodeling. In contrast to BSMV, in which TGB3 expression has a major effect on actin architecture, PVX TGB1 is essential for X-body formation and functions in extensive actin and membrane remodeling . The multilayered membranous X-body is an important organelle that is required for normal levels of viral RNA replication and virion accumulation. Nevertheless, in plants and protoplasts infected with PVX mutants unable to express TGB1, morphogenesis of X bodies fails to occur, yet low levels of PVX replication can be detected and small amounts of virus particles accumulate . However, ectopic expression of PVX TGB1 results in massive remodeling of host actin and endomembranes, greenhouse ABS snap clamp and recruitment of these structures, as well as TGB2 and TGB3, to sites near the nucleus. Subsequently, X-bodies develop into complex multilayered membrane organelles adjacent to the nucleus, that selectively incorporate TGB proteins, ribosomes, viral RNA and virions to specific sites within the granular vesicular bodies .

These differences between the two viruses are further illustrated by conventional electron microscopic observations showing that structures corresponding to PVX X-bodies are not present in BSMV-infected cells, and that BSMV replicates in membrane vesicles formed from the chloroplast outer membrane . Our current results add to a growing list of major differences in the movement processes of TGB-encoding viruses . We previously reported that cytochalasin D treatment failed to affect TGB1 localization in BSMV infected protoplasts and as a result, postulated that cytoskeletal interactions of the protein were relatively minor. However, the experiments presented here reveal both actin remodeling and changes to ER structure as a consequence of BSMV infection and transient expression of TGB3 and TGB2/3. Our observations also provide evidence that the subcellular localization of the TGB proteins depends on actin cytoskeleton interactions. To investigate these interactions in more detail, we used LatB to inhibit actin polymerization in cells infiltrated with TGBreporter proteins. In contrast to cytochalasin D used in our earlier experiments , LatB can be up to 100-fold more potent than cytochalasins, and functions by shortening and thickening of actin filaments. After LatB treatment, the DsRed:Talin patterns in N. benthamiana infiltrated epidermal leaf cells exhibited a major shift from a filamentous actin network to thick cablelike structures.From these experiments, we conclude that actin cytoskeleton modifications are required for BSMV movement and that TGB3 has a critical role in cytoskeleton remodeling during movement. In contrast to the BSMV LatB experiments described above, experiments with the closely related PSLV TGB3 have resulted in different conclusions about mechanisms functioning in PD targeting . In the case of BSMV, actin cytoskeleton disruption by LatB interfered with CW localization of TGB3, and TGB1 when coexpressed with TGB2/3, whereas PSLV TGB3 CW localization was not dramatically affected by LatB treatment . These disparate results highlight fundamental differences in the mechanisms of subcellular transit of BSMV and PSLV. Such differences between related viruses may occur more often than previously realized, as illustrated by a previous report describing differences in the movement of two tobamoviruses .

In this direct comparison, movement of TMV is strongly inhibited by LatB treatment, whereas movement of the related TVCV is unaffected by LatB treatment. These results argue strongly that more than one mechanism may be operative in some closely related viruses, and our collective results suggest that BSMV and PSLV may fit within this category. Evidence for TGB3 associations with the Golgi membranes during coexpression of DsRed:TGB3 and the STGFP Golgi marker indicates that Golgi derived vesicles and DsRed:TGB3 co-localize with the CW after plasmolysis. BFA interference with Golgi stack integrity resulted in a major collapse of vesicles localized in close proximity to the CW, but BFA appears to have only limited effects on BSMV localization or PSLV TGB3 associations with “peripheral bodies” . Nevertheless, differences in the BSMV and PSLV LatB cytoskeleton disruption experiments suggest that different mechanisms may function in some TGB3 interactions culminating in PD targeting. Other than the preliminary experiments shown above, which suggest that BSMV infection does not result in obvious changes to microtubules, we have not extensively investigated possible direct interactions of BSMV TGB proteins with microtubules. However, in other experiments with the related Potato mop-top virus , colchicine treatments were used to disrupt tubulin polymerization and microtubule integrity . Colchicine can affect multiple metabolic and regulatory processes affecting a large number of functions that might interfere with TGB1 localization to the CW. However, the PD associations of PMTV mutants provided evidence for an association between microtubules and PMTV TGB1. Of particular interest, cells were observed for several days after transient expression of the three TGB proteins in ratios corresponding to those occurring during virus infection. During this period, a defined series of kinetic events were noted, beginning with PMTV TGB1 nucleolar interactions and proceeding through cytoplasmic granules to the CW. Thus, the effects of BSMV and PMTV on microtubule remodeling, seem to differ, and these experiments reinforce our suggestion that multiple pathways may operate in CW targeting during TGB1 expression of the virgaviruses. Unfortunately, individual events involved in viral movement from subcellular sites of replication to the PD and adjacent cells are difficult to dissect experimentally, and many of these problems have been discussed previously .

