Does exogenous application of salicylic acid improve growth and some key physiological attributes in sunfl ower plants subjected to salt stress?

To appraise the effect of foliar-applied salicylic acid (SA) on growth and some key physiological attributes in sunflower plants under salt stress, a greenhouse experiment was conducted. Two sunflower lines (Hysun-33 and SF-187) were subjected to non-saline (control) and saline regimes (120 mM NaCl). After 14 days of initiation of salt treatment plants of both sunflower lines were supplied with varying levels (100, 200 and 300 mg L-1) of SA applied foliarly to all sunflower plants exposed to normal or saline substrates. After 21 days of SA application, data for growth (shoot biomass), photosynthetic pigments (chlorophyll a and b), water relation components, and accumulation of proline and mineral nutrients were recorded. Salt stress adversely affected the growth, chlorophyll pigments, water relations and contents of some key mineral nutrients, while increased the amount of proline and leaf and root Na+ as well as Cl- contents in both sunflower lines. Foliar-applied SA improved growth, chlorophyll a and b pigments, leaf turgor potential, and leaf and root Ca2+ concentrations. Of all salicylic acid levels used in the present study, 200 and 300 mg L-1 were found to be relatively more effective than the other levels in improving chlorophyll a and b pigments, leaf turgor potential, leaf and root Ca2+ concentration, while the other attributes remained unaffected due to SA application. Of both sunflower lines, Hysun-33 had higher amounts of photosynthetic pigments and essential nutrients than did SF-187