Response of Two Wheat Cultivars to Supplemental Nitrogen under Different Salinity Stress

Effects of supplemental nitrogen (N), as either farmyard manure (FYM) or urea, on response of two wheat (Triticum aestivum) cultivars (a salt sensitive ‘Sakha 69’ and a salt tolerant ‘Sakha 93’) were investigated in a green house experiment under various salinity levels (control, 6, 9, or 12 dS m-1). Grain and straw yields of both cultivars decreased with an increase in salinity levels. Supplamental N application, using FYM or urea, mitigated the adverse effects of salinity only at the low salinity level (6 dS m-1). This effect was greater in a salt tolerant cultivar (Sakha 93) than that in a salt sensitive cultivar (Sakha 69). At the moderate and high salinity (9 and 12 dS m-1) levels the supplemental N had no beneficial effects in mitigating the salinity stress of both cultivars. The mean grain yields, across all salinity levels and cultivars, of the plants received FYM and urea were greater by 11, and 8%, respectively, as compared to that of the plants received no supplemental N. The corresponding values for straw were 12 and 7%. The concentrations of N, P and K in the grain and straw significantly decreased with increasing salinity levels. Concentrations of Na, Cl, and Ca in the grain and straw were greater in salt sensitive cultivar than those in a salt tolerant cultivar. Concentrations of these elements significantly increased with an increase in salinity levels. This study demonstrated that supplemental N, as either FYM or as Urea, can mitigate negative effects of mild salinity stress, and that this beneficial effect was greater in a salt tolerant cultivar as compared to that in a salt sensitive cultivar.