Effects of a Brief Episode of Elevated Temperature on Grain Filling in Wheat Ears Cultured on Solutions of Sucrose

Abstract

The hypothesis that reduced grain weight resulting from elevated temperature is the result of a reduction in the supply of assimilates to the grain or lessened availability of sucrose within the endosperm for grain filling has been investigated. Detached ears of wheat were cultured on solutions of sucrose varying in concentration from a level which supports normal rates of grain filling to one above and one below that level. Contrary to expectation, at the low concentration of sucrose the rate of grain filling in detached ears increased more at elevated temperature than it did in ears supplied with higher concentrations of sucrose, or compared with ears developing on intact plants. In other experiments ears were detached and, after a brief exposure to elevated temperature, were cultured on solutions of sucrose. The residual effects of warming, expressed as slower grain filling and lower mature grain weight, were less pronounced at low than at higher concentrations of sucrose. This result also is not in accordance with the hypothesis.