Tag: vertical farming equipments

Posted on

Nitrate-supplied plants accumulated the greatest amounts of nutrients at ambient CO2

The shoot biomass data suggest that growth differences measured early in the lifespan of wheat supplied with NH4 + or NO− 3 or NH4 + do not necessarily carry through to senescence. This may be due in part to a shift in NO− 3 assimilation to the root , allowing NO− 3 -supplied plants to compensate for the decrease in shoot NO− 3 assimilation that occurs at elevated atmospheric CO2 concentrations . The decrease in yield and biomass measures at elevated CO2 concentrations does not agree with field observations where wheat yields as well as overall biomass increased with elevated CO2 . Similarly, our results that the greatest values for other yield measures occurred at ambient CO2 concentrations varies from the literature. High CO2 has been found to increase flowering tillers , KN , and kernel mass . Conflicting results, however, have also been reported . Many of the field and open top chamber studies were grown under natural light and thus received substantially greater photosynthetic flux density than our chamber-grown plants. These higher light conditions would be more favorable to biomass accumulation. Also, these studies typically applied high amounts of mixed N fertilizer , and yields and biomass have been found to be greater under mixed N nutrition than under either NH4 + or NO− 3 alone . Finally, the wheat cultivar we used is a short-statured variety that has rarely been used in other studies and may have accounted for some of the differences between our study and other published data. Our results that NH4 + -supplied plants had greater yield and yield components than NO− 3 -supplied plants at ambient CO2 have been observed previously . Wang and Below observed greater numbers of kernels head−1 and KN in plants supplied NO− 3 that was not observed here. Their study, however, supplied NH4 + at relatively high levels . Several studies have found that incipient NH4 + toxicity can start appearing at N levels as low as 0.08–0.2 mM NH4 + ,vertical farming equipments although the onset of NH4 + toxicity depends on light level and solution pH . The poorer performance of the NH4 + treatment in Wang and Below , therefore, might derive from NH4 + toxicity.

We have previously determined that the 0.2 mM NH4 + -supplied to our plants to be sufficiently high for normal growth, but low enough to avoid toxicity problems under our experimental conditions . Our second hypothesis, that nutrient concentrations are differentially affected by the inorganic N form supplied to the plants and CO2 enrichment, was supported by our data. CO2 concentration and N form interactions may alter tissue demands for nutrients. For many nutrients, ratios between different elements are typically maintained within a narrow range . CO2 concentration and N form may disturb the balance between different nutrients, leading to a cascade of changes in demand, accumulation, and allocation among the different plant tissues .Some portion of the greater response of NH4 + -supplied plants to CO2 derived from a dilution effect from the greater biomass at ambient CO2 concentrations . Total amounts of nutrients tended to decline with CO2 enrichment for NH4 + -supplied plants, which had the greatest amounts of macro/micro-nutrients at sub-ambient CO2 . These results have not been observed in other published studies . Growth chamber studies, however, tend to have more exaggerated differences among treatments than field and greenhouse experiments , and N source cannot be well-controlled in field and greenhouse experiments. The observed increase in NO− 3 −N concentration with CO2 concentration in NO− 3 -supplied plants has been reported previously , and adds further support to the hypothesis that elevated CO2 concentrations and the resulting decrease in photo respiration inhibit shoot NO− 3 photo assimilation. Nevertheless, tissue NO− 3 − N concentrations observed here were substantially lower than those in the earlier study . Again, this may derive from difference in life stages in the two studies. Most of the N available to the plant for grain filling comes from N translocation rather than uptake from the substrate . Probably, the plants continued to assimilate plant NO− 3 using a non-photo respiratory dependent process such as root assimilation after root N uptake slowed or stopped. Loss of NO− 3 through root efflux to the nutrient solution also may have contributed to the lower concentration of NO− 3 − N.

