Cell enlargement as an important factor in controlling grain weight in wheat

Grain dry weight, water content and changes in wall-bound a-galactosidase and P-glucosidase activities were estimated in three grains (differing in their position on the spike and final dry weight) of wheat (Triticum aestivum L.) cultivar Lok-1 during the entire period of grain development. Considerable differences in the grain weight within a wheat spike are reported, but the physiological and biochemical bases of these differences are poorly understood. The experiments described here indicate that the maximum grain weight is dependent upon the rate of grain filling. A highly significant correlation (P<0.001) between maximum grain weight and maximum water content per grain, and a close correspondence between the rate of grain filling and wall-located a-galactosidase activity, suggests that the process of cell enlargement may be important in determining the rate of grain filling, and thus, for maximum grain weight in wheat.