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To further evaluate the effect of water stress on soil respiration (RS), reveal the influencing factors of daily and seasonal RS, and systematically evaluate and compare the sensibility of different machine learning algorithms (multiple nonlinear regression [MNR], support vector machine regression [SVR], backpropagation artificial neural network [BPNN]) to estimate RS from a maize field under water stress condition, the field experiments were conducted within a maize field in Inner Mongolia, China, during the entire 2019 growing season. Various levels of deficit irrigation were conducted in the vegetative, reproductive, and mature stages. Our research indicated that soil CO2 fluxes from 100% evapotranspiration treatment (Tr1) were significantly greater than various deficit irrigation treatments (Tr2, Tr3, Tr4) during each growth stage of summer maize. The cumulative soil CO2 fluxes of Tr2, Tr3, and Tr4 decreased 24.8%, 30.3%, and 43.7% compared with Tr1, respectively. We determined that the drivers affecting the daily RS were soil temperature at 5 cm depth (TS,5) and soil surface temperature (TSF), followed by water‐filled porosity (WFPS) at 5 cm depth, but no significant correlations were observed at 25 cm depths. TS,5 and TSF also performed similar correlation with seasonal RS with R greater than 0.753 among all water treatments, followed by chlorophyll content with R greater than 0.726. During the whole growing season, the BPNN model exhibited the best predicting result, and could explain the 60%–80% and 87.8% of the variations of RS at the daily and seasonal scales, with root mean square error of 48.7–100.9 mg m−2 h−1 and 91.5 mg m−2 h−1, respectively. The SVR and MNR models could estimate the 47.9%–57% and 39.9%–52.1% of the daily RS and 81.4% and 78.6% of the seasonal RS, respectively. Overall, our study indicated the machine learning algorithms could be successfully applied to estimate RS at daily and seasonal scales from a maize field under water stress condition. [ABSTRACT FROM AUTHOR]

As competition for limited water resources in the western United States and other arid and semiarid regions intensifies, there is a need to provide alfalfa (Medicago sativa) growers with knowledge of how water‐optimizing practices impact alfalfa nutrient use. The objective of this research was to evaluate how three water management strategies, and their interactions, influence alfalfa K and P concentration, uptake, uptake efficiency, and internal use efficiency. Alfalfa cultivars, deficit irrigation, and irrigation technologies were tested at two sites in Utah during 2020–2021. A single drought‐tolerant (DT) cultivar ('Ladak II') was compared to a conventional alfalfa cultivar specific to each location. Four irrigation rates (100%, uniform reductions of 25% and 50%, and a targeted reduction of ∼50%) were nested within five pivot irrigation technologies. Few alfalfa K and P nutrient dynamics responded to the interactions of cultivar and rate or technology. Nutrient responses to the irrigation technologies were strongly associated with the technology effect on alfalfa yield such that uptake efficiency was sometimes greater with low‐elevation sprinkler technologies. The K and P responses to deficit irrigation were most pronounced at the uniform or targeted 50% irrigation rate. Alfalfa cultivar had the least impact on alfalfa K and P dynamics, and the DT cultivar never improved uptake or efficiencies. These results indicate that few adjustments in K and P management may be needed with the three water optimization approaches evaluated in this study. The most notable is that K and P fertilizer input can likely be reduced with severe deficit irrigation. Core Ideas: There is a need to identify how combinations of water optimization practices influence alfalfa nutrient management.Irrigation technology and alfalfa cultivar had minor effects on alfalfa K and P dynamics.Irrigation rate had the largest impact on K and P efficiency and use with less irrigation increasing efficiency.K and P fertilizer applications can likely be reduced under deficit irrigation strategies. [ABSTRACT FROM AUTHOR]

The increase in crop yield can be primarily attributed to the combined effect of genetic advancements, as well as increased contributions from nitrogen (N) and water. The accumulation of dry matter plays a crucial role in determining grain yield in winter wheat. The current study aimed to better understand the source‐sink dynamics, analyse the dry matter transport (DMT) before and after anthesis and calculate its ratio to grain yield. In this experiment, eight main cultivars of winter wheat that have been widely cultivated in Shaanxi Province since the 1940s were selected as planting material. Field examinations were conducted using three levels of both irrigation and N. The yield‐related parameters, dry matter accumulation, dry matter distribution, DMT and DMT efficiency were measured. The results showed that irrigation prolonged the time of dry matter accumulation, and the application of N fertiliser increased the rate of dry matter accumulation. The analysis of the dynamic characteristic parameters of dry matter in winter wheat showed that irrigation and N had a significant impact on rate of dry matter accumulation. The proportion of stems, leaves and spikes of new varieties increased significantly (p < 0.05), which increased by 56.67%–69.7%, 13.26%–18.07% and 15.78%–28.26%, respectively, with the varietal improvement. The DMT efficiency increased with varietal improvement and also with increased irrigation and N application. The response of irrigation treatment to DMT and dry matter was more significant. In addition, the irrigation treatment had a higher effect on the DMT efficiency of vegetative organs after anthesis. The logistic equation analysis revealed that water stress accelerated the fulfilment of maximum daily temperature (Tmax), while both the maximum growth rate (Gmax) and dry matter weight (Wmax) decreased as water stress increased. There was a positive linear relationship between dry matter accumulation after anthesis and grain yield. The structural equation model showed that varieties, N application and irrigation had significant positive effects on DMT, post‐anthesis dry matter and grain yield, while irrigation had significant negative effects on DMT efficiency. The accumulation of dry matter in winter wheat after anthesis showed a significant increase with the succession of varieties. The combination of moderate deficit irrigation and fertilisation improved transportation and dry matter accumulation after anthesis in winter wheat, thereby enhancing its production capacity. [ABSTRACT FROM AUTHOR]

Improving drought resistance in Zoysiagrass (Zoysia spp.) is a target for both private and public breeding programs. The performance of 26 elite experimental zoysiagrasses was compared under progressive drought stress with Palisades, Diamond, and Zeon. Environmental conditions were warmer and drier in 2020 (66 days) than 2021 (45 days). Irrigation was applied once weekly using potential evapotranspiration (ETo) rates and crop coefficients (Kc) of 0.6 (non‐stress), or 0.40, 0.30, and 0.25 deficit treatments. Turfgrass quality, leaf wilt, normalized difference vegetative index, normalized difference red edge, and volumetric water content were recorded weekly. Genotypes with the highest means (statistical “a” group) contributed to a turfgrass performance index (TPI). Elite zoysiagrass with TPI ≥ Palisades (19) were Zoysia japonica Steud. ecotypes DALZ 1311 (22), 1601 (19), and 1603 (21), and finer textured interspecific hybrids, DALZ 1701 (18), 1713 (26), 1714 (18), and 1801 (24). Relative to an irrigation schedule using a 0.6 Kc, these genotypes survived extreme deficit irrigation, which conserved 40.1% (45,859.6 L) and 66.4% (44, 592.2 L) of water in 2020 and 2021, respectively. Overall, this study demonstrated that significant water consumption could be reduced with proper cultivar selection and deficit‐based irrigation management while maintaining an acceptable turfgrass quality under drought conditions. [ABSTRACT FROM AUTHOR]

