کمی سازی مولفه های اصلی تحمل به شوری در تعدادی از ارقام گندم ایرانی

‭The problem of soil and water salinity is extending extremely in the world and it is a big challenge for food security. Many of this saline areas allocated to wheat cultivation annually as a strategic crop and productivity of this areas are more less than nonsaline soils. On the physiological point of view the cognition of nature of salinity effects on plants can be an essential tool for reduction of salinity effects. Based on the new theory, plants can be tolerate the salinity stress by mechanisms of osmotic tolerance, sodium exclusion and tissue tolerance. So this experiment carried out in order to quantifying of salinity tolerance components in Iranian wheat cultivars, which named as tolerance cultivars and determining of recovery after salt stress relief and also determining of the correlation of laboratory results and farm results. In greenhouse experiment, the pots filled with sandy medium and irrigated with nutrient solution, and the cultivars of Nishabour, Sistan, Arg, Ofogh, Roshan, Falat, KohDasht and Morvarid cultured in three replications as factorial and randomized complete block design. In the fourth leaf stages the signed pots treated with salinities of 2 and 15 decisimes per meter and continued for three weeks. After this time, the relative growth rate, accumulation of Na+ in leaf tissue and rate of necrosis and chlorosis due to salt stress was measured in order to determining and quantifying of salinity tolerance components. Also in some pots the salinities of 2, 7.5 and 15 decisimens per meter in three stages(emergence until tillering, tillering until end of season and emergence until end of season) treated on cultivars of Ofogh, Falat and KohDasht and measured growth recovery after salt stress relief. All of the cultivars planted in farm condition during 2 years (2012-13) with four replications as randomized complete block design and in two conditions of saline (Ag-Gala salinity station) and nonsaline (Gorgan station) to evaluation of yield of cultivars in real condition. Based on the results of the greenhouse experiment the mechanism of osmotic tolerance was more effective mechanism and then mechanisms of Na+ exclusion and tissue tolerance were next effective mechanisms respectively to determining of total salinity tolerance. Also, the cultivars which named as tolerance cultivars only had most effective Na+ exclusion mechanism than other cultivars. Based on other greenhouse experiment, the salt stress in initial growth stages was most important role to determination of final grain yield, so that salt stress relief in next growth stages couldn t be able to improve final yield significantly. Based on the two linear model of salinity response, the cultivars of Falat, KohDasht and Ofogh had the threshold values of 6.06, 5.27 and 4.00 decisimens per meter respectively. Based on sigmoidial model of salinity tolerance, this cultivars reached to 50 percent relative yield at salinities of 11.86, 11.56 and 13.38 decisimens per meter. Farm results showed that introduced cultivars which named as salt tolerance could be produced appropriate yields in saline condition only at introduced climatic condition and due to adaptation and when they cultured in different saline climatic condition, couldn t be able to access salt tolerance indices and produced less yields. Keywords: wheat cultivars, osmotic effects, ionic effects, stress tolerance mechanism, threshold value.‬