Iranian Grapevine Rootstocks and Hormonal Effects on Graft Union, Growth and Antioxidant Responses of Asgari Seedless Grape

This research investigated physiological and biochemical changes at rootstock–scion union of graft combinations between Iranian rootstocks and Asgari scion in response to NAA and BAP application. Grafting cuts of scion and rootstock were dipped into NAA (0, 200 and 400 mg⋅L−1) and BAP (0, 250 and 500 mg⋅L−1) solutions for 30 min, immediately after the cuttings were grafted using the wedge grafting technique. The highest successful grafting rate (82%) was recorded with Asgari–Asgari combination treated with 200 mg⋅L−1 NAA + 500 mg⋅L−1 BAP. Treating the graft cut–surfaces with 200 mg⋅L−1 NAA + 500 mg⋅L−1 BAP caused the lowest H2O2 and MDA contents. Among all the graft combinations, the highest increase in chlorophyll content with a high photosynthesis efficiency occurred in Asgari–Shahani when treated with 200 mg⋅L−1 NAA + 500 mg⋅L−1 BAP. The graft union formation in the presence of 200 mg⋅L−1 NAA + 500 mg⋅L−1 BAP application enhanced CAT and POX activities. In conclusion, treatment of graft zone with 200 mg⋅L−1 NAA + 500 mg⋅L−1 BAP enhanced antioxidant activities and reduced lipid peroxidation in scion leaves. However, several grapevine rootstocks tested in our research were also impacting the scion performance.