The partitioning and accumulation of all mineral elements was affected in some manner by the CO2 treatment and N form supplied to the plants. Observations that cation concentrations decrease under NH4 + supply relative to NO− 3 supply were not apparent in this study. Again, this could be partly due to the relatively low concentration of NH4 + -supplied in our study, the age of the plants at harvest, and differences among wheat cultivars. Allocation of nutrients within the plant followed similar trends for both N forms, with the exceptions of Mn and Cu . Interestingly, in NO− 3 -supplied plants, shoot Mn concentrations increased slightly with CO2, and these plants allocated far more Mn to the shoots than NH4 + -supplied plants at all CO2 concentrations. Manganese has been found to activate Rubisco in place of Mg2+ and the Rubisco-Mn complex has been observed to decrease Rubisco carboxylase activity while minimally affecting or even enhancing oxygenase activity . The slight increase in shoot Mn with CO2 corresponded to a large 23% decrease in Mg concentration. Manganese, which can act as a cofactor for glutamine synthetase , was also the only nutrient that NH4 + -supplied plants allocated a greater percentage to the roots at the expense of the shoots. NO− 3 – supplied plants typically allocated a higher percentage of most nutrients to the roots, as has been reported previously . Phytate, which forms complexes with divalent cations, has been found to hinder human Zn and Fe absorption during digestion and thus has been labeled an “anti-nutrient.” It may serve a number of valuable functions, however, including roles as an anti-oxidant and anti-cancer agent . Phytate is also the major repository of grain P, and variation in P supply to the developing seed is the major determinant of net seed phytate accumulation . To our knowledge, no published studies have explicitly looked at how phytate is affected by CO2 concentration. Elevated CO2 has been found to have a much larger negative impact on Zn and Fe concentrations than on P in wheat .

Several studies have observed that P increases slightly with CO2 concentration, and because the majority of P is tied up in phytate, this may cause increases in grain phytate concentrations as atmospheric CO2 rises. As a result, bio-available Zn and Fe–Zn and Fe not bound to phytate – is expected to decrease even further . Nonetheless, we did not observe such trends in macro- and micro-nutrient concentrations in this study. The mechanism behind these contrasting results is not clear, although the environmental conditions and nutrient solution in which the plants were grown likely had some role. The modeled data demonstrated only a small negative impact of CO2 concentration on bio-available Zn concentrations , which was unexpected. Indeed, the grain from NO− 3 -supplied plants actually showed a slight increase in bio-available Zn between ambient and elevated CO2. These results combined with the differences in grain bio-available Zn between NH4 + and NO− 3 -supplied plants demonstrates that N form may differentially affect the nutritional status of this important nutrient, especially in less developed countries that might be more dependent on phytate-rich grains for their Zn nutrition . The milling process removes some, if not most, of the phytate and grain mineral content with the bran fraction of the grain . Regardless, with over 50% of the human population suffering from Zn deficiencies, even small increases in bio-available Zn would be beneficial . This modeling exercise, however, is not a prediction of how increasing CO2 will affect wheat nutrition so much as illustrates that N source may mediate, to some extent, the effects of CO2 on phytate and bio-available Zn, and that N source will become an even more important agricultural consideration in the future. In summary, both CO2 concentration and N form strongly affect biomass and yield in hydroponically grown wheat, as well as nutrient concentrations in above- and below ground tissues. Interactions among plant nutrient concentrations,CO2 concentrations,vertical grow system and N form are complex and non-linear. The impact of N form and CO2 concentration on the mechanisms affecting nutrient accumulation and distribution requires further research and extension to more realistic and agriculturally relevant growing conditions found in greenhouse and field studies. Of course, in greenhouse and field studies, control of N source is limited and control of atmospheric CO2 concentration is expensive. The effects of CO2 and N form on agriculture and human nutrition observed here are interesting and suggest a new area of research on mitigating the effects of climate change on agriculture. The supply of fertilizers or addition of nitrification inhibitors that increase the amount of available NH4 + may have beneficial effects for human nutrition, particularly in regards to micro-nutrient deficiencies such as Zn and Fe that currently affect billions of people worldwide. In the face of the potentially negative consequences of climate change on agriculture, all avenues of mitigation must be examined, and even small improvements may prove worthwhile.Features of the seven-story Paharpur Business Center and Software Technology Incubator Park in New Delhi India have been described. A notable feature of the building is the stated goal of providing a healthy work environment for building occupants with specific interest in maintaining superior indoor air quality.

