Bioaccumulation, Ionome and Physiological Responses to Copper Toxicity of Iranian Grapevine Rootstocks Grafted with ‘Asgari’ Seedless Grape

Use of proper rootstocks has the potential to improve copper (Cu) tolerance of grape. To evaluate the rootstock ability to reduce Cu transfer in the aerial portion of a grapevine, a glasshouse experiment was conducted to determine the physiological impact of Cu soil application in ‘Asgari’ seedless grape, either non-grafted or grafted onto different rootstocks. Vines were supplied with a nutrient solution at four levels of CuSO4 concentrations (0, 10, 25 and 50 µM). Cu toxicity symptoms in leaves and reduced plant growth rate were evident in the non-grafted ‘Asgari’ and less pronounced in grapevines grafted onto ‘Shahani’ rootstock. Moreover, ‘Asgari’ grafted onto ‘Shahani’ rootstock had lower rate of Cu accumulation in the leaves when compared to the roots than those of non-grafted and ‘Asgari’ with ‘Keshmeshi’ rootstock. Although significant reduction of P in non-grafted ‘Asgari’ leaf tissue was found under Cu toxicity, ‘Shahani’ rootstock reported the highest amount of P (5.94 mg g−1) in the leaves of ‘Asgari’ scion. However, significant fluctuations in terms of Ca and Fe were reported in leaves of both grafted and non-grafted ‘Asgari’. When exposed to Cu toxicity, ‘Shahani’ rootstock induced significant increase in chlorophyll content, Fv/Fm ratio and a noticeable reduction in electrolyte leakage, H2O2 and malondialdehyde (MDA) compared to those having ‘Keshmeshi’ rootstock and non-grafted ‘Asgari’. ‘Shahani’ rootstock improved ‘Asgari’ performance under Cu toxicity by slowly reducing the activity of antioxidant enzymes, preventing Cu accumulation in the aerial parts and maintaining a balanced scion nutritional status.