Effect of cobalt treatments on dry matter production of wheat and DTPA extractable cobalt content in soils

The effect of different concentrations of cobalt added to two soil types, a sandy and a sandy loam soil, was studied on growth performance and tissue cobalt concentration of wheat plants. DTPA-extractable cobalt was significa ntly higher in the sandy soil than in the sandy loam soil. Plants grown in the sandy soil accumulated significantly higher amount of cobalt in compari son to plants grown in the sandy loam soil. Roots were significantly richer in cobalt than shoots in both the soil types. Lower (1 mu g g(-1)) adminis tration of cobalt resulted in an enhancement in the growth whereas higher ( 5-625 mu g g(-1)) addition inhibited growth. A significant inverse relation ship between relative wheat yield and tissue cobalt concentration was obser ved. The results indicate a possible requirement of cobalt for higher plant s.