The infection front where important events are coordinated is a moving boundary consisting of a limited number of cells undergoing a series of asynchronous steps, so relatively few studies have probed events at this stage of infection. Variations in delivery protocols also contribute to experimental differences or artifacts that can lead to aberrant subcellular trafficking effects. In this regard,flower pot wholesale examples of the effects of over expression of PSLV TGB3 has been described recently in which anomalous cell death, membrane abnormalities and disrupted Golgi functions occur during transient infection . Third, pharmacological approaches can be quite variable in the hands of different researchers. Finally, a more diverse array of approaches, including infectivity studies applied to different hosts might provide interesting insights into alternative strategies employed by BSMV and other hordeiviruses. Although it would be preferable to investigate movement in the natural BSMV cereal hosts, these plants present technical difficulties that are difficult to circumvent. Fortunately, BSMV, unlike PSLV, is able to infect N. benthamiana, so we have been able to compare cytological and biochemical experiments with infectivity results in this host.Rust fungi are an order of >7000 species of highly specialized plant pathogens with a disproportionately large impact on agriculture, horticulture, forestry, and foreign ecosystems. The infectious spores are typically dikaryotic, a feature unique to fungi in which two haploid nuclei reside in the same cell. Asian soybean rust caused by the obligate biotrophic fungus Phakopsora pachyrhizi, is a prime example of the damage that can be caused by rust fungi. It is a critical challenge for food security and one of the most damaging plant pathogens of this century. The disease is ubiquitously present in the soybean growing areas of Latin America, where 210 million metric tons of soybean are projected to be produced in 2022/23 , and on average representing a gross production value of U.S. $ 115 billion per season . A low incidence of this devastating disease can already affect yields and, if not managed properly, yield losses are reported of up to 80%. Chemical control in Brazil to manage the disease started in the 2002/03 growing season. In the following season, ~20 million hectares of soybeans were sprayed with fungicides to control this disease. The cost of managing P. pachyrhizi exceeds $2 billion USD per season in Brazil alone. The pathogen is highly adaptive and individually deployed resistance genes have been rapidly overcome when respective cultivars have been released. Similarly, the fungal tolerance to the main classes of site-specific fungicides is increasing, making chemical control less effective. Another remarkable feature for an obligate biotrophic pathogen is its wide host range, encompassing 153 species of legumes within 54 genera to date. Epidemiologically, this is relevant as it allows the pathogen to maintain itself in the absence of soybean on other legume hosts, such as overwintering on the invasive weed Kudzu in the United States. Despite the importance of the pathogen, not much was known about its genetic makeup as the large genome size , coupled to a high repeat content, high levels of heterozygosity and the dikaryotic nature of the infectious urediospores of the fungus have hampered whole genome assembly efforts. In this work, we provide reference quality assemblies and genome annotations of three P. pachyrhizi isolates. We uncover a genome with a total assembly size of up to 1.25 Gb.

