| Abstract: | ABSTRACTIn this study, the physiological response of two cultivars of grapevine (Vitis vinifera cv. Rotabi, and Thompson seedless) was investigated under manganese treatment (manganese sulfate) and water stress conditions. In this regard, foliar application of manganese sulfate (MnSO4) treatment such as: 0, 2 and 4 g/l and water stress (WS) treatment including: without water stress (field capacity), moderate (?1 Mpa), severe (?1.5 Mpa) and very severe (?2 Mpa) was studied. Under MnSO4 treatment, the adverse effect of drought stress on Rotabi and Thompson Seedless vines were ameliorated considering plant height, dry weight of roots, root length, leaf surface area and number of leaves. In both cultivars, manganese treatment under drought stress produced higher total chlorophyll content, carbohydrate, proline and protein contents in vines than those of untreated ones. Furthermore, manganese treatment diminished the level of lipid peroxidation (MDA) and superoxide dismutase (SOD) activity in both cultivars. Also, it was found that the MnSO4 treatment could also increase the relative water content (RWC) in the grapevine leaves under water stress in Rotabi cultivar by 4% and Thompson seedless cultivar by 10% compared to control vines (0% MnSO4). The results obtained here suggest that foliar MnSO4 application can improve the growth parameters of grapevine under water stress and trigger protective mechanisms against water stress in grapevine, especially in Thompson seedless cultivar. |