Water deficit priming through regulated deficit irrigation has been shown to be beneficial for peanut cultivation, leading to improved water‐use efficiency during the crop cycle and enhanced stress acclimation. The effects of priming using water deficit can be heritable, but little is known about stress priming effects on the physiology and growth of successive generations undergoing water stress. Two experiments were conducted to assess cross‐generational priming by determining physiological and growth responses of offspring of primed and non‐primed peanut plants of two genotypes, COC‐041 and New Mexico Valencia C (NMV‐C), both previously found to be strongly responsive to priming. Seeds were collected from parental plants subjected to mild water stress by regulated deficit irrigation (primed) or adequate irrigation (non‐primed). These seeds were then planted, and the offspring were monitored for physiological and growth responses to water stress, including on a whole‐plant basis using a high‐throughput physiological phenotyping platform and on individual leaves by periodic single‐leaf measurements. Measurements included whole‐plant transpiration (plant‐Tr), root water uptake, leaf transpiration, stomatal conductance and net CO2 assimilation (leaf‐Tr, leaf‐gs, and leaf‐A), leaf water and osmotic potential (leaf‐Ψw and leaf‐Ψo), leaf osmotic adjustment, leaf relative water content (leaf‐RWC) and cumulative plant‐Tr. Offspring of both genotypes from primed parent plants had faster early establishment, with more uniform germination, and more rapid initial seedling growth compared to offspring from non‐primed parent plants. Although offspring of both non‐primed and primed plants of both genotypes exhibited a significant reduction of plant‐Tr, gas exchange, leaf‐Ψw, leaf‐Ψo, and leaf‐RWC when exposed to water stress, offspring of primed plants showed increased water use efficiency through reduced leaf‐gs, leaf‐Tr and plant‐Tr while maintaining leaf‐A under water stress. Despite offspring of both primed and non‐primed plants being susceptible to severe water stress, offspring of primed plants exhibited overall enhanced water use efficiency, leading to greater dry biomass production per gram of transpired water and a trend of less growth reduction due to water stress compared to offspring of non‐primed plants, especially for the genotype COC‐041. This study shows the potential of water deficit priming to promote cross‐generational changes in physiological function under limited water availability, by enhancing crop stress acclimation in the next plant generation. [ABSTRACT FROM AUTHOR]

The impact of drought stress on productivity of cotton (Gossypium hirsutum L.) is a well‐known challenge in agricultural production, and concurrently, the question of whether using the same or different selection criteria in well‐watered and water‐deficit conditions to select drought‐tolerant cotton varieties remains unclear. This study aimed to comprehensively assess the single plant progeny lines within the F6 and F7 generations for determine response to DS and select the tolerant lines within the F7 generation. Single plant progeny rows were established, with the deficit water condition comprising 108 and 136 single plants for the F6 and F7 generations, respectively, and the WW condition consisting of 120 and 156 single plants for the F6 and F7 generations, respectively, with four blocks in Augmented experimental design. These progeny rows have length of 12 m, incorporate five control varieties (Karizma, Gloria, Carla, Candia and Claudia) to facilitate a comprehensive comparison. The study findings showed that fibre length, boll number and lint percentage were identified as the most crucial selection criteria under both WW and deficit irrigation conditions through principal component analysis. These indicators are highly beneficial for evaluating cotton's drought tolerance and screening potential drought‐tolerant lines under both irrigation scenarios. According to the decision tree analysis, FL and BN have emerged as the most critical decision‐making parameter in both irrigation conditions. Furthermore, the analysis revealed that each selection criterion has different impact in the comprehensive selection process. Also, as a result of all statistical analysis results and breeder observations, a total of 10 cotton lines were selected in the F7 generation. These selected genotypes hold promise for future cotton breeding programmes, providing an avenue to enhance drought tolerance and elevate cotton yield and productivity. Clinical Trial Registration: This study does not involve a clinical trial, and therefore, clinical trial registration is not applicable. [ABSTRACT FROM AUTHOR]

The article focuses on the impact of water stress on cropping decisions in the Cauvery Delta Region of India. Topics include the influence of groundwater and surface water availability on crop choice, farmers' responses to market demands and water scarcity, and the broader socio-environmental factors affecting agricultural practices.

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Surplus wastewater accumulates in winter and requires a discharging solution. In our study we examined the effects of using treated wastewater (TWW) as supplemental pasture irrigation in winter. To test the effect of TWW irrigation on the vegetation and soil, 10 grazing prevention exclosures were established at Ramat‐Hanadiv Park, Israel, with half of them irrigated with TWW. Soil and vegetation were sampled during 2 years of irrigation and 1 year after cessation of irrigation. Vegetation composition, species richness, and productivity were sampled at the peak of the growing season and various indices of herbage quality were measured. Our results show that irrigation with wastewater increased herbage production by an average of 38% and total pasture protein production by 9% relative to the control subplots. Conversely, TWW irrigation decreased plant protein content while increasing herbage fibre content and lowering its digestibility. Over a period of 2 years, species richness decreased in the irrigated subplots. Most of the soil indices examined were not affected by irrigation, but in the irrigation subplots, sodium values and the sodium adsorption‐ratio were higher than in areas without irrigation. Additional resources in winter enabled the plants to grow rapidly and increased interplant competition. Changes in vegetation composition were revealed through functional group reshuffling and species richness decline. The results of our study show that wastewater irrigation causes an increase in productivity but a decrease in forage quality. At the pastoral system level, the significant increase in productivity leads to increased availability of protein and herbage for animals. [ABSTRACT FROM AUTHOR]

Commercial cultivars with advanced technology have reduced pest pressures, while greater seed costs have increased total production cost. Limited information is available on the optimal final population density (PD) for the commercially available cotton (Gossypium hirsutum L.) cultivars with advanced technologies in water‐scarce environments. Therefore, our objectives were to examine the effects of PD on cotton growth and development, lint yield, fiber quality, and net return. A 2‐year study was conducted to test four PDs (low, medium, high, and very high) in deficit‐irrigated and dryland conditions at Chillicothe, TX. Final PD at 12 days after planting were 54,078, 109,563, 124,037, and 151,377 plant ha−1 in irrigated and 67,346, 115,335, 116,397, and 145,432 plant ha−1 in dryland trials. Maturity was delayed in the low PD early in the season; however, the differences on maturity ceased toward the end of the season. No statistical differences were observed on lint yield and fiber quality among treatments in irrigated and dryland trials. Average lint yields were 1199 kg ha−1 in irrigated and 796 kg ha−1 in dryland trial. Net returns were similar among all PD in the irrigated trial, while low PD had significantly higher net‐return than very high PD in the dryland trial. The higher net return at the low PD was due to the lower seed cost associated with a low seeding rate. In the water‐scarce environment, final plant density of 54,078 plant ha−1 in deficit irrigation and 67,346 plant ha−1 in dryland produced optimal yield and net return as compared to higher PD examined. Core Ideas: We examined the effects of plant density on cotton growth and development, lint yield, fiber quality, and net return.No statistical differences were observed on lint yield and fiber quality among treatments in irrigated and dryland.Net returns were similar among all PD in the irrigated trial, while low PD had significantly higher net‐return than.The higher net return at the low PD was due to the lower seed cost associated with a low seeding rate. [ABSTRACT FROM AUTHOR]

Potassium (K+) is an essential macronutrient for appropriate plant development and physiology. However, little is known about the mechanisms involved in the regulation of leaf water relations by K under water deficit. A pot experiment with two K supplies of 0.45 and 0 g K2O per pot (3 kg soil per pot) and two watering conditions (well‐watered and water‐deficit) was conducted to explore the effects of K deficiency on canopy transpiration characteristics, leaf water status, photosynthesis, and hydraulic traits in two rice genotypes with contrasting resistance to drought. The results showed that K deficiency reduced canopy transpiration rate by decreasing stomatal conductance, which led to higher canopy temperatures, resulting in limited water deficit tolerance in rice. In addition, K deficiency led to further substantial reductions in leaf relative water content and water potential under water deficit, which increased the imbalance in leaf water relations under water deficit. Notably, K deficiency limited leaf gas exchange by reducing leaf hydraulic conductance, but decreased the intrinsic water use efficiency under water deficit, especially for the drought‐resistant cultivar. Further analysis of the underlying process of leaf hydraulic resistance revealed that the key limiting factor of leaf hydraulic conductance under K deficiency was the outside‐xylem hydraulic conductance rather than the xylem hydraulic conductance. Overall, our results provide a comprehensive perspective for assessing leaf water relations under K deficiency, water deficit, and their combined stresses, which will be useful for optimal rice fertilization strategies. [ABSTRACT FROM AUTHOR]