Approximately, 93% of the genome consists of TEs, of which two super families make up 80% of the TE content. The three P. pachyrhizi isolates collected from South America represent a single clonal lineage with high levels of heterozygosity. Studying the TEs in detail, we demonstrate that the expansion of TEs within the genome happened over the last 10 My and accelerated over the last 3 My, and did so in several bursts. Although TEs are tightly controlled during sporulation and appressoriaformation, we can see a clear relaxation of repression during the in planta life stages of the pathogen. Due to the nested TEs, it is not possible at present to correlate specific TEs to specific expanded gene families. However, we can see that the P. pachyrhizi genome is expanded in genes related to amino acid metabolism and energy production, which may represent key lifestyle adaptations. Overall, our data unveil that TEs that started their proliferation during the radiation of the Leguminosae play a prominent role in the P. pachyrhizi’s genome and may have a key impact on a variety of processes such as host range adaptation, stress responses and plasticity of the genome. The high-quality genome assembly and transcriptome data presented here are a key resource for the community. It represents a critical step for further in-depth studies of this pathogen to develop new methods of control and to better understand the molecular dialogue between P. pachyrhizi and its agriculturally relevant host, Soybean.The high repeat content and dikaryotic nature of the P. pachryrhizi genome poses challenges to genome assembly methods. Recent improvements in sequencing technology and assembly methods have provided contiguous genome assemblies for several rust fungi. Here, we have expanded the effort and provided reference-levelgenome assemblies of three P. pachyrhizi isolates using long-read sequencing technologies. All three isolates were collected from different regions of South America. We have used PacBio sequencing for the K8108 and MT2006 isolates and Oxford Nanopore for the UFV02 isolate to generate three high-quality genomes . Due to longer read lengths from Oxford nanopore, the UFV02 assembly is more contiguous compared to K8108 and MT2006 and is used as a reference in the current study . The total genome assembly size of up to 1.25 Gb comprising two haplotypes, makes the P. pachyrhizi genome one of the largest fungal genomes sequenced to date . Analysis of the TE content in the P. pachyrhizi genome indicates ~93% of the genome consist of repetitive elements, one of the highest TE contents reported for any organism to date . This high TE content may represent a key strategy to increase genetic variation in P. pachyrhizi. The largest class of TEs are class 1 retrotransposons, that account for 54.0% of the genome.

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Molecular diffusion was neglected as it was considered negligible relative to dispersion

High frequency irrigation systems involve fastidious planning and complex designs, so that timely and accurate additions of water and fertilizer can result in sustainable irrigation. At the same time these production systems are becoming more intensive, in an effort to optimise the return on expensive and scarce resources such as water and nutrients. Advanced fertigation systems combine drip irrigation and fertilizer application to deliver water and nutrients directly to the roots of crops, with the aim of synchronising the applications with crop demands , and maintaining the desired concentration and distribution of ions and water in the soil . Hence a clear understanding of water dynamics in the soil is important for the design, operation, and management of irrigation and fertigation under drip irrigation . However, there is a need to evaluate the performance of these systems, because considerable localised leaching canoccur near the drip lines, even under deficit irrigation conditions . The loss of nutrients, particularly nitrogen, from irrigation systems can be expensive and pose a serious threat to receiving water bodies . Citrus is one of the important horticultural crops being grown under advanced fertigation systems in Australia. Fertigation delivers nutrients in a soluble form with irrigation water directly into the root-zone, thus providing ideal conditions for rapid uptake of water and nutrients. Scholberg et al. demonstrated that more frequent applications of a dilute N solution to citrus seedlings doubled nitrogen uptake efficiency compared with less frequent applications of a more concentrated nutrient solution. Delivery of N through fertigation reduces N losses in the soil-plant system by ammonia volatilisation and nitrate leaching . However, poor irrigation management, i.e., an application of water in excess of crop requirements,hydroponic nft channel plus the storage capacity of the soil within the rooting depth, can contribute to leaching of water and nutrients below the rootzone.

