Deficiency of B has been identified as a serious agricultural issue in more than 100 crops in 80 countries . Limitation of B impairs growth of young tissues and seed set, which results in depressed quality and quantity of agricultural products. In rice, B content is up to 10-time lower than those of dicot plants . And thus rice young seedling is relatively resistant to B limited condition compared to dicot plants such as Arabidopsis . However, the effect of B limitation until the reproductive phase is little known in rice. In this study, we evaluate the growth and yield of rice subjected to B deficient condition by hydroponic experiments. We previously reported that a boron efflux transporter OsBOR1 plays a crucial role in efficient root-to-shoot translocation in rice . Over-expression of AtBOR1 improved growth and seed fertility in Arabidopsis plants under B deficient condition . But this strategy, up-regulation of native B transporter to achieve the tolerance to B deficiency, has not been applied for the crop so far. We herein generated several independent lines of transgenic rice plants over expressing rice BOR1 and characterised the phenotypes of these transgenic rice plants under B deficient condition. Rice cultivar Nipponbare was used. Growth experiments were carried out in a green house under natural light condition . After germination on the agar medium containing 0.5 mM CaCl2, seedlings were transferred to a Kimura B hydroponic solution containing 2 mM MES with different B levels: Concentration of B in the solution was 18 µM for B sufficient condition, and 18, 0.18, 0.03 µM for B deficient treatments. Seedlings were grown until grain ripening stage and plant height was measured every other week. At harvest, stackable planters yield components were measured. Concentration of B in flag leaf and husked grain were determined by ICP-MS after digestion using nitric acid and hydrogen peroxide.
Difference in plant height among the B treatments was not clear until 4 weeks after treatments . However, when subjected to lower than 0.18 µM B, reduced plant height was clearly observed according to the growth periods . Visible symptom on leaf blades such as chlorosis was not observed in B deficient-treated plants. On the other hand, the grain yield was greatly reduced by B deficient treatments lower than 0.18 µM B, which was mainly because of decreased numbers of spikelets . Under 0.03 µM B, seedlings showed dwarf phenotype and panicle formation was severely inhibited . Concentration of B in flag leaf and brown rice was also decreased according to the level of B supply . These results suggest that in rice, young seedlings were relatively tolerant to B limited condition, however, continuous low B supply clearly impairs the vegetative and reproductive growth, leading to decreased yields. RT-PCR analysis of 11 independent transgenic lines demonstrated the expression and its variation of introduced gene in transgenic plants . We selected 9 lines with sufficient numbers of seeds and tested the growth under moderate B deficient condition for 2 weeks. The growth of shoots and roots did not differ among 8 transgenic lines and NT . However, among transgenic lines over-expressing introduced OsBOR1, B concentrations in xylem sap of several lines were higher compared to those of NT and transformants with weak expression of introduced gene . These results suggest that increased expression of the rice boron transporter BOR1 enhanced root-to-shoot translocation of boron, which might be resulted in improved B acquisition and further growth under boron deficient condition. Deltas are the pinnacles of life: they provide resources for a diverse array species and it is therefore critical that we protect them. After describing the current issues facing the Sacramento San Joaquin River Delta, CA, US, this report will describe a case study of a water management and agricultural diversification system at Sherman Island which can serve as a demonstration project for future application to deltas around the globe. The magnitude and diversity of California’s agricultural, environmental, industrial, recreational, and urban interests in the Sacramento-San Joaquin Delta emphasize the importance of protecting the Delta infrastructure. Protected by 1,100 miles of levees are over 538,000 acres of farming, 64,000 acres of cities and towns, and 75,000 acres of undeveloped land from flooding and saltwater intrusion the Delta is home to nearly 515,000 people living in seven counties, 500 different plant and animal species, including 20 that are endangered and major transportation and utility infrastructure.
The Sacramento, San Joaquin, Mokelumne, Cosumnes, Calaveras Rivers and their tributaries flow into the Delta and provide water to over 22 million Californians – over two-thirds of the population. Sherman Island sits on the western edge of the Sacramento-San Joaquin River Delta and is one of the key geographic features protecting the Delta as a water resource. The island is located northeast of the city of Antioch, California, and lies within the jurisdiction of Sacramento County. The Sacramento and San Joaquin rivers meet at its western boundary, which is bordered to the northeast by Three-Mile Slough. Levee instability caused by continued subsidence in the region is a severe risk to cause catastrophic failure. If Sherman Island’s levees were to fail water quality for the entire Delta and most of California, would be compromised, most likely on a timescale of years to decades. Because residents rely on the Delta for their drinking water numerous health issues would result from the Delta being compromised. In addition, the livelihoods of those who utilize the freshwater, such as farmers and industry works, could deteriorate. Delta Bearier Engineering estimates the cost to recover lost water supply and to repair levees, infrastructure, and damaged homes in the event of levee failures to be as high as $2.2 trillion . The increased salinity due to saltwater intrusion will also likely destroy populations of wildlife species. The loss of species has the ladder effect on the diet and shelter of other species; thus, whole ecosystems are susceptible to deterioration. Global climate change is a daunting but undeniable reality, the impacts of which must be considered. Engineered systems must be designed with these effects in mind if they are to remain resilient over the entire life span of the project. In considering just how climate change will affect the Sacramento-San Joaquin Delta, it is important to evaluate the following: Sea-Level Rise Numerous scenarios and global climate models have been developed to predict the effect of climate change on global mean sea level . The Intergovernmental Panel on Climate Change gives an estimated increase in GMSL of 0.1 m – 0.9 m between the year 1990 and 2100 . Similarly, a more recent study suggests sea level will rise by as much as 0.5 m to 1.4 m over the course of the next century . There are several implications for Sherman Island and the Delta given these predictions. Governed by significant tidal inflows, the Delta is very susceptible to increased salinity in inland waterways due to rising sea level . This poses a great threat to the viability of Sherman Island and the Delta as a water resource for the State of California. Saltwater intrusion into the lower Delta could compromise water quality, resulting in reduced agricultural yields and greater stresses on alternative water sources. Additionally, a higher mean sea level also means increased pressure on the already fragile levee system.