Families commonly document their outings by capturing their experiences through digital photographs and videos. However, little is known about the ways in which families engage their personal mobile devices to document educational family outings and how they subsequently talk about the digital artifacts that captured their informal learning experiences. This paper presents new evidence on family digital artifact creation during an informal science institution (ISI) visit, the expected and actual uses of their digital artifacts after the visit, and family conversations reminiscing about the ISI visit with the digital artifacts. Using a concurrent triangulation mixed‐methods design, data on family digital artifact creation during an aquarium visit (N = 204) and digital artifact use after the visit (n = 67) were collected using parent surveys. Audio‐recorded parent‐child conversations with a subset of families (n = 25) document whether and how families use their digital artifacts to reminisce about the aquarium visit. Quantitative findings detail family digital technology practices during informal learning experiences, and qualitative findings suggest evidence of informal science learning in the everyday interactions of the families who elected to continue the study. The study indicates that family storytelling and digital technology practices may help to bridge informal science learning from ISI to home and frames family non‐participation within an anti‐deficit perspective. [ABSTRACT FROM AUTHOR]

Clay‐rich rocks are integral to subduction zone dynamics and of practical importance, for example, as barriers in nuclear waste and CO2 repositories. While the effects of swelling strain on the self‐sealing capabilities of these rocks are relatively well‐established, the implications of polar fluids interacting with charged clay particles on the frictional behavior, and the role of swelling stress in initiating slip in critically stressed faults, remain ambiguous. To address these uncertainties, we conducted triaxial friction experiments using saw‐cut samples, with the upper half composed of Opalinus claystone (OPA) and the lower half of Berea sandstone (BER). The frictional strength of the non‐wetted OPA‐BER interface was estimated based on experiments at confining pressures of 4–25 MPa and constant axial loading rate (0.1 mm/min). Fluid injection friction experiments were performed using decane (non‐polar fluid) or deionized water (polar fluid) at 10 and 25 MPa confining pressures and constant piston displacement control. Macroscopic mechanical data were complemented by distributed strain sensing on the sample surface. Compared to decane, the frictional strength of the OPA‐BER interface tended to decrease when injecting water, which is attributed to phyllosilicate lubrication and the transition of the OPA from a solid rock to an incohesive mud near the saw‐cut surface. When injecting water, slip was initiated during initial hydration of the OPA‐BER interface, although the apparent stress state was below the yield stress. To explain this behavior, we propose that the swelling stress is a crucial factor that should be integrated into the effective stress model. Plain Language Summary: Clay‐rich rocks are important in subduction zones and for practical applications like nuclear waste containment and CO2 storage. A unique property of clay is the ability to swell by incorporation of water. If swelling deformation is constrained, swelling stress can develop. While the enhanced sealing ability of fractures due to swelling is well‐known, the effect of water‐clay interactions on friction and the contribution of swelling stress to fault reactivation remain unclear. We studied these effects with laboratory experiments where Opalinus claystone (OPA) was sheared against Berea sandstone. First, using experiments without fluids, we established that our set‐up is representative for claystones. In further experiments, we injected a non‐polar fluid that does not interact with clay. We compared these with experiments where we injected water, which is polar and therefore interacts with the charged clay. The frictional strength tended to decrease when injecting water, likely due to water acting as a lubricant and transforming OPA into a slurry. Surprisingly, movement along the interface started although the applied stress was below the threshold. We explain this by the contribution of swelling stress to the overall stress state. These findings improve our understanding of clay‐rich rock behavior in nature and practical applications. Key Points: The frictional strength of clay‐rich rocks tends to decrease in the presence of a polar fluid compared to a non‐polar fluid or no fluidFrictional slip in clay‐rich rocks may be initiated although the apparent effective stress state is below the yield stressH2O‐clay interactions may contribute to reactivation of faults by altering the mechanical properties and the build‐up of swelling stresses [ABSTRACT FROM AUTHOR]

Reservoir is a vital tool for human utilization of water resources, and the deterioration of its water quality can seriously threaten the water cycle and sustainable urban development. However, there are relatively few studies in academia that analyse and evaluate the water quality of multiple reservoirs at the same time. To address this knowledge deficit, we collected 108 water samples from three different reservoirs in Chuzhou City for 36 months (from 2019 to 2021), explored the drivers of changes in water quality parameters over time and the extent of eutrophication. Our results indicated that the water quality of the reservoirs was deteriorating during the study period, among which Huanglishu Reservoir and Shahe Reservoir reached mild eutrophic status, and both had higher eutrophication levels than Chengxi Reservoir. Secchi depth, total nitrogen and total phosphorus were the principal factors inducing eutrophication. The biassed utilization of reservoir functions was the major contributor to the discrepancy in the degree of eutrophication. Furthermore, Pearson correlation analysis revealed that there are significant correlations between many water quality parameters. Cluster analysis grouped the 12 months of each year into three clusters (stable water level period, rainy season high flow period and winter low flow period). Based on this, analysis of variance showed that most water quality parameters varied considerably between the clusters. Collectively, this study identified the actual water quality conditions of three reservoirs in Chuzhou City and provided guidance for local water quality management and environmental protection. [ABSTRACT FROM AUTHOR]

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The changing climate makes it more difficult to manage water resources and food production sustainably. Various adaptation measures have been proposed to moderate the negative impacts of climate change; however, implementation of these measures may be hampered by other factors even if the benefits are acknowledged—a situation termed "soft adaptation limits" by the IPCC. We hypothesized that societal rules can be a potential barrier to adaptive action if they are too fixed, because such rules have coevolved with the interactions between the past climate and human activities. To test this hypothesis, we present a framework based on the assumption that associated societal rules of Japan's matured irrigation systems are potential barriers to adaptation. The framework consisted of two process‐based models, one to evaluate the water deficit risk and one to evaluate the benefits of optimizing rice yield and quality. We applied each model to an experiment in which we shifted the current transplantation date by 1 week for up to 5 weeks before and after the current date under the historical (1981–2000) and RCP 2.6 and 8.5 (2011–2030 and 2031–2050) scenarios. We revealed two contrasting development pathways in the study watershed. Soft adaptation limits imposed by water availability will occur by 2030 if farmers optimize for quality, whereas mutual benefits to farmers and river administrators will be achieved if farmers seek yield. We argue that more participatory research with stakeholder engagement, as well as policy discussions about these possible developments, is needed to ensure successful adaptation. Key Points: We present a framework for examining whether societal rules of Japan's matured irrigation systems are potential barriers to adaptationWe show that potential barriers to adaptation imposed by water availability will occur if farmers optimize for rice qualityWe argue that more participatory research with stakeholder engagement is needed to ensure successful adaptation [ABSTRACT FROM AUTHOR]

Increasing N use efficiency (NUE) is desirable in turfgrass management. Traditional definition of NUE in turfgrass is essentially the inverse of nitrogen concentration in the clippings and is often evaluated once in a growing season. In this experiment, we followed the Brenderse and Aerts' definition of NUE as the product of mean residence time (MRT) and nitrogen productivity (NP). The objective of this experiment was to identify NP changes over time in Kentucky bluegrass cultivars at different N levels under deficit irrigation. Nine Kentucky bluegrass (Poa pratensis L.) and two hybrid bluegrass cultivars from 10 phenotypic classes were tested under N rates of 10 and 40 g m−2. Deficit irrigation at 60% of the evapotranspiration was imposed. The results showed interaction effects on NP from N level, irrigation, and cultivar. Low‐N treatment resulted in higher NP values as compared to high‐N for 'Merit' and 'Martha'. No NP difference existed between N or irrigation levels for 'Blue ghost', 'Geronimo', 'Heidi', 'Bandera', 'Impact', 'Fielder', 'Jackrabbit', and 'Park'. 'Rhythm' showed lower NP values in high‐N combined with full irrigation compared to other treatments. In general, increasing N levels resulted in lower NP, but higher nitrate reductase activity (NaR) and higher net photosynthesis. No N by irrigation interaction effect was detected for effective quantum yield or NaR. In conclusion, leaf‐level NP was shown to be an effective parameter for in‐season monitoring of the above‐ground NUE of Kentucky bluegrass, which provided more dynamic information than clipping yields or a one‐time NUE calculation based on traditional definition. [ABSTRACT FROM AUTHOR]

