Changes in metabolism and biochemical composition in response to micronutrient limitations in cowpea

To study the response of manganese (Mn), copper (Cu) and boron (B) deficiency on metabolism and developmental aberration in biochemical composition, cowpea (Vigna unguiculata L.) cv. Pusa Komal was grown in refined sand at adequate (complete nutrient solution) and three deficient levels of Mn (2 μM), Cu (0.1 μM) and B (3 μM). Plants subjected to deficient supply developed characteristic foliar symptoms of each deficiency accompanied by marked depression in growth, dry matter, economic yield, total seed protein, concentration of Mn, Cu and B, chlorophyll content and Hill reaction activity. Exposure of cowpea plants to each deficiency induced changes in enzyme activities of peroxidase, acid phosphatase, ribonuclease, polyphenol oxidase and altered the concentration of sugar, starch and phenols in leaves and seeds indicating specific role of these micronutrients in metabolism and deposition of reserves in the seeds during seed setting of cowpea.