Area under vegetable cultivation is expanding in arid and semi-arid regions of the world to meet the nutritional requirements of an ever-growing population. However, water scarcity in these areas is limiting vegetable productivity. New water-conserving irrigation management practices are being implemented in these areas. Under these irrigation management practices, crops are frequently exposed to some extent of water stress. Vegetables are highly sensitive to water stress. For the successful implementation of new irrigation practices in vegetable crops, it is of immense importance to determine the threshold water deficit level which will not have a detrimental effect on plant growth and yield. Along with this, plant response and adaptation mechanisms to new irrigation practices need to be understood for the successful implementation of new irrigation practices. To understand this, water stress indicators that are highly responsive to water stress; and that can help in early detection of water stress need to be identified for vegetable crops. Plant-based water stress indicators are quite effective in determining the water stress level in plants because they take into account the cumulative effect of water stress due to declining soil moisture status and increased evaporative demand of the atmosphere while determining the water stress level in plant. Water stress quantification using plant-based approaches involves direct measurements of several aspects of plant water status and indirect measurements of plant processes which are highly sensitive to water deficit. In this article, a number of plant-based water stress indicators were critically reviewed for (1) their efficacy to determine the level of water stress, (2) their potential to predict the yield of a crop as affected by different water-deficit levels and (3) their suitability for irrigation scheduling in vegetable crops.

Th e importance of saffl ower (Carthamus tinctorius L.) is increasing as a low input, stress-tolerant oilseed crop around the world. Adapting a crop growth model for saffl ower will help to assess the feasibility of this crop under diverse environmental conditions with relatively limited fi eld experimentation. Th e objective of the project was to adapt the Decision Support System for Agrotechnology Transfer (DSSAT) Cropping System Model (CSM-CROPGRO) to simulate growth and seed yield of spring saffl ower. Th e CROPGRO template approach was used, and parameters in species and cultivar fi les were developed based on saffl ower literature and calibration to fi eld data. Th e entered base temperatures for photosynthetic, vegetative, and reproductive processes of saffl ower ranged from 0 to 5°C while corresponding optimum temperatures varied from 19 to 40°C. Simulated results were compared with observed data collected from fi eld experiments conducted at Clovis, NM, during 2013 and 2014. Th e model predicted the crop life cycle (anthesis and harvest maturity date) with relative root mean square error (RRMSE) of 0.07. Average plant biomass, head mass, head number and seed number were satisfactorily simulated when compared to observed values. Seed yield, averaged over irrigation treatments and years, was predicted as 1963 kg ha -1 compared to measured value of 1902 kg ha -1 with RRMSE of 0.12. Reasonable prediction of phenology, growth, and yield by the model adapted for saffl ower suggested that the CROPGRO-saffl ower model is promising to simulate saffl ower production in semiarid climates. However, further testing of the CROPGROsaffl ower model under diff erent environments is needed.

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Salinity stress is among the major abiotic stresses prevailing in arid and semiarid areas such as the southern high plains of the United States. In these areas, both declining quality of groundwater and cultivation practices have resulted in increased accumulation of salts in the root zone. The occurrence of excessive salts in the root zone is detrimental for plant growth and economic yield. Recently, biochar has received a great consideration as a soil amendment to mitigate the detrimental impacts of salinity stress. However, the effectiveness of biochar to mitigate the salinity stress depends on the feedstock type, pyrolysis temperature and time, soil type and properties, and plant species. Therefore, a pot experiment in a greenhouse was conducted to 1) examine the effects of salinity stress on physiology, shoot and root growth, and yield of eggplant (Solanum melongena L.), and 2) evaluate the potential of hardwood biochar and softwood biochar to mitigate the damaging effects of salinity stress on eggplant. The experiment was conducted in a split-plot design with three salinity levels of irrigation water [S0 (control, 0.04 dS·m−1), S1 (2 dS·m−1), and S2 (4 dS·m−1)] as main-plot factor and three biochar treatments [B0 (control, non-biochar), Bh (hardwood biochar), and Bs (softwood biochar)] as subplot factor with four replications. Results showed that stomatal conductance (gS) and photosynthesis rate decreased significantly, while leaf temperature and electrolyte leakage increased significantly with increase in irrigation water salinity levels. Root growth (root length density and root surface area density), shoot growth (plant height, stem diameter, and leaf area), and yield of eggplant declined with increase in levels of salinity stress. Biochar application helped to enhance gS and photosynthesis rate, and to decrease leaf temperature and electrolyte leakage in leaf tissues of plants. This resulted in better root growth, shoot growth, and fruit yield of eggplant in treatments amended with biochar than non-biochar (control) treatment. There was no significant difference in the effect of two types of biochars (hardwood and softwood biochar) on physiology, root growth, shoot growth, and yield of eggplant. Therefore, it can be concluded that softwood and hardwood biochars could be used to minimize the detrimental impacts of salinity stress in eggplant.

