Influence of exogenously applied brassinosteroids on the mineral nutrient status of two wheat cultivars grown under saline conditions

In order to assess the influence of exogenous application of varying concentrations of brassinosterioids as a foliar spray in inducing salt tolerance in wheat (Triticum aestivum L.), a seedling experiment was conducted in small plastic pots. A salt tolerant S-24 and a moderately salt sensitive MH-97 were grown under normal or saline conditions (150 mM NaCl) for two weeks. Varying concentrations of 24-epibrassinolide (24-epiBL) were foliarly applied @ 0 (water spray), 0.001, 0.025, 0.050, 0.075, 0.10, 0.125, 0.150, 0.175, and 0.20 mg L-1 on two wheat cultivars. S-24 and MH-97. Salt stress reduced the growth of both cultivars. However, this inhibitory effect of salt stress was less on S-24. Foliar application of brassinosteroids improved the growth. However, a maximum increase in growth of both cultivars was observed at 0.125 mg/L of BRs. Furthermore, higher concentration of brassinosteroids did not improve the growth of both wheat cultivars under normal or saline conditions. Foliar spray of brassinosteriods reduced leaf Na+, and enhanced leaf K+, leaf Ca2+, and K+/Na+ ratios, while Cl- was inconsistently increased or decreased with increasing level of brassinosteriods. Overall, salt-induced reduction in growth of wheat cultivars was alleviated by foliarly applied brassinosteriods. However, the effectiveness of brassinosteroids in ameliorating the adverse effects of salt stress depends upon the concentration applied. Brassinosteroids improved Ca 2+/Na+ and K+/Na+ ratio of wheat cultivars by enhancing uptake of Ca-+ and K+ and reducing that of Na+, which might have contributed to the salt tolerance of both wheat cultivars.