SALINITY-FERTILITY INTERACTION ON GROWTH, MINERAL-COMPOSITION AND NITROGEN-METABOLISM OF INDIAN MUSTARD

Indian mustard (Brassica juncea L.) was grown under low fertility (LF) and improved fertility (IF) [60, 40, and 20 kg/ha N, P2O5, and K2O, r espectively] and irrigation with saline waters of different concentrat ions (0, 50, 100, and 150 meq/L) of the same composition as local grou nd waters. Although a progressive decline with increasing salinity was observed on all observed parameters, growth and seed yield was consis tently and significantly greater for the IF as compared to LF plants. The magnitude of the detrimental effects at increasing salinity was al so less in the IF as compared to the LF plants. These results suggest that an improvement in the concentration and uptake of NPK, particular ly N, and an increase in K:Na ratio under IF, stimulated nitrate reduc tase (NR) activity as well as the ammonia assimilating enzymes, such a s GS, GOGAT, and GDH, despite the high salinity. This led to higher le vels of free amino acids and soluble protein in the plants. Starch tis sue content also showed a marked increase. This suggests the importanc e of fertiliser treatment under salt stress.