To achieve this goal, the building utilizes several innovative air cleaning technologies, such as air washing to remove the more polar volatile contaminants, bio-filtration of building makeup air using an enclosed rooftop greenhouse with a high density of potted plants, passive treatment of indoor air using a large number of potted plants distributed throughout the building, dedicated secondary heating, ventilation and air conditioning air handling units on each floor with re-circulating high efficiency filtration and ultraviolet light treatment of heat exchanger coils, and air exhaust via the restrooms located on each floor. The idea of using potted plants to remove VOCs from the indoor environment was originally introduced by Wolverton et.al.. In addition to treating the air, the PBC management recognizes the importance of reducing potential sources of indoor chemicals by providing environmentally friendly cleaning products exclusively for the building and selecting certain materials during renovations including a combination of stone, tile and ‘zero VOC’ floor covering and solid sawn wood materials for trim, paneling and furniture, with minimal use of composite wood products. A recent short-term field study collected indoor air quality measurements at the PBC to investigate the performance of the bio-filtration air cleaning system. The study focused primarily on VOCs and aldehydes and collected measurements at several locations in the building representing the transfer pathway of air moving through the building starting on the roof outdoors and following through the rooftop greenhouse, indoors on two floors, and at the building exhaust locations. The study found that for most contaminants, the levels of common indoor VOCs and aldehydes generally increased as the air moved through the building, indicating the presence of indoor sources. The study concluded that even with the extensive effort given to maintaining superior IAQ, the building still had concentrations of VOCs and carbonyls similar to that found in other office buildings. However, the authors point out that given the outdoor air quality in New Delhi compared to the outdoor air quality where the comparative IAQ studies have been carried out for other office buildings, the findings of the short-term study may indicate some added benefit of the bio-filtration-based air cleaning technology. The increase in concentration for several VOCs and carbonyls as the air moved through the building indicated the presence of an indoor source for these chemicals. The contribution of indoor chemicals from different building materials and building contents have been investigated for a range of building types and typical concentrations measured in these buildings have been summarized. The purpose of this project was to investigate the potential source of VOCs and carbonyls in the PBC.

Posted on

Containers with plants grown in non-spiked nutrient solution were included as blank controls

All plant treatments were created in quadruplicate and solution treatments were created in triplicate. Laboratory blanks were included with each sample extraction and pure methanol was analyzed in each UPLC/MS/MS run to check potential contamination. Surrogates were used in all sample analyses to account for losses during extraction and matrix effects during instrumental analysis. Recovery of the surrogates was used to calculate the actual concentration of each target analyte. Recoveries of surrogates in plant tissue and nutrient solution samples are listed in Table S5.1 of the Supporting Information. Statistical analysis of data including ANOVA with Tukey’s Honestly Significant Difference, linear regression, and t-test was performed using R . Significance was assigned at p ≤ 0.05. Carrot, lettuce, and tomato plants grown in both environments were found to be generally healthy, and no difference in biomass was detected between plants grown in solution with or without PPCP/EDCs. For the same plant species, those from the warm-dry environment generally had greater bio-masses. One tomato plant from the cool-humid treatment had yellow, stunted leaves and was excluded from the analysis. The nutrient solution pH was measured at each solution exchange, and was found to average pH 5.2 for carrot, pH 5.3 for lettuce, and pH 6.0 for tomato during the study. The average pH values were used to calculate the neutral fraction and the pH-adjusted octanol-water partition coefficient for the different PPCP/EDCs, as described in Wu et al. . Only small differences in neutral fractions and log Dow values were seen between treatments for the same compound,vertical vegetable tower mostly for compounds with pKa values near the solution pH. Based on the primary ionic state in the nutrient solution, the selected PPCP/EDCs were placed in either the anionic, cationic, or neutral group .