Nitrous oxide (N2O) exacerbates the greenhouse effect and thus global warming. Agricultural management practices, especially the use of nitrogen (N) fertilizers and irrigation, increase soil N2O emissions. As a vital sector of global agriculture, specialty crop systems usually require intensive input and management. However, soil N2O emissions from global specialty crop systems have not been comprehensively evaluated. Here, we synthesized 1137 observations from 114 published studies, conducted a meta‐analysis to evaluate the effects of agricultural management and environmental factors on soil N2O emissions, and estimated global soil N2O emissions from specialty crop systems. The estimated global N2O emission from specialty crop soils was 1.5 Tg N2O‐N year−1, ranging from 0.5 to 4.5 Tg N2O‐N year−1. Globally, soil N2O emissions exponentially increased with N fertilizer rates. The effect size of N fertilizer on soil N2O emissions generally increased with mean annual temperature, mean annual precipitation, and soil organic carbon concentration but decreased with soil pH. Global climate change will further intensify the effect of N fertilizer on soil N2O emissions. Drip irrigation, fertigation, and reduced tillage can be used as essential strategies to reduce soil N2O emissions and increase crop yields. Deficit irrigation and non‐legume cover crop can reduce soil N2O emissions but may also lower crop yields. Biochar may have a relatively limited effect on reducing soil N2O emissions but be effective in increasing crop yields. Our study points toward effective management strategies that have substantial potential for reducing N2O emissions from global agricultural soils. [ABSTRACT FROM AUTHOR]

The basic partitioning of precipitation P into evapotranspiration ET and run‐off Q is known as the "central problem of hydrology." ET depends primarily on precipitation, P, and potential evapotranspiration, PET, which are connected by the biological process of photosynthesis. Photosynthesis is the fundamental step underlying the productivity of plant ecosystems. An important measure of plant productivity is the creation of plant biomass, which is quantified by net primary productivity, NPP. NPP is most parsimoniously related simply to the evapotranspiration, ET. The dependence of NPP (ET) appears to be in the form of a power law with an upper limit derived from the maximum plant‐available solar energy accessible on Earth. However, theoretical, rather than phenomenological, treatments relating ET and its complementary variable, run‐off (P − ET ≡ Q) to climate variables that measure the available energy (PET) and available water (P) (known as the water balance) are, at best, scarce, and their continued application to predicting NPP (P, PET) even more so. One theory developed recently to predict the water balance is based on determining how to divide P into Q and ET in such a way as to maximize NPP. Substitution of the resulting optimized ET (P, PET) into the function NPP (ET) then yields NPP (P, PET). We investigate the possibility that this new theoretical framework, which yields ET(P, PET) based on ecological optimality and percolation theory, can predict the dependence of NPP (P, PET). If the prediction of NPP (P, PET) is verified, this result may lead to significant progress in other areas, including the problem of the chief causes of geographical variability of species richness. Key Points: A novel approach linking evapotranspiration ET to climate variables is now applied to net primary productivity NPPET was obtained from the maximum NPP for given climatic conditions, consistent with maximum diversityResulting predictions of NPP as functions of precipitation P and potential evapotranspiration PET agree with observation [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the drought tolerance of four different genotypes, including two wheat varieties (Ceyhan 99 and Sagittario) and two wheat lines (Zdeb101 and Zdeb102), and create irrigation schedules. This study was performed with treatments applied at three irrigation levels (S100: treatment where the entire water need of the plant was met, S50: 50% of the water provided in the S100 treatment, S0: Rainfed), with four genotypes and four replications in a split‐plot design in Kahramanmaras East Mediterranean Transitional Zone Agricultural Research Institute in 2019 and 2020. The Ceyhan 99 and Sagittario varieties, which are widely cultivated in the region and the Zeb101 and Zdeb102 lines that are candidates for varieties were used in the study. In the study, 217.1 and 213.77 mm of water was given to S100, 108.54 and 106.88 mm of water was given to S50, and no irrigation was provided to S0 in 2019 and 2020, respectively. The effects of different irrigation levels on yield, water use efficiency (WUE), irrigation water use efficiency (IWUE), protein content and wet gluten content were investigated. At the end of this study, seasonal evapotranspiration (ET), irrigation water and yield decreased from S100 to S0. WUE, IWUE and yield response factor (Ky) values showed different trends in both years. There was no significant difference in yield between the varieties. However, in the stress susceptibility index (SSI) analyses of the genotypes, it was found that the most drought‐tolerant genotypes were Zdeb102 (0.50) and Ceyhan 99 (0.54). The highest protein content and wet gluten content were found as 11.38% and 22.24% in the Sagittario variety, respectively. It is recommended that Zdeb102 and Ceyhan 99 be cultivated in regions such as Kahramanmaras which have semi‐arid climate characteristics in the Mediterranean. [ABSTRACT FROM AUTHOR]

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Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Biochar addition strongly alters net carbon (C) balance in agroecosystems. However, the effects of biochar addition on net C balance of maize field under various irrigation water quantities and qualities remains unclear. Thus, a field experiment combining two irrigation levels of full (W1) and deficit irrigation (W2 = 1/2 W1), two water salinity levels of fresh (S0, 0.71 g L−1) and brackish water (S1, 4 g L−1), and two biochar addition rates of 0 t ha−1 (B0) and 60 t ha−1 (B1) was conducted to investigate soil carbon dioxide (CO2) emissions, maize C sequestration and C budget. RESULTS: Compared with W1, W2 reduced average cumulative CO2 emissions by 6.5% and 19.9% for 2020 and 2021, respectively. The average cumulative CO2 emissions under W1S1 treatments were 5.4% and 22.3% lower than W1S0 for 2020 and 2021, respectively, whereas W2S0 and W2S1 had similar cumulative CO2 emissions in both years. Biochar addition significantly increased cumulative CO2 emissions by 17.8–23.5% for all water and salt treatments in 2020, and reduced average cumulative CO2 emissions by 11.9% for W1 but enhanced it by 8.0% for W2 in 2021. Except for W2S1, biochar addition effectively increased total maize C sequestration by 6.9–14.8% for the other three treatments through ameliorating water and salt stress over the 2 years. Compared with W1S0, W1S1 did not affect net C sequestration, but W2 treatments significantly decreased it. Biochar addition increased net C sequestration by 39.47–43.65 t C ha−1 for four water and salt treatments for the 2 years. CONCLUSION: These findings demonstrate that biochar addition is an effective strategy to increase both crop C sequestration and soil C storage under suitable water‐saving irrigation methods in arid regions with limited freshwater resources. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Elicitors induce defense mechanisms, triggering the synthesis of secondary metabolites. Irrigation has implications for a more sustainable viticulture and for grape composition. The aim was to investigate the influence on grape aroma composition during 2019 and 2020 of the foliar application of amorphous calcium phosphate (ACP) nanoparticles and ACP doped with methyl jasmonate (ACP‐MeJ), as an elicitor, with rainfed or regulated deficit irrigation (RDI) grapevines. Results: In both growing seasons, nearly all terpenoids, C13 norisoprenoids, benzenoid compounds and alcohols increased with ACP‐MeJ under the RDI regimen. In 2019, under the rainfed regime, ACP treatment increased limonene, p‐cymene, α‐terpineol, 1,1,6‐trimethyl‐1,2‐dihydronaphthalene (TDN), 2‐ethyl‐1‐hexanol, (E,E)‐2,4‐heptadienal, and MeJ concentration in comparison with control grapes. In 2020, the rainfed regime treated with ACP‐MeJ only increased the nonanoic acid content. Grape volatile compounds were most influenced by season and watering status whereas the foliar application mainly affected the terpenoids. Conclusion: A RDI regime combined with the elicitor ACP‐MeJ application could improve the synthesis of certain important volatile compounds, such as p‐cymene, linalool, α‐terpineol, geranyl acetone, β‐ionone, 2‐phenylethanol, benzyl alcohol, and nonanoic acid in Monastrell grapes. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Alternate wetting and drying irrigation (AWD) has been shown to decrease water use and trace gas emissions from paddy fields. Whereas genotypic water use shows little variation, it has been shown that rice varieties differ in the magnitude of their methane emissions. Management and variety‐related emission factors have been proposed for modelling the impact of paddy production on climate change; however, the magnitude of a potential reduction in greenhouse gas emissions by changing varieties has not yet been fully assessed. AWD has been shown to affect genotypic yields and high‐yielding varieties suffer the greatest loss when grown under AWD. The highest yielding varieties may not have the highest methane emissions; thus, a potential yield loss could be compensated by a larger reduction in methane emissions. However, AWD can only be implemented under full control of irrigation water, leaving the rainy seasons with little scope to reduce methane emissions from paddy fields. Employing low‐emitting varieties during the rainy season may be an option to reduce methane emissions but may compromise farmers' income if such varieties perform less well than the current standard. Methane emissions and rice yields were determined in field trials over two consecutive winter/spring seasons with continuously flooded and AWD irrigation treatments for 20 lowland rice varieties in the Mekong Delta of Vietnam. Based on the results, this paper investigates the magnitude of methane savings through varietal choice for both AWD and continuous flooding in relation to genotypic yields and explores potential options for compensating farmers' mitigation efforts. [ABSTRACT FROM AUTHOR]

