Salt and Water Stress Influences Nitrogen Metabolism in Red Kidney Beans

Both salinity and water deficit reduce yields of crop plants. This study was an attempt to provide a better understanding of these stress effects on N metabolism and the utilization of NH 4 ‐N and NO 3 ‐N. Red kidney bean plants ( Phaseolus vulgaris L.) were grown under salt stress (NaCl), water stress (carbowax), and in a normal nutrient solution (control). The 15 N in NO 3 ‐ , NH 4 + , α‐amino acids, total soluble‐N, and protein‐N in plant shoots were analyzed after the plants received ( 15 NH 4 ) 2 SO 4 and K 15 NO 3 in nutrient solution for 6, 12, 24, and 48 hours. Sodium chloride and carbowax resulted in equal accumulations of NO 3 ‐ , NH 4 + , and free α‐amino acids in bean shoots. Protein synthesis was significantly reduced in bean shoots when the plants were subjected to NaCl salinity and carbowax, with either source of N, and the inhibition was more severe under salt stress than water stress.