Remobilization of labelled nitrogen from vegetative tissues to pods of mungbean

Summary Remobilization of¹⁵N from vegetative tissue of mungbean (Vigna radiata (L.) Wilczek) into pods was measured during the reproductive phase of growth. Plant tissue was labelled with¹⁵N during vegetative development. Experiments were conducted in the field at two sites. At one site the soil provided cowpeas with most of their N but at the other site N fixation provided most of the N. Remobilized N from vegetative tissue to pods occurred soon after they began to develop. The quantity of the labelled N ultimately remobilized to the pods amounted to 50% for one cultivar (Tx33) at the high soil N site and 70% at the low N site. For the other cultivar (Tx13) the values were 25% and 30%, respectively. The two cultivars performed very differently with respect to partitioning of N into pods and the rate of N fixation. Even though more N was accumulated in the shoots of the high N fixing cultivar (Tx13) less total N was contained in the pods.