Micronutrients

Treatment of pigeonpea seed with cobalt nitrate (500 tug kg‐1 seed) increased plant height, number of branches, leaves, total dry matter, and yield. The chlorophyll content, crop growth rate, relative growth rate, and net assimilation rate also increased significantly. Peanut seed treatment with cobalt nitrate (500 mg kg‐1 seed) followed by two foliar sprays before and after flowering (500 mg L‐1 water) increased plant height, leaf number and total dry matter. Pod yield, shelling percentage, test weight and harvest index increased significantly. In both crops nodule number and leghaemoglobin content also increased. Seed inoculation with rhizobium alone was not sufficient to reach maximum yield in both crops grown on the soil tested. Cobalt apparently improves nitrogen fixation by rhizobium, resulting in higher yield.