Physiological Studies on Salinity and Nitrogen Interaction in Alfalfa Plants: III. Nitrate Reduc-Tase Activity

Nitrate reductase activity (NRA) was determined to investigate the effect of salinity and nitrogen (N) interactions on alfalfa [Medicago sativa (L) cv. Gilboa] during its vegetative growth. Increasing levels of sodium chloride (NaCl) (0,30, 65, and 100 mM) decreased NRA in both plant parts, i.e., root and leaf, however to a lesser extent in leaves. The inclusion of N either as nitrate (N03) or ammonium (NH4) (0, 3, and 6 mM) to the nutrient medium resulted in a substantial enhancement of NR activity in salinized and non-salinized plants as well.