Water Use and Grain Yield in Drought-Tolerant Maize in the Texas High Plains.

Anticipated water shortages will challenge the sustainability of maize production in the Texas High Plains. Adoption of drought tolerant maize hybrids is a critical strategy for maize production under water-limited conditions. However, little information is known about the difference in water use between drought-tolerant (DT) and conventional hybrid. The objective of this study was to compare water use and grain yield performance of two maize hybrids (one conventional and one DT hybrid) at three irrigation levels. Field study was conducted at the Texas A&M AgriLife Research Station near Etter, TX in 2012 and 2013 growing seasons. The experimental design was a split-plot two-factor randomized complete block design with Three replications. Irrigation treatment was the main plot factor and hybrid the subplot factor. Irrigation treatments consisted of 100% (I100), 75% (I75) and 50% (I50) evapotranspiration (ET) requirement and irrigation was carried out using a center pivot irrigation system.The same two hybrids with different drought tolerance were planted in both years: AQUAmax P1151HR and 33D49. P1151HR was designated as a DT hybrid. Measurements included soil water content, soil water extraction, seasonal ET, water use efficiency (WUE), biomass and grain yield. The results showed that grain yield, WUE, seasonal ET and biomass were significantly affected by water regimes and hybrids. Averaged across years and water regimes, P1151HR showed higher grain yield, WUE, biomass and lower seasonal ET compared to 33D49. In both seasons, the depth of soil water extraction was not influenced by hybrids and water regimes and the maximum extraction depth was 120-140 cm. Average across hybrids, soil profile water extraction was highest in I50 followed by I75 and I100. Compared to 33D49, P1151HR extracted less or similar amount of water from soil profile under different water regimes. In addition, P1151HR showed a greater ability to extract slightly more water from deeper soil layers under I50 in 2012.