Effect of rootstocks on morphological and physiological traits of Sultana grapevine under moisture stress conditions

The effects of two Iranian grape rootstocks namely Kaj Anguor Bojnord (KA) and Qare Gandomeh (QG) with scion Sultana were studied in 2015 for drought stress, leaf structural characteristics and gas exchange parameters. Greenhouse grown, grapevines of cv. Sultana (Vitis vinifera L.) grafted onto two rootstocks and on own roots, were subjected to three drought stress levels (NS: no-stress, MS: moderate stress and SS: severe stress). The results indicated that under SS, relative water content in KA-grafted was similar to that in un-grafted Sultana under MS. Moreover, leaf area decreased under SS compared MS. Furthermore, KA-grafted exhibited the highest value of leaf fresh mass. The leaf dry mass for un-grafted Sultana was significantly lower than grafted vines and, the values of leaf tissue density for the three rootstocks were lower than control. Under MS, the leaf thickness of Sultana on KA exhibited an increase, while the other rootstocks followed a decreasing trend under SS. Also un-grafted Sultana had a higher specific leaf area compared to grafted vines. The amounts of leaf chlorophyll in Sultana on KA and QG were significantly higher than un-grafted vines. KA-grafted improved photosynthesis rate of Sultana scion compared to the own-rooted plants in all experimental drought conditions. Additionally, the transpiration for Sultana scion leaves had declined compared to un-grafted plants. Significant interactions were observed between stress levels and rootstocks on the water use efficiency. Concluding, in his experiment KA rootstock could be better performance compared to QG and un-grafted Sultana to drought stress.