BACKGROUND: Table olives are widely consumed in the Mediterranean diet, and several typical Spanish and Portuguese varieties could potentially be used as such. In order to ensure a good‐quality product, the effect of different factors such as elaboration processes, irrigation conditions, crop year and their crossover interaction on acrylamide content and antioxidant compounds needs to be deeply studied. RESULTS: When looking through irrigation, regulated deficit irrigation (RDI) presented lower acrylamide levels than rainfed conditions for 'Cordovil de Elvas', 'Picual' and 'Verdeal Alentejana'. No significant interactions were found between the type of irrigation and elaboration style for 'Arbequina' and 'Koroneiki' varieties. Although RDI had the largest concentration of total phenols, antioxidant activity was also the highest. The table olives harvested in the crop year of 2019 showed lower levels of acrylamide due to a significant relationship between the crop year and irrigation conditions. CONCLUSIONS: Novel varieties to be marketed should be taken into consideration for table olive elaboration. The impact of the crop year on the bioactive value of table olives and crossover interactions relies strongly in climatological conditions. Last but not least, the benefit of selecting the best irrigation and elaboration methods is crucial to ensure desirable acrylamide levels. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: Properly reduced irrigation combined with nitrogen (N) application can be used to improve crop water use efficiency (WUE) in arid regions, but its effect on sugar beet is unknown at present. A two‐year field experiment was conducted to evaluate the effects of N application (N0, 0; N1, 150; N2, 225 kg N ha−1) on the canopy production capacity (CPC), yield and WUE of sugar beet under normal irrigation (W1, 70% of field capacity (FC)) and deficit irrigation (DI) (W2, 50% FC) in the early growth stage (EGS). Results: The results showed that the W2 treatment reduced the CPC by reducing gas exchange, leaf area index (LAI) and chlorophyll content (SPAD value) of sugar beet leaves compared to the W1 treatment. However, DI combined with N application increased these parameters. Specifically, N application increased the net photosynthetic rate by 40.7% by increased gas exchange, SPAD and LAI compared to the N0 treatment. In addition, N application increased WUE by 12.5% by increasing thickness of upper surface, stomatal aperture and cross‐sectional area of petiole. This ultimately led to a significant increase in taproot yield (TY; 19.7%) and sugar yield (SY; 57.6%). Although the TY of the N2 treatment was higher than that of the N1 treatment, the SY and WUE did not increase significantly and the harvest index decreased significantly by 9.3%. Conclusion: DI combined with 150 kg N ha−1in the EGS of sugar beet increases the WUE in arid areas while avoiding yield loss by improving the CPC. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In the ecological protection zone, it is unclear how the joint development of urban agglomeration affects the supply–demand of water‐related ecosystem services (ESs). This study took northwest Hubei, China (Exibei), a national ecological function area, as a case study and predicted the land‐cover distribution in 2040 under three scenarios: natural scenario (2040NS), economic development (2040ED) and ecological protection (2040EP). And the supply–demand risks of water‐related ESs were simulated under three scenarios. Results indicated that (1) the increase in forest land (0.70%) under 2040NS, construction land (50.03%) under 2040ED and water body (15.16%) under 2040EP basically happened through the occupation of cultivated land; (2) under three scenarios, although the water yield demand in 2040 increased significantly, the supply still fully meet demand; (3) from 2020 to 2040, more than 13.50% of the areas in Exibei of water yield changed from surplus to deficit, mainly covering the north Xiangyang City and the middle Shiyan City; and (4) the change in supply and demand of soil retention from 2020 to 2040 was not obvious. This study provides assistance in water resources rational allocation in ecological function zones with rapid economic development and urban expansion. [ABSTRACT FROM AUTHOR]

Irrigated cropland continues to increase in Tennessee to sustain yield when seasonal temperatures are high and water deficit occurs. Corn (Zea mays L.) production is directly related to water availability. Inefficient irrigation scheduling can result in excessive or inadequate water applications. The objective of this study was to optimize profitable corn yield using soil water sensors to improve irrigation scheduling. Three irrigation regimes plus a rainfed/check were evaluated in a field study at the University of Tennessee Milan Research and Education Center in 2020 and 2021. Soil water level was monitored with Meter Inc. Teros 21 matric potential sensors and ZL6 soil‐water loggers. Irrigation‐scheduling decisions were based on rainfall, plant growth stages, and soil water sensors. An optimal irrigation schedule was determined within this study that increased yield by 13.0% and 3.0%, respectively, in 2020 and 2021 while also having the lowest cost among irrigation treatments. Results indicate that irrigation scheduling can improve yield, conserve water, and increase economic returns. Core Ideas: Using smart irrigation in humid regions can conserve water without affecting yield.Utilizing soil water sensors as a tool to monitor crop water needs can improve irrigation scheduling.By studying a range of irrigation regimes, the level of deficit irrigation that optimizes yield and net return can be determined. [ABSTRACT FROM AUTHOR]

Summary: Accounting for water limitation is key to determining vegetation sensitivity to drought. Quantifying water limitation effects on evapotranspiration (ET) is challenged by the heterogeneity of vegetation types, climate zones and vertically along the rooting zone.Here, we train deep neural networks using flux measurements to study ET responses to progressing drought conditions. We determine a water stress factor (fET) that isolates ET reductions from effects of atmospheric aridity and other covarying drivers. We regress fET against the cumulative water deficit, which reveals the control of whole‐column moisture availability.We find a variety of ET responses to water stress. Responses range from rapid declines of fET to 10% of its water‐unlimited rate at several savannah and grassland sites, to mild fET reductions in most forests, despite substantial water deficits. Most sensitive responses are found at the most arid and warm sites.A combination of regulation of stomatal and hydraulic conductance and access to belowground water reservoirs, whether in groundwater or deep soil moisture, could explain the different behaviors observed across sites. This variety of responses is not captured by a standard land surface model, likely reflecting simplifications in its representation of belowground water storage. [ABSTRACT FROM AUTHOR]

The pasture legume Trifolium subterraneum ssp. yanninicum L. is waterlogging tolerant, but water‐deficit (WD) susceptible. The interactive effect of waterlogged (WL) and WD (soil moisture fluctuation [SMF]) results in a severe stress impact. We studied three diverse ecotypes to identify traits associated with adaptation to SMF. Ecotypes were established in a glasshouse with two treatments imposed at 21 days: well‐watered (WW–WW; 80% field capacity [FC]) and WL to WD (WL–WD). For WL–WD, pots were WL for 28 days (Harvest I), and then transitioned to WD (drained to 40% FC) and maintained for 10 days (Harvest II). For shoot relative growth rates (RGR) at Harvest I, WL had relatively little impact, although there was a greater reduction for Ecotype A (80% of WW) than Ecotypes B (92%) and C (87%). However, between Harvests I and II, the impact of WL–WD varied among ecotypes with Ecotype A being less affected (75% of WW–WW) than Ecotypes B (57%) and C (63%). For root RGR at Harvest I, WL resulted in a greater reduction for Ecotype A (52% of WW) than Ecotypes B (77%) and C (74%), while for WL–WD between Harvests I and II, Ecotype A showed a large increase (117% of WW–WW) compared to Ecotypes B (95%) and C (87%). In conclusion, the response to WD following WL varied among ecotypes, which demonstrates contrasting adaptation responses to SMF unrelated to WL tolerance. High yield under WL together with capacity for rapid growth post‐WL in a drying soil profile could enhance adaptation to SMF. [ABSTRACT FROM AUTHOR]

