Salicylic acid induced changes on some physiological parameters in tomato grown under salinity
Salinity is a major environmental constraint to crop productivity throughout the arid and semi arid regions of the world. The development of strategies to ameliorate deleterious effects of salt stress on plants has received considerable attention. Salicylic acid (SA) has been shown as an important signal molecule for modulating plant responses to environmental stress. In addition to facilitating the growth of plant, SA has been shown to play a role in mitigating the deleterious effects of some environmental stresses. Therefore, an experiment was conducted to investigate the impact of exogenous salicylic acid (0.01 mM) on some physiological parameters in tomato (Solanum lycopersicum, cv Marmande) grown under salinity stress (NaCl 100 mM). Dry yield of the plants decreased significantly with exposure to NaCl. Exogenous application of SA (0.01 mM), increased dry weight both in saline and non-saline conditions. In saline conditions, with the applied SA, dry yield increased almost up to the yield obtained from non-saline conditions. Salt stress increased membrane permeability of leaves. Exogenously applied SA decreased the membrane deterioration. NaCl reduced photosynthetic pigments contents. Whereas, the addition of SA induced an increase of these contents. Under salinity stress, the amounts of Na, Cl and Na/K ratio severely increased and the amount of K, Ca and Mg decreased. Addition of SA in the culture medium inhibited Na+ and Cl- accumulation, but stimulated K+, Ca2+ and Mg2+ contents of stressed plants. These results suggest that SA could be used as a potential growth regulator to improve plant resistance to salinity stress.