Therefore, optimal irrigation scheduling is important to maximise the uptake efficiencies of water and nutrients . Most of the citrus production along the Murray River corridor is on sandy soils, which are highly vulnerable to rapid leaching of water and nutrients. Nitrogen is the key limiting nutrient and is therefore a main component of fertigation. An increasing use of nitrogenous fertilizers and their subsequent leaching as nitrate from the root zone of cropping systems is recognised as a potential source of groundwater contamination, because the harvested crop seldom takes up more than 25–70% of the total applied fertilizer . Several researchers have reported substantial leaching of applied N under citrus cultivation in field conditions . Similarly, in lysimeter experiments, Boaretto et al. showed 36% recovery of applied nitrogen by orange trees, while Jiang and Xia reported N leaching of 70% of the initial N value, and found denitrification and leaching to be the main processes for the loss of N. These studies suggest that knowledge of the nitrogen balance in cropping systems is essential for designing and managing drip irrigation systems and achieving high efficiency of N fertilizer use, thereby limiting the export of this nutrient as a pollutant to downstream water systems. Quantifying water and nitrogen losses below the root zone is highly challenging due to uncertainties associated with estimating drainage fluxes and solute concentrations in the leachate, even under well-controlled experimental conditions . Moreover, direct field measurements of simultaneous migration of water and nitrogen under drip irrigation is laborious, time-consuming and expensive . Hence simulation models have become valuable research tools for studying the complex and interactive processes of water and solute transport through the soil profile, as well as the effects of management practices on crop yields and on the environment .

In fact, models have proved to be particularly useful for describing and predicting transport processes, simulating conditions which are economically or technically impossible to carry out in field experiments . Several models have been developed to simulate flow and transport processes, nutrient uptake and biological transformations of nutrients in the soil . HYDRUS 2D/3D has been used extensively for evaluating the effects of soil hydraulic properties, soil layering, dripper discharge rates, irrigation frequency and quality, timing of nutrient applications on wetting patterns and solute distribution because it has the capability to analyse water flow and nutrient transport in multiple spatial dimensions . In the absence of experimental data we can use multidimensional models solving water flow and nutrient transport equations to evaluate the multi-dimensional aspect of nitrate movement under fertigation . However, earlier simulation studies have reported contradictory results on nitrate distribution in soils. For example, Cote et al. reported that nitrate application at the beginning of an irrigation cycle reduced the risk of leaching compared to fertigation at the end of the irrigation cycle. On the other hand, Hanson et al. reported that fertigation at the end of an irrigation cycle resulted in a higher nitrogen use efficiency compared to fertigation at the beginning or middle of an irrigation cycle. These studies very well outlined the importance of numerical modelling in the design and management of irrigation and fertigation systems, especially when there is a lack of experimental data on nutrient transport in soils. However, there is still a need to verify the fate of nitrate in soils with horticultural crops and modern irrigation systems. Therefore, a lysimeter was established to observe water movement and drainage under drip irrigated navel orange, and to calibrate the HYDRUS 2D/3D model against collected experimental data. The model was then used, in the absence of experimental data on nitrate, to develop various modelling scenarios to assess the fate of nitrate for different irrigation and fertigation schemes.The study was conducted on a weighing lysimeter assembled and installed at the Loxton Research Centre of the South Australian Research and Development Institute. The lysimeter consisted of a PVC tank located on 1.2 m × 1.2 m pallet scales fifitted with 4 × 1 tonne load-cells, and connected to a computerised logging system which logged readings hourly.

