Soil water extraction, water use, and grain yield by drought-tolerant maize on the Texas High Plains
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2015 Elsevier B.V. Anticipated water shortages pose a challenge to the sustainability of maize (Zea mays L.) production on the Texas High Plains. Adoption of drought-tolerant (DT) hybrids is a critical management strategy for maize production under water-limited conditions. However, limited information is available concerning water use by recently released DT hybrids. The objective of this study was to investigate the soil profile water extraction, evapotranspiration (ET), water use efficiency (WUE), and grain yield of one conventional and one DT hybrid. Field experiments were conducted in 2012 and 2013. The DT hybrid (AQUAmax P1151HR) and the conventional hybrid (33D49) were grown under three water regimes (I100, I75 and I50, referring to 100%, 75% and 50% of the ET requirement, respectively). The depth of soil water extraction was not affected by hybrid or water regime with the maximum extraction depth being 1.2-1.4m. Water extraction was higher at I50 than at I75 and I100. The maximum soil water extraction at I50, I75 and I100 occurred in 0.6-0.8m, 0.6-1.0m and 0.8-1.0m soil layers, respectively. Hybrid differences in soil water extraction were found in 2012, mainly at the grain-filling stage. At I100, P1151HR had less soil water extraction than 33D49. Under water stress conditions at I50, P1151HR had less soil water extraction in the upper soil layers but more water extraction in the deeper layers than 33D49. P1151HR had the same or less seasonal ET as compared to 33D49, indicating that the AQUAmax hybrid did not use more water than the conventional hybrid. P1151HR had higher yield and WUE than 33D49, particularly under the lower water regimes. On the average, yield and WUE of P1151HR were 6% and 9%, 14% and 17%, 24% and 30% higher than those of 33D49 at I100, I75 and I50, respectively. Higher yield of DT hybrid was associated with a higher biomass, a greater harvest index, and heavier kernel weight as compared to the conventional hybrid.
