Priming-induced antioxidative responses in two wheat cultivars under saline stress

Wheat, a glycophyte grown in tropical and subtropical regions, is frequently being subjected to soil salinity ultimately affecting the plant growth and yield. Focus of the present study was to evaluate the ameliorative efficiency of different seed priming methods including hydropriming and halopriming [KCl and CaCl₂ (100 mM)] by observing change in the expression of antioxidant defense system and accumulation of phenolic as well as proline in the spring wheat Lu26s (salt tolerant) and Lasani-06 (salt sensitive), grown under salt stress of 100 mM NaCl. Results showed that salt stress provoked a marked decline in germination, growth and yield parameters as well as increased lipid peroxidation and hydrogen peroxide (H₂O₂) contents. However, higher accumulation of proline and low H₂O₂ contents were recorded in both cultivars under halopriming followed by hydropriming. Halopriming induced a significant increase in antioxidant enzyme activities (CAT, POD, APX) of salt-tolerant cultivar Lu26s, whereas such pattern of enhanced activities of antioxidant enzymes in cultivar Lasani-06 was also found but the content of these activities was less than control under saline regime. The cultivar Lu26s (salt tolerant) maintained lower Na⁺ and higher K⁺/Na⁺ ratio in leaves than salt-sensitive cultivar Lasani-06. Reason behind the loss of grain yield under salinity was found due to the reduction in the grain spike⁻¹ in cultivar Lasani-06, while, in cultivar Lu26s, it was due to decrease in the size of grains. Enhanced germination, low proline and Na⁺ contents stimulated antioxidant activities as well as phenolic contents associated with improved salt tolerance in haloprimed plants. These results suggest that halopriming is an efficient approach for imparting tolerance in wheat against salinity stress.