Salicylic acid versus salinity-drought-induced stress on wheat seedlings

The rise of NaCl level and drought treatment, generally, exhibited an inhibitory effect on the growth rate, leaf area and transpiration rate of wheat seedlings. The water content of either shoots or roots was mostly unchanged except in shoots of 70% and roots of 30% droughted plant, where it decreased at increased salinity. On the contrary, the chlorophyll and carotenoid contents, net photosynthetic rate and dark respiration rate were raised in plants subjected to both salinity and drought. Soaking of wheat grains for 6 h in 100 ppm, salicylic acid before sowing was generally effective in antagonizing partially or completely the stressing effects of NaCl (40, 80, 120 and 160 mM) and drought (70, 50 and 30% field capacity) on growth rate, leaf area and transpiration rate. On the other side, salicylic acid enhanced the stimulatory effect of NaCl-drought on photosynthetic pigments, net photosynthesis and dark respiration of seedlings (30-day-old). Soaking of wheat grains in salicylic acid exhibited a favorable effect on the accumulation of some ions and antagonized or ameliorated the inhibitory effect of salt-drought stress on some others.