Results : Supply of 10-200 mM NaCl with 10 mM KNO3 for 24 h in continuous light reduced the overall growth of the bean seedlings, with perfect –ve correlation for seedling weight, root length and shoot length. Salinity effect with 10 mM NH4Cl was lesser and with 10 mM NH4NO3 was intermediary. NaCl treatment with 10 mM KNO3 reduced the fresh wt of the root as well as shoot tissue but increased in vivo NRA exerting strong correlation and more prominent effect in the root tissue. Very high NaCl concentration prominently increased NRA at 1, 10 and 50 mM KNO3 showing inverse gradation in effect. Salt treatment with NH4NO3, reduced the in vivo NRA of the root tissue, but the stress parameters, like proline and peroxidase were increased.
Conclusions : The salinity stress effects on NRA are less severe with NH4+, more prominent for root and more effective at low NO3- concentration. Inverse correlation between decrease in fresh mass and increase in NRA with salinity suggests the involvement of NR in the synthesis of nitric oxide and the observed effect of stress is the balance of two factors reduced assimilatory effect and increased nitric oxide stress. ER -