Impact of biological and chemical treatments on the improvement of salt tolerance in wheat

Salinity stress has been known as an important constraint limiting agricultural production especially in arid and semi-arid regions. Among several strategies to improve crop growth under salt stress, using of salinity tolerant Trichoderma isolates and silicon application could be an effective and easily adaptive strategy. In order to evaluate silicon and Trichoderma virens inoculation effects on some physiological and morphological properties of wheat grown under saline condition, a greenhouse experiment arranged as factorial based on completely randomized design with three replications was carried out. The factors included three levels of salinity (E1:3, E2:7 and E3: 10 dS m−1) from NaCl, CaCl2 and MgCl2 sources (3:2:1 ratio, respectively), two levels of Si, 0 (S1) and 1.5 mM (S2), from the source of Na2SiO3 and two levels of Trichoderma virens (with and without inoculation). It was shown that salt stress caused very significant reduction in plant height, chlorophyll content, grain yield and other measured properties. Salinity stress increased proline and soluble sugar concentration, Na/K and Na/Ca ratios in leaves. Application of Si to the growth medium significantly increased chlorophyll content, grain yield of wheat grown under normal as well as under saline environments, but those influences were lower than the fungus effect. These results seem to show that silicon may alleviate salt stress in wheat due to decreased Na/K and Na/Ca ratios and proline concentration in leaves. Tirchoderma inoculation significantly increased chlorophyll content and grain yield of wheat under salt stress. Trichoderma virens deteriorate salt stress by significantly decreasing Na/K and Na/Ca ratios and proline concentration and increasing soluble sugar in the leaves.