The effect of MnSO4 on water stress tolerance in two cultivars of grapevine ‎‎(Vitis vinifera cv. L.) under in vitro condition

Drought is one of the most important abiotic stresses that have effect on growth and physiological aspect of grape. In this research effect of manganese sulfate on the morpho-physiological traits and superoxide dismutase enzyme activity in Thompson seedless and Rotabi grape cultivars under invitro at drought stress was evaluated. The manganese sulfate treatment was carried out across three levels, including MS without manganese (0 mg/L), MS with a standard manganese concentration (16.9 mg/L) and MS with twice the standard manganese concentration (33.8 mg/L), and the drought stress treatment was performed across four levels using 0, 3, 9 and 12% (w/v) solutions of polyethylene glycol (PEG) 6000 in two grape cultivars, namely seedless Thompson and Rotabi. The meristems of shoottip were used as explants. All growth parameters, including plant height, stem dry weight, leaf area, leaf number and relative water content (RWC) were reduced under the impact of drought. However, manganese sulfate treatment caused a significant increase in all these parameters at all concentrations. The highest amounts of superoxide dismutase enzyme activity was observed in 33.8 mg/L MnSO4 under drought stress with 12% PEG in the Rotabi cultivar (65.4 Umin-1g-1FW). The results of this research suggest that manganese sulfate treatment under invitro condition can improve water stress tolerance in both grapevines seedless Thompson and Rotabi cultivars.