The transpired mass for each plant was measured at every solution exchange and the data were used to calculate the cumulative transpiration . For lettuce and tomato, the different temperatures and air humidity resulted in significantly different transpired masses . The differences were smaller for carrot seedlings , likely due to the considerably smaller leaf masses of the carrot plants. The mean transpired masses in the cool-humid and warm-dry treatments during the 21 d of growth were, respectively, 65.50 ± 19.36 and 194.33 ± 30.72 g/d for lettuce, 127.04 ± 15.52 and 503.38 ± 59.76 g/d for tomato, and 16.82 ± 8.05 and 55.31 ± 26.41 g/d for carrots. For the same plant type, the warm-dry environment induced a 3-4-fold increase in plant transpiration as compared to the cool-humid environment. The dissipation of PPCP/EDCs from nutrient solution during the hydroponic growth of plants may be attributed to plant uptake and microbial degradation in the solution. The change in PPCP/EDC concentrations was measured on day 10, after 2 d incubation. In the spiked nutrient solutions without plants, most PPCP/EDCs showed limited dissipation from the solution , suggesting that these compounds were mostly stable in the nutrient solution . The only exception was atorvastatin, where 49.0% and 61.7% were not recovered for the cool-humid and warm-dry treatments, respectively . In the presence of plants, levels of PPCP/EDCs in the solution significantly decreased compared to the plant-free control. For example, after exposure to a tomato plant, about 38.8% of the initially spiked diclofenac was not recovered from the solution for the cool humid treatment and about 75.6% for the warm-dry treatment, while there was essentially no chemical loss in the plant-free container . When all compounds were pooled, removal from the solution was found to be consistently greater in the warm-dry treatment than in the cool-humid treatment. This difference was statistically significant for lettuce and tomato , but not for carrot , likely due to its very small biomass. For example, in the cool-humid and warm-dry treatments, the respective losses of gemfibrozil were 18.2% and 28.6% for carrot, 64.5% and 89.2% for lettuce, and 55.6% and 91.8% for tomato .

These trends clearly suggested that the warm-dry environment and the corresponding larger plant biomass in the warm-dry treatments, contributed to enhanced PPCP/EDC dissipation in the nutrient solution . The transpired mass over the 2 d period was compared to the measured removal of the anionic, cationic, or neutral PPCP/EDCs over the same period to assess the effect of plant transpiration on the removal of PPCP/EDCs from the nutrient solution. A significant positive relationship was found for each group of compounds , suggesting that the removal of PPCP/EDCs in the nutrient solution increased with transpiration for both ionic and neutral compounds, and across different plant species. The separation of PPCP/EDCs by ionic state in the regression analysis decreased the model residuals for both the cationic and neutral groups, as compared to a linear regression with all compounds grouped together , showing that consideration of ionic states better describes the interaction of PPCP/EDC and transpiration. Transpiration had the greatest impact on removal of neutral compounds, as shown by a slope of 0.048 for the linear regression , followed by anionic compounds , while removal of cationic compounds was least affected by transpiration . Since neutral compounds are expected to move through root membranes according to diffusion, and ionic compounds are subject to electrical effects, it is reasonable to expect that transpiration exerts the most effect on neutral compounds. Other compound characteristics besides ionic state, such as hydrophobicity and stability, may also influence PPCP/EDC dissipation in the nutrient solution and may help explain the remaining regression residuals. To evaluate the contribution of adsorption to root structures, log Dow values for each group of compounds were compared to their removals in the nutrient solution. However, no significant relationship was found for any of the treatments , suggesting that log Dow alone was not a good predictor for PPCP/EDC removal from the nutrient solution. It must also be noted that due to the small number of compounds in the cationic group, the analysis may not be sufficiently strong to be generalized for other cationic PPCP/EDCs.

