Water Availability In Arid Regions Research Articles

Physiological, Biochemical, Anatomical, and Agronomic Responses of Sesame to Exogenously Applied Polyamines under Different Irrigation Regimes

Polyamines (PAs) are plant growth regulators that attenuate the destructive impacts of water deficit on sesame plants, particularly in arid regions under abrupt climate change. Limited information is available on the physiological, biochemical, anatomical, and agronomic responses of sesame to exogenous application of PAs under water deficit under field conditions. Thus, a two-season field trial was carried out to assess the impact of exogenously sprayed spermine (Spm), spermidine (Spd), and putrescine (Put) on physio-biochemical and anatomical parameters and their influences on agronomic performance and crop water productivity of sesame plants. The sesame plants were assessed under three irrigation regimes; full irrigation (100% ETc), mild drought (75% ETc), and severe drought (50% ETc) conditions. Drought stress displayed negative impacts on all evaluated parameters. However, exogenously applied Pas, especially Put, restricted the destructive effects of water deficit. The application of PAs exhibited highly significant enhancement in photosynthetic pigments (chlorophyll a, b, and carotenoids), gas exchange (net photosynthetic rate, stomatal conductance, and rate of transpiration), water relations (relative water content, membrane stability index, excised leaf water retention), and plant nutrient content (N, P, and K) compared to untreated plants, particularly under severe drought stress. Moreover, PA application displayed highly significant amelioration in osmoprotectants (free proline, soluble sugars, α-Tocopherol, ascorbate, and glutathione), and antioxidant enzyme activities (catalase, peroxidase, superoxide dismutase, ascorbate peroxidase, and glutathione reductase). In addition, foliar nourishing with PAs exhibited a highly significant reduction in oxidative stress markers (malondialdehyde, electrolyte leakage, superoxide, and hydrogen peroxide). These positive impacts of PA application under drought stress were reflected in highly significant improvement in anatomical characteristics (midrib length and width, vascular bundle length and width, thickness of phloem, xylem and collenchyma, vessel diameter, and number of xylem rows in midvein bundle), and yield-related traits (plant height, leaf area, number of capsules per plant, 1000-seed weight, seed yield, and oil content). Consequently, exogenous application of PAs (in particular, Put) could be exploited to enhance the crop water productivity and yield traits of sesame plants under low water availability in arid regions.

Nitrogen rate for cotton should be adjusted according to water availability in arid regions

Recent reports on cotton water use and root-canopy relationship responses to nitrogen (N) fertilizer management under varying water supply in arid regions are limited. This experiment was conducted to estimate cotton water use, root-canopy development, canopy photosynthetic rate (CAP), and yield responses to N application rates under varying water supply levels and to quantify associations between water use processes and N-induced variation in root systems. A two-year field experiment was conducted from 2019 to 2020 at a field site in Xinjiang, China. Cotton root traits and agronomic responses to three N fertilizer application rates (320, 272, and 224 kg N ha −1 ) under two water supply levels (sufficient water supply: 400 mm; limited water supply: 267 mm) were evaluated. Root length density and root dry matter were maximized at 272 kg N ha −1 under sufficient water supply and 320 kg N ha −1 under limited water supply. CAP was strongly associated with crop stage water use induced by root-canopy variation. Under sufficient water, 272 kg N ha −1 substantially increased water use and root growth, slightly inhibited leaf expansion, and substantially improved crop yield compared to 320 and 224 kg N ha −1 . Although net root productivity and live root length declined for 320 kg N ha −1 under limited water supply, yield increase was not limited because of higher CAP and water use induced by the establishment of strong shallow roots. The results demonstrate that moderate N rate (272 kg ha −1 ) under sufficient water supply improves yield through reducing LAI and promoting root growth, while higher N rate (320 kg ha −1 ) under limited water supply achieves high yield through higher CAP, sufficient leaf area, and efficient water uptake under shallow root systems. These findings suggest that both N management strategies and water availability levels should be considered in future efforts to scale from canopy to root level responses in cotton. • The development of roots and canopy jointly determined the water use capacity in crops. • Improving the water use promoted aboveground CAP, dry matter accumulation, and seed cotton yield. • Two N strategies for high cotton yield were proposed under sufficient water and limited water supply. • Root length dynamics from minirhizotron can reflect the crop stage water use during growing season.

