Effects of zinc on growth, photosynthetic pigments, proline, carbohydrate and protein content of Lycopersicum esculentum under salinity

Zinc is one of micronutrients which reduces toxicity of sodium in plants and plays an important role in helping to the survival of crop plant under salinity stress. The research was conducted in a factorial experiment in completely randomized design with three replications in arak university in 1391 autumn. In this study، the effects of four salinity levels (0، 45، 90 and 120 mM NaCl) and three ZnSO4 levels (0، 5 and 10 μM) on tomato (Lycopersicum esculentum) were investigated. The results showed that single salinity decreased of the growth parameters، photosynthetic pigments and protein content، whereas increased the value of proline and carbohydrate in compared to the control plants. The results also showed that zinc treatment had positive effect on growth parameters، photosynthetic pigments، protein and carbohydrate content، however ZnSO4 treatment reduced the amounts of proline. Treatment of tomato plants under salinity stress with ZnSO4 reduced significantly the negative effects of salinity stress on these parameters. The highest values of growth indexes، photosynthetic pigments and protein were measured in plants without salt stress and concentrations of 10 μM Zn and the lowest values of this indicators were measured in plants under 120 mM NaCl without Zn. Therefore، it is recommended that for growing tomato in saline soils with zinc deficiency، Zn should be supplied in a adequate quantities to soils or used of ZnSO4 foliar sprays.