Background: Water stress during the growing season of the almond tree is the factor that most limits its yield. Different strategies have been studied in recent years to reduce its negative effects, such as deficit irrigation and the application of reflective spray compounds. A 3‐year experiment (2019–2021) was set in a factorial design in which the effect of regulated deficit irrigation and foliar kaolin spray was evaluated on morphological characteristics (weight, length, width, and thickness of the nut and kernel, shell thickness, kernel yield, double kernels, and damaged kernels), color properties, nutritional value (carbohydrates, fat, proteins and ash) and chemical parameters (free sugars and fatty acids profiles). Results: In general, the significant differences between the treatments did not have a similar trend in the 3 years of the study. Regulated deficit irrigation and kaolin had no detrimental impact on almond morphological and color characteristics. The almond free sugars concentration was relatively stable under deficit irrigation and kaolin application. On the other hand, kaolin application positively affected the synthesis of linoleic acid. Conclusion: Reducing the amount of irrigation water applied to almonds contributes to the sustainability of production without negatively affecting quality and even improving some quality parameters. In general, the foliar application of kaolin did not show significant differences in the evaluated morphological parameters. However, in terms of chemical composition, kaolin led to an increase in the concentration of linoleic acid and sucrose. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study examines the effects of three irrigation regimes with a combination of saline water and treated wastewater on the accumulation of heavy metals in barley grains. A field experiment was designed as a split‐split plot arrangement in a randomized complete block design, in which treatments were different irrigation regimes (50%, 70%, and 100% full irrigation) and irrigation water types (saline water [SW], treated wastewater [TW], mixed water resources [MWR], and alternative irrigation [AI]). After cultivation and harvesting of the barley crop, the grain yield, 1000‐grain weight, and contents of heavy metals in the grains were measured. The grain yield was enhanced by TW alone, MWR, and AI to 12.8%, 5%, and 9.5% under 70%‐deficit irrigation; and 58.3%, 21.7%, and 8.7% under full irrigation, respectively. Based on the guidelines for safe limits of heavy metals in edible plants and livestock feed, the barley grains were safe for livestock and toxic for humans. The trend of heavy metal contents in the grains was Fe > Zn > Pb > Cu ≥ Cr > Cd. Irrigation with SW compared with TW increased Fe, Cu, Zn, Pb, Cd, and Cr contents in the grains to 11.75%, 10.97%, 5.22%, 19.15%, 3.45%, and 9.21%, respectively. The amounts of toxic elements of Cd and Pb were maximized by using MWR, whereas the Cr content in the grain was maximized by using AI. There were no significant difference in the metal uptake by the grains among all irrigation regimes in any irrigation water resource. However, compared with the other irrigation regimes, the full irrigation resulted in lower Zn, Cu, and Cd contents, whereas the 50%‐deficit irrigation led to lower Pb and Cr contents in the grains. Therefore, irrigation with TW is recommended based on the grain yield, whereas AI is suggested due to lower Cu, Pb, and Cd contents in the grain, and MWR is recommended due to lower Cr content. Furthermore, full and 50%‐deficit irrigation regimes are recommended to, respectively, maximize grain yield and minimize the toxic metal contents in the grain. Practitioner Points: Mixed saline water and treated wastewater and alternative irrigation enhanced grain yield.Saline water versus treated wastewater increased the grain heavy metal contents.Alternative irrigation decreased Fe, Cu, Pb, and Cd amounts in the grain.Grain Cu content had strong relationship with irrigation regime.50%‐deficit irrigation minimized Pb and Cr contents in the grain. [ABSTRACT FROM AUTHOR]

Soil and groundwater salinity associated with limited rainfall are the challenges for checking salinity build‐up in semi‐arid regions. This field experiment was conducted to test the impact of deficit saline irrigation (DSI) (in winter) with mulching and tillage on salinity build‐up, yield and nutritive value of rainfed‐forage sorghum. Tillage (reduced, conventional and zero), saline water (8.0 dS m−1) irrigation (100%, 80% and 60% of water requirement [WR] in wheat) and mulch were allocated following split factorial layout. DSI with mulching produced at par wheat and sorghum yield compared with 100WR irrigation with harvested rainwater. Mulching improved wheat grain yield and the soil water content by ~13% throughout the cropping season. Forage sorghum yield was increased by DSI and mulching in the previous season compared with irrigation with 100WR saline water. Reduced tillage declined the neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL) with an increase in cell soluble constituents. DSI and mulching also increased the digestible nutrient, crude protein (CP), ash and reduced ADF of sorghum. Soil salinity showed a negative correlation with CP, positive correlation with ADF, ADL and cellulose. Therefore, it is recommended that DSI and reduced tillage with mulching can be a reliable option for productive use of saline soils and water by cropping system intensification. These results also showed the potential for achieving 2030 agenda for sustainable development goals as well as targets of land degradation neutrality in salt‐affected soils by savings irrigation, doubling cropping intensity and preventing salinity build‐up. [ABSTRACT FROM AUTHOR]

Copyright of World Water Policy is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Freezing is a good method of preserving the sensory and nutritional quality of fresh fruits and vegetables. However, big ice crystals always form in a common freezing process which causes mechanical damage to the fruit and vegetable cells and results in low-quality products. The external magnetic field can interfere with the state of the internal water, thus changing the ice crystal formation process accordingly. It was suggested that suitable magnetic field treatments can affect the biological characteristics of fruits and vegetables and improve the quality of the frozen products. In this experiment, Korla fragrant pear was freezing processed at the different static magnetic field (SMF) strengths (0, 2, 4, 6, 8, and 10 mT), and the pear quality was evaluated by juice loss, color, texture, total soluble solid content and total acid content, water state, and distribution. The results showed that the utilization of SMF in freezing reduced the loss of juice and soluble solids, and maintained the titratable acidity. However, SMFs performed poorly in color and texture protection. This research suggested that magnetic field-assisted freezing had some positive effects on the quality of frozen Korla fragrant pear, but more works need to be done to further improve the product quality. [ABSTRACT FROM AUTHOR]

Climate change is expected to increase the strength of ocean Oxygen Deficient Zones (ODZs), but we lack a detailed understanding of the temporal or spatial variability of these ODZs. A 50‐year time series in the Eastern Tropical North Pacific (ETNP) ODZ revealed that it has strengthened by 30% from 1994 to 2019. We subdivided the ODZ into a core and a deep layer based on potential density and revealed that different processes control the magnitude of fixed nitrogen loss between these regions. We postulate that the depth of the upper ETNP ODZ water mass, the 13°C Water, influences the organic carbon supply to the core ODZ and therefore its strength. We correlated the maximum fixed nitrogen loss in the core ODZ with a nearby sedimentary nitrogen isotope record and found that this recent increase in the magnitude of fixed nitrogen loss occurred only a few times over the last 1,200 years. Using this correlation, we derived the first confidence interval for the natural variability of the maximum fixed nitrogen loss within the ETNP ODZ, which has a range of 3.3 μmol kg−1 (p = 0.01). While the current increase is only comparable to two previous events, it is within the confidence interval for natural variability (p = 0.03). The deep ODZ also strengthened from 2016 to 2019 by approximately 30%, but this increase occurred more rapidly than the core ODZ, and this dramatic increase was not observed over the rest of the 40 years. Climate‐driven intensification could lead to unprecedented changes in the ETNP ODZ within the next decade. Plain Language Summary: Naturally occurring ocean Oxygen Deficient Zones (ODZs) play a significant role in regulating ocean nutrient availability and ecosystem structure. Climate change is expected to strengthen these ODZs. A 50‐year time series in the world's largest ODZ revealed that it has strengthened by 30% from 1994 to 2019. Based on sedimentary records, this rapid increase has only occurred twice over the last 1,200 years. Although this sedimentary record suggests there is high but not extremely certain likelihood that climate change caused this recent intensification, continued strengthening at these rates could lead to unprecedented changes within the next decade. Key Points: The nitrogen deficit in the largest Oxygen Deficient Zone (ODZ) has increased over 50 years, indicating a 30% increase in ODZ strengthThe maximum fixed N loss of the core ODZ (σθ 26.2–26.8 kg m−3) is significantly different (p = 0.03) from its natural variabilityThough the core ODZ intensification is significant, we cannot yet claim with virtual certainty (p = 0.01) that climate change caused it [ABSTRACT FROM AUTHOR]