WASTEWATER RECLAIMING AND RECYCLING: ESSENCE AND DIRECTIONS FOR IMPLEMENTATION

Topicality. The topicality of the research results from the fact that according to the data of the United Nations (UN), 36% of the world's population lives in water-scarce regions, in particular Ukraine is ranked 125th among 179 countries on the indicator of total internal renewable water resources per capita, which states that Ukraine is poorly supplied with freshwater. In recent years, special attention of international communities have been paid to the wastewater reclaiming and recycling as a possible alternative to traditional water supply and solution of water scarcity problem. In the UN World Water Development Report 2017, it is noted the need to use wastewater as a resource since fresh water has become increasingly scarce. Aim and tasks. The purpose of the article is to determine the essence, features and directions for wastewater reclaiming and recycling implementation to ensure sustainable water resources management in Ukraine. Research results. The results indicate that climate change, rapid urbanization and population growth affect the state of water resources and the population's access to fresh water. In order to find ways to overcome the natural water shortage, it was proposed to use alternative sources of water supply, in particular, wastewater reclaiming and recycling. Based on the analysis of national and foreign regulatory legislation, the modern semantic content of the concepts of "wastewater reclaiming" and "wastewater recycling" has been clarified, and a scheme for introducing the wastewater reclaiming and recycling into the water cycle has been developed. Statistical data on providing the population of Ukraine with centralized water supply and drainage systems and the amount of volumes of untreated wastewater discharged into the environment have been analyzed. The analysis was carried out and the main areas of recycling of wastewater reclaiming components were determined. Conclusion. Considering the importance of ensuring sustainable water resources management, the authors of the article determined the place and role in the introduction of wastewater reclaiming and recycling. The study demonstrated that 97% of Ukraine's wastewater is not recycled, and more than a quarter of the discharged wastewater in the Odessa region is discharged without proper treatment, which has extremely detrimental consequences for the environment and human health. The stages of technological processes of centralized water supply and sanitation services are considered and the introduction of wastewater reclaiming into the water use cycle, in particular in the energy, manufacturing, agricultural sectors and for municipal and domestic needs, is proposed. It is argued that the introduction of wastewater reclaiming and recycling contributes to the development of a circular economy and provides certain socio-economic-environmental benefits, including reducing environmental impact, avoiding overexploitation of water resources and increasing water availability in arid regions of Ukraine.

Optimizing planting density and irrigation depth of hybrid maize seed production under limited water availability

Improvement in seed vigor and yield of hybrid maize is required to ensure food security. Optimal planting density and irrigation depth are critical for hybrid maize seed production in arid areas. Using data from 2012 to 2017, a new integrated model optimized planting density and border irrigation depth for achieving high yield and seed vigor of hybrid maize under limited water availability. For field experiments, a planting density of 9.75 plants m−2 under full irrigation was in the control treatment. The results showed that water deficit decreased yield, evapotranspiration, and aboveground biomass per plant. The highest yield was obtained for the planting density of 12.75 plants m−2 under full irrigation. The single crop coefficient and crop water production function models were modified to simulate evapotranspiration and yield, respectively. Using kernel number per plant and plant growth rate during the flowering stage, a kernel weight model was established. The maximum yield and minimum irrigation depth were weighted and kernel weight was constrained. Three minimum relative kernel weight (RKWmin) options were considered, option 1 with RKWmin= 1.00 (control), option 2 with RKWmin= 0 (unconstrained), and option 3 with RKWmin ranged from 0.60 to 0.90. In option 1, the optimal irrigation depth during the growing season under control planting density decreased by 24.3–39.4% compared to the conventional practices. In option 2, yield increased but average kernel weight decreased by 25% than control. In the option 3, average yield and water use efficiency increased by 9.2% and 6.5% compared to option 1, respectively. The average planting density decreased by 10.2%, yield reduced by 2.0%, and water use efficiency reduced by 1.7%, but kernel weight increased by 9% compared to option 2. Thus option 3 can be recommended for hybrid maize seed production with limited water availability in arid regions of Northwest China. Our research provided a new theoretical method to improve yield, and ensure seed vigor of hybrid maize in arid regions.