A specially designed drainage system placed at the bottom of the lysimeter consisted of radially running drainage pipes,nft growing system which were connected to a pair of parallel pipes, which facilitated a rapid exit of drainage water from the lysimeter. These pipes were covered in a drainage sock and buried in a 25-cmlayer of coarse washed river sand at the base of the lysimeter, which ensured easy flushing of water through the drainage pipe. A layer of geo-textile material was placed over the top of the sand layer to prevent roots growing down into it, as this layer was intended to be only a drainage layer. A healthy young citrus tree was excavated from an orchard at the Loxton Research Centre and transplanted into the lysimeter. A soil profile approximately 85 cm deep was transferred to the tank with the tree and saturated to remove air pockets and to facilitate settling. The final soil surface was around 10 cm below the rim of the tank. Soil samples were collected from0 to 20, 20 to 40, 40 to 60, 60 to 85, and 85 to 110 cm depths to measure bulk density and to carry out particle size analysis. Two months after transplanting, the lysimeter was installed amongst existing trees in the orchard. Measurements were initiated after about six months, in order to enable the plant to adjust to the lysimeter conditions. The lysimeter was equipped with Sentek® EnviroSCAN® logging capacitance soil water sensors installed adjacent to the drip line at depths of 10, 20, 40, 60, and 80 cm to measure changes in the volumetric soil water content. Drainage water was directed through flexible piping into a large bin installed below ground level. The experimental site was approximately 240 m from an established weather station, which measured air temperature, relative humidity, wind speed , rainfall, and net radiation.Irrigation was applied using 3 pressure compensated emitters with a discharge rate of 4 L h−1. Emitters were located on a circle 25 cm away from the tree trunk at an equal distance from each other . The irrigation schedule was based on the average reference evapotranspiration during the last 10 years at the site, multiplied by the crop coefficient taken from Sluggett . The cumulative crop evapotranspiration during the 29 day experimental period was equal to 65.3 mm, and daily ETC varied from 1.68 to 3.39 mm. Irrigation was initiated on 16 August 2010 and terminated on 13 September, 2010. Irrigation and rainfall were recorded daily and drainage volume was measured 3 times per week throughout the trial period. Daily irrigation was applied in 5 short pulses using an automated irrigation controller, with 2 h breaks between irrigation pulses. The amount of irrigation water applied was slightly higher than ETC for the period. A total of 70 mm of rainfall fell during the experimental period, including a single event of 52 mm on 3 September 2010.The simulation domain was represented by a 110-cm deep and 100-cm wide cylindrical cross section. Drip irrigation was modelled as a circular line source 25 cm from the centre of the lysimeter with a uniform water flux along the drip line.

This simplification was made to enable HYDRUS to model this problem in a 2D axi-symmetrical mode , rather than in a full 3D mode, which would be computationally much more demanding. Additionally, since the surface wetted area and input flux densities under drippers were dynamic, an option that we would not be able to model with HYDRUS in a 3D mode, we assumed that the simplification of the problem to axi-symmetrical 2D was adequate. Moreover, the drainage system laid out in the lysimeter also supported the use of an axi-symmetrical domain as the drainage pipes run in a circular fashion to collect and flush drainage water out of the lysimeter. The transport domain was discretized into 3294 finite elements, with a very fine grid around the dripper and near the outflow , with gradually increasing element spacing farther from these two locations . Simulations were carried out over a period of 29 days.Since most soils on which citrus is grown in South Australia are coarse textured soils with good drainage, high oxygen levels, low organic matter, and low microbial populations, denitrification and mineralisation was assumed to be negligible in this study. Similarly, the soil adsorption of nitrate was also considered to be negligible since both nitrate and solid surfaces are negatively charged. Plant uptake of non-adsorbing nutrients like nitrate is controlled mainly by mass flow of water uptake . Therefore, it was assumed that nitrate was either passively taken up by the tree with root water uptake or moved downward with soil water. Spatial distribution of nitrate in the transport domain was thus simulated using the convection–dispersion equation for a nonreactive tracer. The longitudinal dispersivity was considered to be 5 cm, with the transverse dispersivity being one-tenth of this . Similar values of these parameters have been used in other studies .Citrus trees in this region are fertilised from early September till March, and in drip systems fertilizers are mostly applied with the second irrigation pulse for the day. All fertigation scenarios reported here are hypothetical. Fertigation was assumed to be supplied with the same quantity of water as in irrigations without fertigation and to conform to the 2D axi-symmetrical domain. For the initial scenario, fertigation pulses were applied from 30 August 2010 at the rate of one fertigation pulse each day. These were followed by 2 days without fertigation and then another daily fertigation pulses. The resultant dose of N for the period from August till September was calculated based on recommended fertilizer application practices for 5–6 year old orange tree. The seasonal recommended dose of nitrogen for an orange tree of this age is 139 g N applied from September to March . Hence for the seasonal simulation, nitrogen was assumed to be applied in equal monthly doses , in similar pulses as described for the experimental period. The simulation was run for 300 days in order to evaluate the fate of seasonally applied nitrogen fertilizer in citrus. Further scenarios examining the impact of timing of nitrogen application on the efficiency of nitrogen uptake simulated a fertilizer application either at the beginning , middle , or end of the daily irrigation scheme. Since the daily irrigation consisted of 5 pulses, fertigation was applied during the 2, 3 and 4 irrigation pulse in the PF1, PF2 and PF3 scenarios, respectively. It is a common practice that the initial and final irrigation pulses are fertilizer free to ensure a uniform fertilizer application and flushing of the drip lines. In addition to these simulations, two continuous fertigation scenarios were also performed to compare pulsed and continuous fertigation.

