Effect of sowing rate on the growth and yield of standard and semidwarf wheat cultivars

Two standard Wheat cultivars (‘Gamenya’ and ‘Triple Dirk’) and three semidwarf wheats (‘Matipo’, ‘Karamu’, and ‘Ciona-S’) were drilled at 77, 150, 216, and 284 kg/ha in the spring. Production and survival of tillers on permanently tagged plants were recorded at weekly intervals, and the number and weight of grains on the main stem and on the first, second, and remaining tillers of these plants were determined before the crop was harvested. Grain yield of the semidwarf wheats was 16% higher on average than that of the standard wheats, with no indication of any variety × sowing rate interactions for grain yield or any of its primary components (ears per unit area, grains per ear, and weight per grain). The tillering pattern of the semidwarf wheats was directly comparable with that of the standard wheats, and the yield superiority of the semidwarfs was largely due to their consistent advantage in total grain weight per ear. The ears on the main stems contributed 44% of grain yield at the lowest sowi...