Potential for Ground-Based Glaciogenic Cloud Seeding over Mountains in the Interior Western United States and Anticipated Changes in a Warmer Climate

AbstractGlaciogenic cloud seeding has long been practiced as a way to increase water availability in arid regions, such as the interior western United States. Many seeding programs in this region target cold-season orographic clouds with ground-based silver iodide generators. Here, the “seedability” (defined as the fraction of time that conditions are suitable for ground-based seeding) is evaluated in this region from 10 years of hourly output from a regional climate model with a horizontal resolution of 4 km. Seedability criteria are based on temperature, presence of supercooled liquid water, and Froude number, which is computed here as a continuous field relative to the local terrain. The model’s supercooled liquid water compares reasonably well to microwave radiometer observations. Seedability peaks at 20%–30% for many mountain ranges in the cold season, with the best locations just upwind of crests, over the highest terrain in Colorado and Wyoming, as well as over ranges in the northwest interior. Mountains farther south are less frequently seedable, because of warmer conditions, but when they are, cloud supercooled liquid water content tends to be relatively high. This analysis is extended into a future climate, anticipated for later this century, with a mean temperature 2.0 K warmer than the historical climate. Seedability generally will be lower in this future warmer climate, especially in the most seedable areas, but, when seedable, clouds tend to contain slightly more supercooled liquid water.

Modelling Development of Riparian Ranchlands Using Ecosystem Services at the Aravaipa Watershed, SE Arizona

This paper describes how subdivision and development of rangelands within a remote and celebrated semi-arid watershed near the US–Mexico border might affect multiple ecohydrological services provided, such as recharge of the aquifer, water and sediment yield, water quality, flow rates and downstream cultural and natural resources. Specifically, we apply an uncalibrated watershed model and land-change forecasting scenario to consider the potential effects of converting rangelands to housing developments and document potential changes in hydrological ecosystem services. A new method to incorporate weather data in watershed modelling is introduced. Results of introducing residential development in this fragile arid environment portray changes in the water budget, including increases in surface-water runoff, water yield, and total sediment loading. Our findings also predict slight reductions in lateral soil water, a component of the water budget that is increasingly becoming recognized as critical to maintaining water availability in arid regions. We discuss how the proposed development on shrub/scrub rangelands could threaten to sever imperative ecohydrological interactions and impact multiple ecosystem services. This research highlights rangeland management issues important for the protection of open space, economic valuation of rangeland ecosystem services, conservation easements, and incentives to develop markets for these.

Formulating Expectations for Future Water Availability through Infrastructure Development Decisions in Arid Regions

ABSTRACTWater resources development options are usually selected on a least‐cost basis. While economic considerations are dominant in choosing projects, there are also a mix of other factors including social demands, political viability, social equity, and environmental considerations that impact final decisions and development of water supply systems. Understanding local priorities in water resource management decisions can allow for forming expectations of future regional water availability through new infrastructure projects. In this research, we propose that future human mediated water availability in arid regions may be assessed by considering key projects that have been identified or proposed by regional experts and organizations. Using Multicriteria Decision Methods as a framework to organize a set of decision criteria and their relative salience, the likelihood of selection (and development) of a project can be determined and used to form expectations of future regional water availability. We apply this approach in a case study of Jordan, and find that large‐scale desalination projects—that have been in the planning books for decades—are now most likely to be pursued and implemented in the country. Finally, we discuss strengths, limitations, and the general applicability of this method for assessing future water availability in other arid regions.