Levee heights would need to be drastically increased, or else the combination of increased sea level and major storm events would pose an even greater risk to the system. While sea level rise has greater impact on long term water level variations, it is changes in river flow that have the biggest effect on a short-timescale for the Delta . Most predictions indicate that there will be increased flows during the winter months and reduced flows in spring and summer. From a water resource perspective, this implies that less water will be available as the state approaches times of warmer temperature and increasing agricultural demand. Furthermore, reduced spring flows will invite saltwater intrusion further inland into the Delta at a time when even less water will be available to flush the system and maintain the integrity of water supplies. While it is difficult to apply global climate change models to smaller scale regions such as the Delta, it can be inferred from the available studies that wind velocity and intensity will increase in the area. The serious implications of this matter are that wind velocities in the Delta region determine wind and wave action, two factors which have a significant impact on levee erosion . Consequently, levees weakened by wind and waves are subject to greater risk of failure in the event of high water or severe storm. Changes in average temperature and the amount and type of precipitation are also expected as part of global climate change. The amount and timing of annual runoff is one of the biggest impacts, stackable flower pots as precipitation normally falling in the form of snow will turn to rain, reducing the amount of water available for spring flows from snow melt . Increased temperature will have significant effect on the temperature gradient between the San Francisco Bay Area and the Central Valley, further increasing the intensity of wind velocities . Warmer temperatures will also lead to earlier melting of snow, resulting in reduced water availability for an agriculture-dependent state already plagued by drought. Delta system must consider the needs of global climate change including: flood control, agricultural development, water quality, and environmental sustainability. Consequently, efforts must be made to reverse subsidence, stabilize the fragile levee system, increase economic productivity, and protect vital water and environmental resources. The Aquaponics Water Management System combines hydroponics , aquaculture , and restored wetlands enclosed in flood storage zone. The aquaponics system is a bio-integrated system in which waste byproducts from aquaculture are used as nutrients for plant growth in the hydroponics components. Each aquaponics system consists of fish rearing tanks, solids settling and removal tanks, a bio-filter, the hydroponics rafts and a sump. The first step of the aquaponics cycle is fish eat food and excrete ammonia rich effluent. The effluent is sent through the settling tanks to reduce the amount of suspended organic matter. Next the ammonia is removed and bacteria convert ammonia and nitrites to nitrates in the bio-filter. The nitrate rich water is then pumped to the hydroponics component where plants’ roots hang into the pipes and absorb the nutrients from the water. Once water has reached the end of the hydroponics component, it is collected in a sump and then returned back to the rearing tanks.
The water flow through the aquaculture and hydroponics systems is shown in Figure 1. The aquaculture components sit outside of the flood management zone while the hydroponics and wetland systems dwell within. The flood storage zone spans 800 acres and is able to store 12,000 to 16,000 acre-feet of water. Figure 2 displays the approximate layout of the system which consists of floating hydroponics rafts that can move up and down with the variations of the water levels but are anchored to prevent lateral movement. In addition, the flood storage zone provides wetland acreage for wildlife habitat restoration, recreation, carbon sequestration, and subsidence reversal. Levees and Siphons function to enclose the flood storage zone, transport and store water during high river water levels as shown in Figure 3.Levees construction and upgrades are the primary infrastructure needed for the flood storage zone. Levees currently bound the northern, southern, and western edges of the Aquaponics Water Management System. The western and southern edges are bounded by Army Corp Levees protecting the Island from Sacramento and San Joaquin rivers, respectively. The northern edge is bounded by Mayberry Slough levees which are not engineered project levees. Therefore, there is little boring data and high uncertainty of the construction materials and stability. Therefore, a sandy berm will be constructed to filter, and buttress the levees to provide support. The largest infrastructure component to construct is the internal cutoff levee to enclose the flood storage zone by bounding the eastern side. This levee will be constructed 1,160 ft west of the Antioch Bridge, encompassing Scour Lake while maintaining a buffer zone between the system and the maintenance setbacks for the Antioch bridge.