Water stress is the most important environmental factor limiting crop yield in the southern High Plains. Drought tolerant crops along with deficit irrigation strategies may be promising for sustainable agriculture in the region. The objective of this study was to assess water relations, photosynthesis, yield‐forming components, and yield of spring safflower (Carthamus tinctorius L.) cultivars under growth stage based irrigation management. A blocked split plot design was used with irrigation treatments (fully irrigated [FI], stress at vegetative stage [VS], stress at reproductive stage [RS], and dryland [DL]) as the main plot and cultivars (PI8311, 99OL and Nutrisaff) as subplot in four replications. Measurements of water potential (Ψl) indicated that irrigation treatments imposed water stress on safflower. Safflower responded to stress by regulating stomata and osmotic adjustment. Water stress significantly reduced photosynthesis (Pn), leaf area index (LAI) and light interception in all stress treatments, resulting in decreased biomass accumulation. Seed yield of safflower was strongly related to biomass production (R2 = 0.61). Among yield‐forming traits, heads per plant were more influential in yield formation than seeds per head and 1000‐seed weight. Compared to the FI treatment, RS treatment reduced seed yield by 19 and 20% in 2013 and 2014, respectively; while the same reduction in VS treatment was 25 and 22%, respectively. However, seed yield differences between RS and VS treatments were not statistically significant.

Core Ideas• Declining groundwater supplies, the increasing cost of irrigation, and excessive summer dryness threaten the sustainability of corn production in the Texas High Plains (THP).• Forage sorghum and pearl millet are potential alternatives to corn silage.• Sorghum and pearl millet are likely to replace much of the corn silage crop in the THP. AbstractDiminishing irrigation water from the Ogallala aquifer to produce forage crops is jeopardizing the beef and dairy industries in the Texas High Plains (THP). The principal feed ingredient of the beef and dairy sectors is corn (Zea mays L.) silage, which is produced near the feeding operations to minimize transport costs, unlike concentrated feed, which can be transported long distances. The declining pumping capacity of irrigation wells hinders the ability to sustain a supply of water for profitable corn production in the THP. Forage sorghum [Sorghum bicolor (L.) Moench] and pearl millet [Pennisetum glaucum (L.) R. Br.] are known for their ability to tolerate drought and heat, which enables them to produce high forage yields with less water than corn. Pearl millet and sorghum can also be harvested as hay, greenchop, or silage like corn. Introduction of the brown midrib (BMR) trait into pearl millet and sorghum has enhanced their nutrient composition. Brown midrib is a genetic trait associated with reduced lignin synthesis, resulting in enhanced digestion of forage fiber in the bovine (Bos taurus) rumen, thereby increasing weight gain and milk production per ton of forage fed over non-BMR types. Therefore, BMR forage sorghum and BMR pearl millet could be potential alternative forage crops where water is insufficient to grow corn silage in the THP. Hence, the objective of this review paper is to compare the water use efficiency, nutritional composition, associated antinutritional compounds, animal performance, and potential yields of BMR forage sorghum and BMR pearl millet with corn.

Water shortage is one of the major challenges faced by the current agricultural systems worldwide, especially in arid and semi-arid regions. Deficit irrigation (DI), a water-saving strategy of applying less water than crop evapotranspiration (ETc) demands, has been extensively investigated in different crops, including water-intensive vegetables. The DI strategies such as regulated deficit irrigation (RDI) and partial root zone drying (PRD) generally increase water use efficiency (WUE) and have emerged as potential practices to save water for agricultural sustainability. However, in view of the sensitivity of shallow-rooted vegetable crops to water stress, DI is often associated with yield losses. A review of 134 DI reports of vegetable crops revealed significant reductions in yield under all DI levels in 52% of cases and yields statistically similar to those of full irrigation (100% ETc in most cases) under small water deficits in 44% of cases, thereby raising concerns about the sustainability of vegetable production under DI. Biochar, a carbon-rich co-product of pyrolysis of organic matter, is increasingly undergoing study as a soil amendment to mitigate drought stress and is being explored as an additional practice with DI to minimize the yield losses due to water deficits. This work reviews the effects of biochar application on growth, yield, physiology, and WUE of different vegetable crops under DI regimes to determine the potential of biochar and DI used in combination to sustain vegetable productivity in water-limited areas. Overall, the addition of biochar under DI has helped to compensate for yield losses of vegetables and further enhanced WUE. However, field studies investigating long-term soil–biochar interactions that strongly conclude the impact of biochar under moisture stress conditions are lacking.