Biochemical Changes in Nodules of Vigna mungo (L.) During Vegetative and Reproductive Stages of Plant Growth in the Field

Abstract Nitrogenase activity in root nodules of Vigna mungo L. attained a peak at the flowering stage and declined thereafter. Levels of soluble proteins, particularly leghaemoglobin, and rates of protein and RNA synthesis declined with nitrogenase. Activities of protease and RNase increased with the ageing or nodules. Carbohydrate utilization, sugar levels and ATP were maximum at the early pod stage and gradually declined with age. These interrelated changes point to a loss of nitrogenase activity as the first indicator of nodule senescence that is linked with flowering. Later, losses of proteins, total sugar and ATP were related to increased RNase and protease activity and decreased hexokinase and to a loss in capacity to incorporate amino acid into protein.