Drought tolerance in maize is influenced by timing of drought stress initiation

Maize (Zea mays L.) yield loss due to drought is a common but often unpredictable occurrence worldwide. Approaches to mitigate yield loss include developing drought-tolerant hybrids and managing nitrogen (N) to optimize water use. Three experiments were conducted in Minnesota to compare drought-tolerant and standard maize hybrids under well-watered conditions and sustained moderate drought stress from the 14 leaf collar maize phenological stage (V14) or the blister maize phenological stage (R2) to physiological maturity. Three fertilizer N rates (guideline N rate [100%] or 50% higher and lower) were applied to each combination of hybrid and drought stress. Grain yield was 10% greater with the drought-tolerant than standard hybrid when drought stress began at V14, but did not differ between hybrids when drought stress began at R2 or in the absence of drought stress. Grain and silage yields with the 150% N rate were 7 and 12% greater for the drought-tolerant than the standard hybrid, respectively. Improved grain yield of the drought-tolerant hybrid when drought stress began at V14 was associated with greater aboveground biomass, N uptake, and kernel number. Hybrids exhibiting such characteristics may have enhanced ability to tolerate sustained moderate drought stress over a similar period of phenological development.