Yield and water use of drought-tolerant maize hybrids in a semiarid environment

Water shortage has been a challenge to sustainability of maize (Zea mays L.) production in many irrigated agriculture regions. Adoption of drought-tolerant (DT) hybrids could be a management strategy for maize production under water-limited conditions. The objective of this study was to investigate the differences in soil profile water extraction patterns at vegetative and grain filling stages, dynamics of evapotranspiration (ET), yield, and water use efficiency (WUE) in maize hybrids differing in drought tolerance characteristics in a semiarid environment. Field experiments were conducted in 2014 and 2015 in two conventional (33D53AM and N74R) and two DT hybrids (P1151AM and N75H). The hybrids were grown under two water regimes (Iloo and Is, referring to meet 100% and 50% of ET requirement, respectively). Comparing the well-watered plants at hoo, water stress at 'so reduced seasonal ET by 22-41%, grain yield by 30-48% and yield components by 6-41%; however, water stress only reduced WUE by 8%. Although the DT hybrids did not always provide yield benefit, the Pioneer AQUAmax. hybrid P1151AM had about 30% greater grain yield and WUE than the conventional hybrid 33D53AM. Regardless of year, water regime and hybrid, greater maize yield was related to greater biomass at maturity, harvest index, kernel weight and kernel number. Under water-limited conditions, two DT hybrids consistently had 3-6% lower seasonal ET than the two conventional hybrids. Compared with the conventional hybrids, the two DT hybrids extracted less soil water along the profile at vegetative stage. However, there were no significant differences in soil water extraction among hybrids during the reproductive stage. The results of this study demonstrated that effective use of soil water during grain filling is important for maintaining high yield under water limited conditions.