Effect of exogenous application of cytokinin on yielding ability of developing grains at different locations within same spike or spikelet in wheat

Effect of exogenous kinetin (KN) on yielding ability of developing grains was evaluated at different locations within same spike or spikelet of wheat (Triticum aestivum L. var. PBW-343). The plants were grown in a screen covered hall under otherwise natural conditions. An aqueous solution of 100 ppm kinetin was sprayed at 3 ml plant -1 at panicle initiation. Main spikes were divided into three grain positions included proximal, middle, and distal regions, and further into two grain types included basal (bold) and apical (small) grains. Dry matter accumulation, absolute and relative growth rate levels were determined in ten labelled spikes which sampled nine times, four-day intervals started from seventh day after anthesis (DAA) up to 35 th DAA, and at maturity. The exogenous applications of the cytokinin (kinetin), wherever applicable, improved the precipitation potential of smaller grains with more vigour as compared to the bolder grains e.g., the increase in weight of smaller grains at maturity ranged between 14.8 to 32.1 percents in three different segments of spike. However, the augmentation in case of bolder grains was in the range of 7.5 to 8.8 percents. The results suggest that a higher grain weight as indicative of capacity of grain to grow, was associated with higher endogenous levels of cytokinins and an exogenous application of cytokinin drifted the metabolism of smaller grains in the direction what was in operation in bolder grains.