Stable carbon isotope characteristics of desert plants in the Junggar Basin, China

AbstractDesert plants have unique strategies for survival and growth to cope with the limited water availability in arid regions. The stable carbon isotope (δ13C) provides an integrated measurement of internal plant physiological and external environmental properties affecting photosynthetic gas exchange and water use efficiency. The δ13C values of 84 species in the Junggar Basin were categorized into two groups (ranged from −30.1 to −23.3‰ for C3 and −14.9 to −9.9‰ for C4 species, respectively). No life form differences in δ13C values were detected in C3 (p = 0.78) and C4 plants (p = 0.63). Small differences among life forms were observed in δ13C values in C4 species with shrubs slightly depleted (−13.3‰) relative to perennials (−13.1‰) and annuals (−12.5‰). These differences suggested that δ13C value could not represent a plant functional group classification based on life forms in C4 plants in extremely arid regions. Ephemerals are all using C3 photosynthetic pathway and no significant differences (p = 0.92) in δ13C values were observed between annuals (−26.5‰) and perennials (−26.4‰). The δ13C values of Tulipa iliensis (an important ephemeral species distributed widely in the Junggar Basin) among nine natural populations were positively correlated with leaf (r2 = 0.46, p = 0.046) and soil (r2 = 0.67, p = 0.007) total nitrogen content, and negatively correlated with leaf (r2 = 0.48, p = 0.039) and soil (r2 = 0.79, p = 0.001) water content. This indicated that the variation in δ13C values of T. iliensis was probably caused by both water availability associated stomatal openness and nitrogen availability associated photosynthetic capacity. T. iliensis is very sensitive to water and nitrogen availability in soil.

Economic Feasibility of Wine Grape Production in the Arid US: A Northwest Nevada Example

AbstractAs competition for water resources increases and water availability in arid regions declines, agricultural producers are encouraged to adopt water-conserving strategies. This study examines the economic feasibility of implementing wine grapes in northwest Nevada as a diversification and water conservation strategy. Results show profit potential when vitis interspecific wine grape varieties are produced in the region. Net returns based upon point estimates from two separate analyses show per-acre net returns at $1,065 and $3,022, respectively. However, the large variation in potential net returns shown in the risk analysis, combined with a high capital investment cost of more than $17,000 per acre, may preclude producers from exercising their option to adopt wine grape production. Also, including wine grapes in the on-farm crop portfolio will affect its risk and return characteristics, likely impacting producer preferred level of wine grape adoption. (JEL Classification: Q11, Q15, Q25, Q54)

Modelling tree height to assess climatic conditions at tree lines in the Bolivian Andes

One of the major problems in assessing growth conditions of trees at upper tropical tree lines is that the vast majority of tree lines have been influenced or destroyed by human activities. Confronted with this situation, we modelled tree height of Polylepis trees in the Bolivian Andes correlating field data from 167 Polylepis stands and a climatic model at a resolution of 925 m × 925 m, across a wide range of elevations and tree growth conditions. Overall, mean annual temperature showed the strongest relationship to tree height ( r 2 = 0.73), closely followed by a temperature index summing up temperatures above 6.5 °C ( r 2 = 0.71) and elevation ( r 2 = 0.68). Mean annual precipitation ( r 2 = 0.32), humidity balance ( r 2 = 0.27), potential evaporation ( r 2 = 0.26), and solar radiation ( r 2 = 0.18) all showed much weaker relationships to tree height. However, when we divided the Bolivian Andes into three contrasting bioclimatic regions and used residual tree height (against temperature) as a variable, in the humid NE Bolivian Andes solar radiation was significantly positively related to residuals of tree height, in semi-arid SE Bolivia humidity balance and mean annual precipitation had positive and solar radiation negative influence, and in the arid W cordillera mean annual precipitation had positive influence. Our modelling approach thus confirms the overall predominance of temperatures in determining tree height growth. This temperature-determined pattern is regionally modified by positive effects of increasing water availability in arid regions and of increasing solar radiation in very humid and cloudy regions. This suggests that tree growth is primarily limited by temperatures (ca. 70% of the variance explained), but that water and light availability also play a role (an additional 5%). Accordingly, it appears that there may not be one constant factor limiting tree growth at high elevations, but rather that different tree lines may be affected by different combinations of climatic factors which in turn lead to different ecophysiological effects.

