RESPONSE OF MAIZE HYBRIDS TO VARYING POTASSIUM APPLICATION IN PAKISTAN

A field experiment was conducted in 2005 and 2006 to evaluate the growth, grain yield, N, P, K concentration in stalk, and quality parameters of three maize hybrids (Pioneer-30D55, Pioneer-3062 and Pioneer- 3012) at different levels of potassium (0, 100, 150, 200, and 250 kg ha^-1). Pioneer-30D55 surpassed other two hybrids in growth rate, grain yield (6.01 t ha^-1), N (0.728%), P (0.078%), K (1.79%) concentration in stalk, crude starch (72.97%), protein (8.15%) and oil (4.46%) contents in grains. K application in all treatments significantly increased growth rate, grain yield, N, P, K concentration in stalk, and improved crude starch, protein and oil contents in grains over control. Maximum growth rate, grain yield (6.05 t ha^-1 ), N (0.751% ), P (0.082%), K (1.86%) concentration in stalk, were recorded, when 200 kg K ha^-1 was applied, and beyond this limit, tended to decline its growth rate, grain yield (6.02 t ha^-1), N (0.743%), P (0.071%) and K (1.76%) concentration in stalk when 250 kg K ha^-1 was applied, but continued to increase crude starch (72.65%), protein (8.31%) and oil (4.53%) contents in grains. Interactive effects of maize hybrids and potash application levels on growth, yield and N, P, K concentration in stalk, crude starch, oil, and protein contents in grains were, however, non significant. It was concluded that Pioneer-30D55 performed best with 200 kg K ha^-1 when previous soil K status was 124.5 ppm. However, grain quality parameters were the best at 250 kg K ha^-1 application.