Salinity stress significantly decre

Salinity stress significantly decreases plant growth andyield production. However, in more tolerant crop plantshigher yields are produced under moderate salinityconditions. The unfavorable effects of salinity on wheatgrowth appears through: (1) decreased rate of seed germination,(2) reduced photosynthesis, (3) plant growthreduction, (4) decreased crop yield, (5) alteration ofenzymatic activities, (6) cellular damage, (7) oxidativestress, and (8) hormonal imbalance [22,25].The two important parameters, which determinecrop plant tolerance to salinity stress, are the adjustmentof osmotic potential under osmotically reducedwater availability and the controlling the cellular levelsof ROS. Puniran-Hartley et al. [42] investigated the roleof osmolytes in the salt tolerance of wheat and barley.Plants were subjected to salinity stress with 50–300mMNaCl, which resulted in the accumulation of leaf Naþ,especially in older leaves, compared with youngerleaves. The three major ions, including Kþ, Cl and Naþ,resulted in 67.7 and 70.4% of leaf osmotic potential inwheat and barley, respectively, under a salinity stress of200mM in older leaves, compared with the 43.9 and46.8% of osmotic potential in younger leaves.Osmolytes played an important role in the adjustmentof osmotic potential and hence the alleviation of saltstress in the two plants.According to the results of Lv et al. [43], the expressionof the genes including SeVP1 and SeVP2 in wheatand Arabidopsis can induce plant tolerance under salinitystress and N deficiency, respectively. The evaluationof plant responses under salinity stress is of utmostimportance for the production of tolerant crop plantsunder abiotic stresses. Accordingly, the response ofdurum wheat to salinity stress was investigated usingthe stable isotopes of 13C, 18O, and 15N. Salinityincreased plant 13C and 18O and decreased 15N [44].The authors indicated that under salinity stress Nmetabolism and decreased stomatal activity areamongst the factors affecting the plant’s response tosalinity stress. However, such a response is a function ofstress duration and severity, as well as the plant’sgrowth stage. The following parameters determine howsalinity stress may affect plant growth.