Groundwater Quality Monitoring in Shallow and Deep Aquifers in Saidabad Tahsil Area, Mathura District, India

Water availability in arid regions is both sporadic and highly variable in quantity. If the water quality shows large variations of salinity and concentration of other chemical constituents with depth and time span, it has considerable effect on the entire hydrological set up of the area. In the Saidabad tahsil area, the deep aquifers that supply water to borewells in the alluvial plain of the Mathura region, Uttar Pradesh, have higher salinity than those of the dugwells from the shallow aquifers. The excessive drilling of tubewells and high yield tubewells are resulting in deterioration of water quality of the shallow aquifers. On the contrary, the chemical constituents such as, Na(+), K (+), Cl (-), andHCO (3) (-) show higher concentration in shallow aquifers than deep aquifers. A study carried out to monitor water quality in this region reveals that the groundwater quality varies with depth and time span in shallow and deep aquifers. Factors controlling variations in salinity and concentration of chemical constituents of the water in the two types of aquifers are discussed. The relative merits of the shallow water for potability are pointed out with respect to salinity concentrations and public health.

"Improved" Sand Dams for Wildlife Habitat Management

WEAVER Suggestions for improving the efficiency, dependability, and simplicity of the sand dams des&%ed by Sivils and Brock (1981) are presented. Recommendations which may result in decreased installation and maintenance costs are included. Sivils and Brock (198 I) recently presented suggestions for the development of sand dams to increase water availability in arid regions. While the idea is not new (see Halloran and Deming 1956, 1958), its presentation is timely because earlier designs failed to incorporate subterranean, soil-free reservoirs. The design of Sivils and Brock, however, is not without potential flaws and is unnecessarily complicated. We, therefore, offer suggestions for improving the efficiency and dependability of such devices, while simultaneously increasing their simplicity. The most vulnerable part of the system is the float valve. Float valve failures have been a major problem in guzzlers installed for mountain sheep in California (Bleich et al. 1979). They are subject to jamming by foreign objects, including sand particles, organic material, or small rocks, which may lodge in the valve seat, causing the valve to stay open and drain the stored water. To minimize this possibility a 30-cm (l-foot) length of capped 15-cm diameter well screen (Johnson Screen) should be connected via a bell reducer to a SO-mm (2-inch) outlet pipe on the upstream side of the dam. Such a screen will prevent particles larger than 0.75 mm from entering the drinker line, thereby decreasing the chance of a float valve failure. Replacing the pipe passing through the dam, should it be broken by falling rocks (Bleich et al. 1979), is difficult. We recommend that the outlet pipe be galvanized material; if desired, the drinker line, which is more easily replaced, may be plastic. It is unnecessary to plumb the collecting culverts into a common outlet, as suggested by Sivils and Brock, because stored water will naturally seek the lowest point behind the dam, flowing through rocks, sand, the Johnson Screen, the outlet pipe, and into the drinker line. Of course, the outlet must be located at the lowest possible point on the dam. The time and money saved by not plumbing the culverts to a common point may be substantial. If a relatively high dam is to be constructed, the culverts may be “layered’* to increase storage capacity. Again, the water level in the culverts will decrease as water is used at the drinker. In order to minimize potential damage from initial heavy food flows, layered culverts should be bolted together, and the bottom layer should be attached to the rock substrate with rebar or other suitable material. Once the dam has naturally backfilled with sand and gravel, this The authors are associate wildlife biologist, California Department of Fish and Game. P.O. Box 1741, Hemet 92343; and associate wildlife biologist, California Department of Fish and Game. 1416 Ninth Street, Sacramento 95814. This report is a contribution from California Federal Aid in Wildlife Restoration Projects W-26-D (Wildlife Habitat Development) and W-51-R (Big Game