SUMMARY: Most studies assume midday gas exchange measurements capture the leaf's daytime performance. However, stomatal conductance (gs) and photosynthesis (An) fluctuate diurnally due to endogenous and environmental rhythms, which can affect intrinsic water use efficiency (iWUE). Six Sorghum lines with contrasting stomatal anatomical traits were grown in environmentally controlled conditions, and leaf gas exchange was measured three times a day. Stomatal anatomy and kinetic responses to light transients were also measured. The highest An and gs and the lowest iWUE were observed at midday for most lines. Diurnally averaged iWUE correlated positively with morning and midday iWUE and negatively with the time taken for stomata to close after transition to low light intensity (kclose). There was significant variation among sorghum lines for kclose, and smaller kclose correlated with lower gs and higher stomatal density (SD) across the lines. In turn, gs was negatively correlated with SD and regulated by the operational stomatal aperture regardless of stomatal size. Altogether, our data suggest a common physiology to improve iWUE in sorghum related to the control of water loss without impacting photosynthesis relying on higher SD, lower stomatal aperture and faster stomatal closing in response to low light intensity. Significance Statement: Sorghum lines that maintain high diurnal water use efficiency had higher stomatal density and exhibit faster stomatal closure rather than faster stomatal opening, which aligns with a strategy favouring water conservation over maximising photosynthesis. [ABSTRACT FROM AUTHOR]

Based on the experimental data of regulated deficit irrigation at different growth stages on field pear‐jujube tree (Zizyphus jujube Mill.) during 2005–2007 in Northwest China, the regulated deficit irrigation integrated benefits (RDIIB) with different water deficit treatments at different growth stages were evaluated and classified using a model. The results in 2005–2006 showed that the RDIIB under single‐stage water deficit at fruit maturity stage were better than the other treatments, and the best RDIIB were gained under moderate (IVSD) or severe deficit (IVMD) at fruit maturity stage. The results in 2006–2007 also indicated that the four double‐stage water deficit schemes have the better RDIIB, and the best scheme was severe water deficit at bud burst to leafing stage plus moderate water deficit at fruit maturity stage. The RDIIB evaluation model based on information entropy method provided the reliable technical guidance for the optimal RDI scheme of pear‐jujube tree. [ABSTRACT FROM AUTHOR]

Understanding the nexus between food, energy, and water systems (FEW) is critical for basins with intensive agricultural water use as they face significant challenges under changing climate and regional development. We investigate the food, energy, and water nexus through a regional hydroeconomic optimization (RHEO) modeling framework. The crop production in RHEO is estimated through a hierarchical regression model developed using a biophysical model, AquaCropOS, forced with daily climatic inputs. Incorporating the hierarchical model within the RHEO also reduces the computation time by enabling parallel programming within the AquaCropOS and facilitates mixed irrigation—rainfed, fully irrigated and deficit irrigation—strategies. To demonstrate the RHEO framework, we considered a groundwater‐dominated basin, South Flint River Basin, Georgia, for developing mixed irrigation strategies over 31 years. Our analyses show that optimal deficit irrigation is economically better than full irrigation, which increases the groundwater pumping cost. Thus, considering deficit irrigation in a groundwater‐dominated basin reduces the water, carbon, and energy footprints, thereby reducing FEW vulnerability. The RHEO also could be employed for analyzing FEW nexus under potential climate change and future regional development scenarios. Key Points: A new regional hydroeconomic optimization modeling framework is proposed for mixed irrigation regimes using AquaCropOSOptimal deficit irrigation strategy is economically better than full irrigation by reducing the cost and energy for groundwater pumpingCrop simulation module and optimization module are linked using Bayesian Hierarchical Model to reduce computation time [ABSTRACT FROM AUTHOR]

Spectral indices can be used as fast and non‐destructive indicators of plant water status or stress. It is the objective of the present study to evaluate the feasibility of using several spectral indices including water index (WI) and normalized spectral water indices 1–5 (NWI 1–5) to estimate water status in olive trees in arid regions in Iran. The experimental treatments involved two olive cultivars (Koroneiki and T2) and four irrigation regimes (irrigated with 100%, 85%, 70%, and 55% estimated crop evapotranspiration [ETc]). The results obtained showed that olive trees subjected to the different irrigation regimes of 85%, 70%, and 55% ETc experienced soil water content (SWC) deficits by 4.5%, 12%, and 20.5% that of the control, respectively. Significant differences were observed among the treatments with respect to measured relative water content (RWC), SWC, and the spectral indices of WI and NWI 1–5. The normalized spectral indices combining NIR and NIR wavelengths were found more effective in tracking changes in RWC and SWC than those that combine NIR and VIS or VIS and VIS wavelengths, respectively. Spectral indices were closely and significantly associated with RWC (.63**

The partitioning of terrestrial precipitation into evapotranspiration and river flow shapes ecosystems and water resources. Using observed precipitation, discharge, and satellite‐derived soil moisture and vegetation indices for watersheds located throughout the contiguous United States, we demonstrate that ecosystems maximize long‐term average evapotranspiration when plants transpire older water (i.e., longer time since precipitation or snowmelt). However, ecosystems that transpire older water do so at the expense of decreased drought resilience and maintain higher stem water resilience than those that use younger water, suggesting a growth versus drought resilience tradeoff that is well predicted by water age. These findings indicate that the role of water age integrates processes whereby the relevance of age extends beyond its previously studied effects on biochemical and transport processes, as we reveal it shapes long‐term terrestrial evaporation rates and ecosystem plant functioning under drought stress. Plain Language Summary: Most terrestrial precipitation does not end up in streams but returns to the atmosphere as evapotranspiration (ET). What controls long‐term ET rates and dictates the effects of drought on transpiration and vegetation dynamics remains hard to generalize. Here we link the concept of ET water age to these variables to show that ecosystems that transpire older water have higher ET rates but do so at the expense of decreased drought resilience than those that use younger water. This indicates that water age is critical to the terrestrial water balance and plant functioning. Key Points: We modeled evapotranspiration (ET) water ages for 472 watersheds across contiguous United StatesOlder ET water ages are associated with ET rates closer to the upper physical limit, but lower vegetation resilienceET water ages explain tradeoffs between long‐term evapotranspiration and ecosystem drought resilience [ABSTRACT FROM AUTHOR]

SWIB - An Online Model to Estimate Daily Crop Water Stress, Irrigation Needs, and Soil Water Budget The amount of water stored in the soil is the resultant of the interdependence of soil, climate, and biota, with ecosystems that are under significant human impact being subjected to additional controlling factors. SWIB calculates the number of days when irrigation is required, the crop irrigation requirement and by considering the losses to ET and return flow, the irrigation water supply requirement. [Extracted from the article]

A resurgence of dam planning and construction is under way in river basins where untapped hydropower potential could meet growing energy demands. Despite calls for more comprehensive evaluation of dam projects, most dams continue to be planned with traditional methods that neglect interdependencies between planning and management and cumulative impacts of multiple new dams. Using the transboundary Zambezi Watercourse as a case study where competing demands for water, energy, and food are increasing, we contribute to a novel dam planning approach that integrates sequencing of planned reservoirs with adaptive operations. While additional hydropower capacity reduces structural energy deficits, operating polices emerge as the main driver of human‐environmental tradeoffs, so much so that single‐objective operating policy selection may lead to erroneous perceptions of tradeoffs across infrastructure options. Furthermore, compared to an operation and sequencing strategy that singularly maximizes hydropower, seeking compromise through operations while constructing dams early improves environmental and irrigation objectives by 50% and 80% with an 8% loss in hydropower. Alternatively, seeking compromise only through delayed dam construction yields modest environmental and irrigation improvements of 6% and 9%, respectively, with a 22% loss in hydropower. The robustness of this result is tested under an ensemble of stochastic streamflow where environmental flow and irrigation deficits are found more sensitive to operations than shifts in water availability. The predominance of operating policies is relevant for improving multi‐objective dam planning in other river basins already fragmented by dams built in the twentieth century. Key Points: A two‐part multi‐objective framework is presented that jointly optimizes the sequencing and operations of multipurpose reservoirsOne or two existing reservoirs in a river basin may dominate human‐environmental tradeoffs with implications for planning new damsReservoir operating policies eclipse reservoir network configurations and sequencing in balancing conflicting objectives [ABSTRACT FROM AUTHOR]