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Nft Hydroponic System Flow Rate

The flow rate of an NFT (Nutrient Film Technique) hydroponic system depends on various factors, including the size of the system, the number of plants, and the specific requirements of the plants being grown. However, I can provide you with a general guideline for the flow rate in an NFT system.

In an NFT system, a thin film of nutrient solution continuously flows over the roots of the plants, providing them with water and nutrients. The flow rate is typically measured in liters per hour (L/h) or gallons per hour (GPH).

A common recommendation for the flow rate in an NFT system is around 1-2 liters per minute per square meter of growing channel. This means that for every square meter of NFT channel, the system should provide a flow rate of 60-120 liters per hour (or approximately 15-30 gallons per hour). This guideline ensures that there is a sufficient supply of water and nutrients to the plants’ roots while also allowing for efficient drainage and oxygenation.

Keep in mind that this is a general guideline, and the flow rate can be adjusted based on the specific needs of your plants, the environmental conditions, and the stage of growth. It’s always a good idea to consult specific resources or seek advice from experienced hydroponic growers to determine the optimal flow rate for your particular setup.

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What Are The Different Ways To Grow Hydroponic Farming

Hydroponic farming offers various methods for growing plants without soil. Here are some of the different ways to practice hydroponic farming:

  1. Nutrient Film Technique (NFT): In this method, a thin film of nutrient-rich water continuously flows over the roots of the plants, allowing them to absorb nutrients while also receiving oxygen. The plants are usually placed in troughs or channels with a slight slope to facilitate the flow of the nutrient solution.
  2. Deep Water Culture (DWC): DWC involves suspending plant roots in a nutrient solution with the support of a floating platform or raft. The roots are submerged in the oxygenated solution, providing constant access to nutrients and oxygen.
  3. Drip System: Drip irrigation systems deliver nutrient-rich water directly to the plant’s root zone through small tubes or emitters. The solution is dripped or sprayed onto the medium or roots, allowing the plants to absorb the nutrients. Excess solution is collected and recirculated.
  4. Aeroponics: Aeroponics is a method where the plants’ roots are suspended in air, and a nutrient mist is sprayed directly onto the roots. This method ensures maximum oxygenation for the roots and efficient nutrient uptake.
  5. Wick System: The wick system is a passive hydroponic method where a wick, such as a cotton rope, transfers the nutrient solution from a reservoir to the plant’s growing medium. The wick draws up the solution, providing moisture and nutrients to the roots.
  6. Ebb and Flow (Flood and Drain): This method involves periodically flooding the growing tray or container with nutrient solution and then allowing it to drain away. The flooding and draining cycles provide oxygen to the roots while ensuring they receive the necessary nutrients.
  7. Vertical Farming: Vertical hydroponic systems utilize vertical space to grow plants in stacked layers or towers. This method maximizes the use of limited space and allows for high-density cultivation.
  8. Nutrient Film Technique (NFT): The NFT system uses a constant flow of nutrient-rich water in a shallow channel, allowing the plant roots to access the solution while being exposed to air. The nutrient film provides continuous nutrient supply and oxygenation.

These are just a few examples of the many hydroponic farming methods available. Each method has its own advantages and considerations, and the choice depends on factors such as plant type, available space, resources, and personal preference.