Effects of Drought and High Temperature During Maturation on Preharvest Sprouting of Hard White Winter Wheat

Abstract

Preharvest sprouting of wheat (Triticum aestivum L.) is affected greatly by conditions after ripening, but effects of conditions during maturation are not clear. The objective of this research was to ascertain the effects of drought and high temperature during maturation on susceptibility of wheat to preharvest sprouting after ripening. ‘Betty’ hard white winter wheat was grown at 25/20 °C day/night until anthesis, when plants were subjected to no drought (field moisture capacity) and drought (−1.7 MPa leaf water potential) at 15/10, 22.5/17.5, and 30/25 °C until physiological maturity. Drought had little effect, but high temperature reduced all yield components. Neither stress affected α-amylase enzyme, but high temperature increased polyphenol oxidase enzyme, probably by increasing the proportion of bran in kernels. Grain protein percentage and SDS sedimentation were highest at the intermediate temperature. The germination promptness index of the grain, a measure of the rate and magnitude of sprouting, was increased by drought and unaffected by temperature. We concluded that drought during maturation increased susceptibility of wheat to preharvest sprouting, and high temperature reduced yield and might reduce quality of grain for noodles by increasing activity of polyphenol oxidase enzyme.