Copyright of Irrigation & Drainage is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Perennial ryegrass (Lolium perenne L.) is a major turfgrass species in temperate regions around the world. Unfortunately, it lacks drought tolerance compared with other cool‐season turfgrass species and often requires substantial inputs of freshwater as supplemental irrigation to achieve high turfgrass quality. To address the need for more drought‐tolerant perennial ryegrass, we conducted an evaluation of perennial ryegrass germplasm from the U.S. National Plant Germplasm System under deficit irrigation conditions and two mowing heights at Kaysville and Logan, UT during 2017 and 2018. We characterized turfgrass dark green color, ground cover, density, and quality using digital photography to capture images that we then converted to trait values using the TurfAnalyzer software. The higher mowing height resulted in greater ground cover, density, and quality. The collection of 49 germplasm accessions and 11 cultivars exhibited substantial variation for turfgrass dark green color, ground cover, density, and quality. Cultivars included as checks generally had greater turfgrass color and density, but the germplasm accessions generally had greater turfgrass ground cover and quality. Selection among these germplasm accessions will provide elite germplasm with utility for improving these traits in applied perennial ryegrass turfgrass breeding programs. Core Ideas: Higher mowing height resulted in greater perennial ryegrass ground cover, density, and quality. Population variation significantly differed from zero for dark green color, ground cover, density, and quality. Four Romanian accessions, one Norwegian accession, and one Russian accession possess great potential. [ABSTRACT FROM AUTHOR]

With an objective to develop a closed loop wastewater biorefinery, the performance of two free floating aquatic weeds water hyacinth (Eichhornia crassipes, Mart, Solms) and salvinia (Salvinia molesta, Mitchell) is explored when either is used as the main bioagent for treating sewage in "sheet flow root level" (SHEFROL) bioreactors. Both the macrophytes prove to be easy to propagate and maintain while they are able to help in achieving significant primary, secondary, and tertiary treatment steps of greywater in a single step. Water hyacinth is able to remove suspended solids, chemical oxygen demand (COD), biological oxygen demand (BOD), total Kjeldahl nitrogen, soluble phosphorous, zinc, copper, nickel, and manganese to the average extents of 81%, 79%, 43%, 41%, 40%, 36%, 34%, and 29%, respectively. The reduction in COD and BOD levels achieved by salvinia is marginally lesser than by water hyacinth but in terms of the removal of other pollutants, the performance of salvinia is comparable to that of water hyacinth. It is possible to convert the dead or harvested plants to organic fertilizer thus making it a closed‐loop system with no waste of its own. [ABSTRACT FROM AUTHOR]

Deficit irrigation (DI) is an effective way to save irrigation water while maintaining sustainable yield in irrigated crops. However, limited information is available related to canopy structure and solar radiation use under DI condition. In this study, our objective was to assess maize hybrids for leaf development, photosynthetically active radiation (PAR) interception and water use under DI condition. Field experiments were conducted in 2016 and 2017 in four maize hybrids at well‐watered (I100, referring to 100% evapotranspiration [ET] requirement) and DI (I75, referring to 75% ET requirement) water regimes. Compared to I100, I75 did not reduce maize biomass and grain yield. Although DI reduced the leaf appearance rates (1.5% in 2016 and 7.6% in 2017) and resulted in greater variations in leaf area index (LAI) among hybrids, the amount of PAR interception was not affected during the growing season. DI significantly reduced the seasonal ET in both years (19.8% in 2016 and 26.6% in 2017). All the hybrids extracted more soil water (29 mm in 2016 and 27 mm in 2017) at I75 than at I100. Maize plants at I75 had greater water use efficiency (WUE) (1.68 kg m−3) than those at I100 (1.41 kg m−3). However, DI did not affect radiation use efficiency (RUE). In conclusion, DI at I75 maintained grain yield through improved soil water extraction and WUE but stable canopy radiation interception and RUE. [ABSTRACT FROM AUTHOR]

Several new bermudagrass cultivars are available and commonly used on golf course fairways. However, little is known about their cultural requirements or how these cultivars perform under lower inputs regimes. A 2‐year study was conducted at University of Florida, Fort Lauderdale Research and Education Center, to assess performance of four hybrid bermudagrass [Cynodon dactylon L. Pers. X Cynodon transvaalensis (Burtt‐Davy)] cultivars ('Latitude 36', 'Tifway 419', 'TifGrand' and 'TifTuf'), and 2 common bermudagrass (Cynodon dactylon L. Pers.) cultivars ('Bimini' and 'Celebration') irrigated at either 50% or 80% reference evapotranspiration (ETo) and fertilised at either 0, 146, 244, or 342 kg N ha−1 year−1. Plots were evaluated monthly for turfgrass quality, dark green colour index (DGCI), normalised difference vegetation index (NDVI), and Chlorophyll Index, and seasonally for N tissue content. Plots watered at 80% ETo enhanced bermudagrass quality compared to 50% ETo, DGCI and NDVI only in two months out of 24. Latitude 36 and Celebration were the top‐rated cultivars, and their quality was not affected by no N fertilisation. Conversely, TifGrand, TifTuf and Tifway that received no N fertilisation resulted in insufficient quality during the second year of the study. Insufficient quality may be linked to reduced N metabolization compared to the highest rated cultivars. Results show that new cultivars such as Latitude 36 and Bimini could be maintained at sufficient quality levels with reduced water and N inputs in South Florida. [ABSTRACT FROM AUTHOR]

Background: The increasing concentration of atmospheric CO2 not only affects the growing environment of crops but also aggravates the global greenhouse effect and further aggravates the problem of water shortage. The combined effect of water deficit and potassium (K) application has not been widely studied. Aims: A pot experiment was conducted to investigate the effect of deficit irrigation (DI) and K application at different growth stages on carbon allocation and enzyme activities related to sugar metabolism. Methods: Tomatoes were transplanted and planted on April 26, 2017 and harvested on August 15, 2017. Four irrigation regimes were implemented with two water levels (full irrigation‐W and DI‐W/2) in different growth stages, and each water treatment was equally divided into two subgroups: with K (K1) and without K (K0). Fruits from the first to fourth trusses of the tomato plants were sampled. Tomato growth, carbon allocation, and related enzyme activities were measured. Results: The fresh weight (FW), dry weight, and relative growth rate of dry mass were sensitive to irrigation amount under K fertilization, enhancing the promotion effect of irrigation on fruit. Meanwhile, carbon allocation was sensitive to irrigation amount under K regime. Sucrose synthase (SuSy), acid invertase (AI), and sucrose phosphate synthase (SPS) were also highly sensitive to irrigation amount under K application condition. Starch phosphorylase displayed a quadratic parabola for irrigation amount, and adenosine diphosphate glucose pyrophosphorylase (AGPase) was highly sensitive to irrigation amount without K fertilization. Carbon in the form of other carbohydrates, carbon in the form of soluble sugar (Csol), and fruit water content were the factors that had the greatest influence on the principal components. Classification by K‐means algorithm and canonical correlation analysis showed that FW, fructose, sucrose, and starch could be used as significant indicators of the dry matter components of the fruit for the treatment without K. In the case of K regime, SuSy, AGPase, AI, and Csol could be used as a significant indicator of the correlation analysis of carbon metabolism activity. Conclusions: The factors related to the improvement of fruit quality and carbon allocation by deficient irrigation and K application were explored. Water stress changed the distribution of photosynthetic carbon between starch and soluble sugar. K application further changed the balance between soluble sugars and other compounds. In particular, it significantly increased the carbon content of soluble sugars and decreased that of other compounds. AI and SuSy are key enzymes affecting carbon metabolism under water‐deficient conditions. [ABSTRACT FROM AUTHOR]