THE INFLUENCE OF POTASSIUM SUPPLY ON NODULATION, NITROGENASE ACTIVITYAND NITROGEN ACCUMULATION OF SOYBEAN (GLYCINE-MAX L MERRILL) GROWN INNUTRIENT SOLUTION

The influence of potassium nutrition on dry matter yield, nodulation, N accumulation and nitrogenase activity of soybean were studied under controlled conditions in hydrophonic and sand culture at 4 levels of K in a nutrient medium (1.0, 5.0, 10.0 and 20.0 mM). The dry matter yie ld, nodule parameters (nodule number and fresh weight of nodule per pl ant, average weight of nodule) and total nitrogen accumulation in the plant increased with increasing K-supply. The lowest potassium level, 1.0 mM was suboptimal for normal growth, nodulation and N-accumulation , whereas 5.0 mM K was found to be an optimal level for these same par ameters. However, the nitrogenase activity, which was determined non-d estructively, was not affected by an increased supply of K.