Utilizing maize maturity for drought avoidance purposes

Maize (Zea mays L.) grain yield is very dependent upon conditions relating to seed development. Drought stress causes maize yield reduction because water deficit and high temperatures often coincide with critical growth stages. Early-maturing maize might avoid late-season drought stress by decreasing development time. The objective of this study was to determine if early-maturing (relative maturity 95-98 day) maize hybrids would overcome potential yield advantage of late-maturing (relative maturity 115-118 day) maize hybrids and demonstrate physiological advantages when grown under dryland conditions in eastern Nebraska. Higher plant density than that considered optimum for late-maturing hybrids was used to manipulate light interception of all hybrids so that trends could be compared across a range of light interception values. Three early-maturing (\u27DeKalb DK-501\u27, \u27NC+ 2165\u27, \u27Pioneer 3737\u27) and three late-maturing (\u27DeKalb DK-646\u27, \u27NC+ 2165\u27, \u27Pioneer 3162\u27) maize hybrids recommended for dryland conditions in eastern Nebraska were grown at 25000, 45000, 65000, and 85000 plants ha$\sp{-1}$ in field studies at Mead and Lincoln, NE in 1991 and 1992. Analyses were combined across locations, but interactions with year prevented combining analyses across years. Lower grain yield and component parameters in 1991 than 1992 suggested higher water stress in 1991. Late-maturing hybrids experienced yield reduction at high plant density under high stress conditions. Early-maturing hybrids had inconsistent yield response at high plant density under high stress conditions. One early-maturing hybrid, Pioneer 3737, achieved similar yield when compared at similar values of canopy light interception and had higher and more stable radiation use efficiency than late-maturing hybrids under high stress conditions. A superior grain weight plant$\sp{-1}$ response of Pioneer 3737 compared to late-maturing hybrids as plant density increased was due to greater stability of seed number. This suggested a stress avoidance advantage derived from development timing, since seed number is determined during the maize plant\u27s most susceptible growth period. However, inconsistent yield and radiation use efficiency responses among early hybrids indicates variable adaptiveness of early-maturing hybrids for stress avoidance utilization in dryland long growing season environments