Maize ( Zea mays L.) response to a severe soil water-deficit during grain-filling

Abstract

Factors which reduce the rate or duration of grain-filling usually are detrimental to grain-yield. The effects of a severe soil water-deficit during the grain-filling period were studied for two commercial maize hybrids grown under field conditions utilizing a rain shelter. Two planting dates provided a range in the developmental stage at which deficits were imposed. Objectives were to compare the influence of the water-deficit on biomass accumulation, rate and duration of kernel-filling, kernel numbers, kernel size distribution, and final yield against an irrigated control. Deficit plants had less green leaf area during grain-filling due to early senescence. Above-ground biomass at the end of the growing season was 23–36% less for deficit plants than for irrigated control plants. Yield reductions ranged from 21% to 40% for the water-deficit treatments, with kernel weight being the most affected component. Individual kernel samples indicated that duration of the linear kernel-filling phase was shortened by as much as 8 days, whereas rate of single kernel-filling was not significantly reduced by the water shortages. There was a larger percentage of kernels weighing less than 100 mg for deficit plants, which reflected the abbreviated kernel-filling period.