To facilitate comparisons of PPCP/EDC accumulation among different compounds and between different treatments, a bio-concentration factor was calculated by dividing the concentration of a compound in a plant tissue after the 21 d cultivation to the concentration in fresh solution . In this study, atorvastatin, diclofenac, and clofibric acid were the least accumulated , while perfluorooctanoic acid, diazepam, and diuron were the most accumulated compounds . After averaging across all compounds and plant types, BCF values for root tissues were found to be significantly higher than those for leaves , with the respective mean BCF values of 51.3 and 21.0. These BCF values suggest that many PPCP/EDCs have the ability to bio-accumulate in plant tissues, and the overall accumulation into roots likely exceeds that into leaves. In addition, some PPCP/EDCs may be accumulated to relatively high levels. In general, BCFleaf values followed the order cationic ≥ neutral > anionic and BCFroot values were in the order anionic > neutral ≥ cationic,vertical farming equipments suggesting that accumulation of cationic and neutral compounds was somewhat similar. However, anionic compounds were accumulated significantly less than cationic or neutral compounds in leaves, but significantly more in the roots. The reversed trends of accumulation between leaf and root tissues were mainly caused by the behavior of anionic compounds. For anionic PPCP/EDCs, accumulation in root was significantly more than in leaf , with the mean BCF root at 72.8 while the mean BCFleaf at 3.3. In comparison, accumulation into leaf and root tissues was similar for cationic or neutral compounds . Overall, these results suggest that root tissues may accumulate high levels of anionic compounds, while in leaf tissues, cationic and neutral compounds may be more prevalent. A few other studies have considered some of these same PPCP/EDCs under hydroponic conditions, but often used higher spiking concentrations. Herkltoz et al. investigated the growth of cabbage in solution spiked with carbamazepine, sulfamethoxazole, and trimethoprim at 232.5 µg/L and found BCF values of 0.045 – 0.081 in leaf tissues and 7.04 – 10.92 in root tissues, values similar to this study for sulfamethoxazole and carbamazepine in root , but lower than carbamazepine accumulation in leaves or trimethoprim accumulation . In another study, Zhang et al. measured the uptake of clofibric acid by Scirpus validus from a culture spiked at 0.5 – 2 mg/L, and observed wetweight BCFs of 9.5 – 32.1 in leaf tissues and 6.6 – 23.2 in root tissues. These values were similar to the uptake of clofibric acid in this study . Wu et al. examined many of the same compounds at similar concentrations in nutrient solution growing cucumber, lettuce, pepper, or spinach under greenhouse conditions and observed similar BCF values in leaf and root tissues. The different environment conditions influenced bio-concentration of the PPCP/EDCs in the test plants. The mean overall BCF in the warm-dry treatment was 33.7, which was greater than that in the cool-humid treatment , although the difference was not statistically significant , likely due to the large differences in plant biomass and the wide range of chemicals used in this study. However, when BCFleaf was correlated to the transpired mass during the 21 d of plant growth, a positive correlation was observed for anionic, cationic, and neutral compounds . This result suggests that the mass flow of water caused by plant transpiration influenced the accumulation of PPCP/EDCs in leaves. Transpiration had the greatest impact on the leaf bio-concentration of cationic PPCP/EDCs, as shown by a model slope of 0.0067, while the effect was less for neutral PPCP/EDCs and much less for anionic PPCP/EDCs, suggesting that increased transpiration will have the greatest effect on leaf uptake of cationic compounds and little effect on leaf uptake of anionic compounds. This result is somewhat different than that seen for the removal of PPCP/EDCs from the nutrient solution. The difference may be attributed to other factors in addition to plant uptake, including microbial degradation in the nutrient solution.

In contrast, a relationship between BCFroot and transpired mass was only observed for the neutral group . High residuals in the linear model analysis further suggested that other factors, such as plant species, metabolism after uptake, and likely other compound properties, may also be important in describing PPCP/EDC accumulation into plant tissues. For anionic compounds, it is known that the negative charged molecules may experience repulsion from negatively charged root cell membranes, and that plant accumulation of anions may be mainly due to diffusion of the neutral fraction through the membrane and ion trap effects . A comparison of BCF values of anionic compounds in all plants with their respective log Dow showed a negative correlation for BCF leaf or BCF root , suggesting that anionic compounds with lower effective hydrophobicity had higher accumulation in the leaf or root tissues . This effect was greatest for root tissues, and the slope of the linearized regression was -54, while for leaf tissues the slope was only -0.63, suggesting other factors besides hydrophobicity may have a larger impact on the aerial uptake of anionic compounds. The cationic fraction of a compound may slowly diffuse through plant membranes due to electrical attraction between the positively charged molecules and the negatively charged cell membrane, while the neutral fraction may diffuse with preference to compounds of moderate hydrophobicity . In this study, a positive correlation was observed between BCF leaf and log Dow for cationic PPCP/EDCs in all plants , suggesting that more hydrophobic cationic PPCP/EDCs have a higher accumulation potential in leaf tissues. Further, this effect was relatively strong, with a slope of 10 for the linear regression, as compared to a slope of 6.6 for neutral compounds or -0.63 for anionic compounds. It has been shown that the accumulation of cationic organic compounds in aerial tissues was the greatest for compounds with log Kow between 2.5 –5.5 . In this study, for example, uptake of dilantin into the leaves was greater than that of trimethoprim . In comparison, no significant correlation was observed between BCFroot and log Dow for cationic compounds , suggesting that other factors also contributed to the accumulation of cationic compounds in roots. However, it must be stated again that the limited pool of cationic compounds in this study hampered a more conclusive examination of cationic PPCP/EDCs and that the assumption merits further validation.