Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi-110012
A comparison of variations in growth of grains in wheat cultivars Kalyansona and HD 2009 located at different positions within the spikelet and spikelets from basal, middle and apical portions of the ear with the endogenous levels of cytokinin, auxin like substances and inhibitors has shown that bolder grains (on weight basis), irrespective of location, were richer in the levels of cytokinin and two auxin like substances (Rf. 0.6–0.7 and 0.9–1.0)while the level of another auxin like substance (Rf, Ol-0.2)and two inhibitors (Rfs 0.5–0.6 and 0.8–0.9) were substantially lower than recorded in small sized grains. The results indicated that capacity of grains to grow and accumulate dry matter depended mainly on the levels of cytokinin and auxin like substances during the grain filling phase. Subsequent accumulation of inhibitory substances in larger proportions leads to the termination of grain growth.
