Response of seed germination and seedling growth of wheat (Triticum aestivum L.) cultivars to interactive effect of salinity and salicylic acid

Salinity is a major constraint in agricultural lands reducing growth and productivity of crops. Salicylic acid (SA) as a plant hormone is known to alleviate the adverse effects of many stresses including salinity. Therefore, in a series of experiments the effect of pre-sowing seed soaking with SA (0, 0.1 and 0.5 mM) on seed germination and seedling growth under NaCl (0, 150 and 200 mM) was studied in two contrasting wheat cultivars; Roshan (intolerant) and Mahdavi (tolerant). Salinity reduced germination percentage (GP), germination rate (GR) and vigor index (VI) in both cultivars and the effect of 200 mM was more severe. On the contrary, SA improved GP in both cultivars and VI in Roshan. Salinity reduced shoot growth, K+ uptake and K+/Na+ ratio and increased Na+ uptake and electrolyte leakage (EL) in leaf tissues of both cultivars. On the other hand, SA increased shoot dry weight (SDW), root dry weight (RDW) and K+ uptake and decreased Na+ content in shoots of cultivars and the effect of 0.5 mM was more pronounced. SA was effective in improving shoot length (SL) and EL only under salt stress conditions whereas shoot and root dry weight were improved under both stress and non-stress conditions. It is concluded that seed treatment with SA may promote germination and subsequent seedling growth of wheat cultivars under salinity conditions via maintaining cellular membrane integrity and reducing Na+ in favor of K+ accumulation in shoot.