NITROGEN DISTRIBUTION INDEX OF CAJANUS-CAJAN L DURING DROUGHT AND REHYDRATION

Relative competition among various plant parts for N during water stre ss, i.e. nitrogen distribution index (NDI) was determined in relation to specific nitrogenase activity (SNA) and nodule and soil nitrogen in both indeterminate (H-77-216) and determinate (ICPL-151) types of pig eonpea (Cajanus cajan L.) under greenhouse conditions. Two levels of w ater stress, i.e. moderate (soil psi(W)-0,77 MPa) and severe (soil psi (W)-1.34 MPa) were created by witholding the irrigation at vegetative (40 DAS) and flowering (70 DAS) stages. At vegetative stage under mode rate stress the highest NDI was in nodules of cv. H-77-216 and in leaf of cv. ICPL-151. Under severe stress both the cultivars showed negati ve values of NDI, with maximum loss of N from root and nodules. Cultiv ar ICPL-151 behaved differently at flowering and vegetative stages. Ve ry high loss of N from different plant parts was seen at flowering und er severe stress. All the plant parts showed gain in N during rehydrat ion. Loss and gain in N at both the stages under stress and rehydratio n respectively, correlated with available N in soil. Specific nitrogen ase activity (SNA) and nodule N were maximum at moderate stress and re lated with NDI values of leaf and nodules.