Water uptake in relation to pre-harvest sprouting damage in wheat: grain characteristics

Abstract

Water uptake by mature (post-dormancy) wheat grain was studied for a group of 50 wheat varieties of mostly Australian origin and in lines near-isogenic for grain coat colour (red v. white) and for hard v. soft grain. Cultivars differed widely (up to two-fold) in grain water uptake. Apparently these differences related to physico-chemical aspects of water imbibition by the grain. However, neither grain coat colour, pericarp or testa thickness, grain hardness nor grain protein content was correlated with grain water uptake. The degree of seed coat cracking was minimal as grain was dissected by hand from the ears. Grain germination after 30 h exposure to moisture was significantly correlated with its water uptake after 2 h of imbibition (r = 0.61). These findings, when combined with other information from this laboratory on varietal differences in ear water uptake, usefully characterize in-ear sprouting. Of the varietal differences in sprouting, 18% can be accounted for by differences in ear and grain water uptake. Differences in grain dormancy were deliberately avoided in these studies, but were evaluated separately at harvest ripeness in this same experiment. On the basis of varietal differences in grain dormancy and water uptake some breeding options are highlighted.