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Guar, [Cyamopsis tetragonoloba (L.) Taub] is an annual summer legume that is widely grown in arid and semi-arid regions. It is a diploid legume (2n = 2x = 14) with a genome size of approximately 560 Mb. Guar can fix atmospheric nitrogen via a symbiotic process with rhizobial bacteria, thus enhancing soil fertility and decreasing the need for the use of expensive nitrogen (N) fertilizers. Guar is a drought- and heat-tolerant crop and can be grown using minimal agricultural inputs. Guar can be used as vegetable, feed/fodder, or green manure. One of the primary driving factors for guar cultivation is galactomannan gum, known as guar gum, found in the seed endosperm. Guar gum has various industrial uses that range from cosmetic applications, food ingredients, to the oil industries. India is the lead guar production and accounts for more than 80% of the world production. The U.S. is the world largest guar market. This review discusses the status of genomic resources in guar, the progress made for germplasm evaluation of various agronomic traits, and the genetic engineering efforts in guar.

The purpose of this study is to evaluate the state of knowledge regarding water for food within the water-energy-food (WEF) nexus framework. Three topics are considered: improved plant genetics; irrigation technology and practices; and urban agriculture. Research in plant genetics has sought to understand plant mechanisms that produce higher-yielding crops, identify and map genetic loci regions responsible for desirable plant traits, and introduce new and safe methods of precision plant breeding. In addition, new discoveries in irrigation practices are crucial in sustaining and further increasing yields as a result of improved irrigation water use efficiency through near-real time spatio-temporal monitoring of soil moisture, evapotranspiration, and rainfall. Urban agriculture has been proliferating in recent years, and recent research demonstrates the possibility of non-traditional, urban farming methods to produce food in a water- and land-efficient way. Opportunities remain to increase water use efficiency and/or decrease water usage throughout the food supply chain. Food producers need to achieve greater value from the water used through enhanced management supported by new technology and guided by scientific findings evolving from multidisciplinary research. To achieve this, constant exchange is needed between regulatory agencies, farmers, food manufacturers, and researchers to ensure all stakeholders are up to date on the issues, policies, technologies, and discoveries related to water and food production sustainability.

Bioenergy crop production has the potential to protect marginal crop lands that generate high surface runoff and produce poor crop yields. Long-term evaluation of the impacts of such land use change on hydrologic fluxes and biofuel production potential is necessary before adopting such strategies on a large scale. In this study, the hydrologic impacts of replacing cotton (Gossypium hirsutum L.) on marginal lands in an intensive agricultural watershed in the Texas High Plains with Alamo switchgrass (Panicum virgatum L.) as a bioenergy crop were evaluated using the Agricultural Policy/Environmental eXtender (APEX) model. The surface runoff to cotton yield ratio was used as a criterion to identify marginal cotton subareas (homogenous spatial units delineated by APEX) in the study watershed, and three replacement scenarios (low (9 %), medium (33 %), and high (57 %) extents of cotton acreage replaced by switchgrass) were implemented in the scenario analysis. The average (1994–2009) annual surface runoff decreased by about 84 and 66 %, and the percolation increased by 106 and 57 % in the irrigated and dryland subareas, respectively, when cotton was replaced by switchgrass under the high replacement scenario. Spatial analysis showed that switchgrass was a feasible bioenergy crop for replacing cotton, especially in the western part of the study watershed, due to its higher water use efficiency and better water conservation effects compared to cotton. It is estimated that 193 and 381 million liters of ethanol could be produced from the dryland and irrigated subareas of the study watershed, respectively, under the high replacement scenario.

Potential changes in future climate in the Texas Plains region were investigated in the context of agriculture by analyzing three climate model projections under the A2 climate scenario (medium–high emission scenario). Spatially downscaled historic (1971–2000) and future (2041–2070) climate datasets (rainfall and temperature) were downloaded from the North American Regional Climate Change Assessment Program (NARCCAP). Climate variables predicted by three regional climate models (RCMs) namely the Regional Climate Model Version3–Geophysical Fluid Dynamics Laboratory (RCM3-GFDL), Regional Climate Model Version3–Third Generation Coupled Global Climate Model (RCM3-CGCM3), and Canadian Regional Climate Model–Community Climate System Model (CRCM-CCSM) were evaluated in this study. Gaussian and Gamma distribution mapping techniques were employed to remove the bias in temperature and rainfall data, respectively. Both the minimum and maximum temperatures across the study region in the future showed an upward trend, with the temperatures increasing in the range of 1.9 to 2.9 °C and 2.0 to 3.2 °C, respectively. All three climate models predicted a decline in rainfall within a range of 30 to 127 mm in majority of counties across the study region. In addition, they predicted an increase in the intensity of extreme rainfall events in the future. The frost-free season as predicted by the three models showed an increase by 2.6–3.4 weeks across the region, and the number of frost days declined by 17.9 to 30 %. Overall, these projections indicate considerable changes to the climate in the Texas Plains region in the future, and these changes could potentially impact agriculture in this region.

Aquifer-based groundwater quality assessment offers critical insight into the major hydrochemical processes, and aids in making groundwater resources management decisions. The Texas Rolling Plains (TRP), spanning over 22 counties, is a major agro-ecological region in Texas from where highest groundwater nitrate (NO3 −) levels in the state have been reported. In this study, we present a comparative assessment of major hydrochemical facies pertaining to NO3 − contamination and a host of species such as sulfate (SO4 2−), chloride (Cl−), and total dissolved solids (TDS) in different water use classes in the Seymour and Blaine aquifers, underlying the TRP. Aquifer-stratified groundwater quality information from 1990 to 2010 was obtained from the Texas Water Development Board and aggregated over decadal scale. High groundwater salinization was found in the municipal water use class in the Blaine aquifer with about 100, 87 and 50 % of observations exceeding the secondary maximum contaminant level for TDS, SO4 2−, and Cl−, respectively in the 2000s (2000–2010). The NO3-contamination was more alarming in the Seymour aquifer with 82 and 61 % of observations, respectively, exceeding the maximum contaminant level (MCL) in the irrigation and municipal water use classes in the 2000s. Salinization was more influenced by SO4 2− and Cl− in the Blaine aquifer and by NO3 − in the Seymour aquifer. High NO3 − (>MCL) observations in the Seymour aquifer occurred in the Ca–HCO3 and Ca–Mg–HCO3 facies, the domains of fresh water recharge and anthropogenic influences (e.g., agricultural activities, waste disposal). High SO4 2−, Cl− and TDS observations in the Blaine aquifer dominated the Ca–Cl, Na–Cl, and mixed Ca(Mg)–SO4(Cl) facies indicating evaporite dissolution, mixing and solute exchange, and lack of fresh recharge.