Screening World Vegetable Center eggplant and pepper rootstocks for resistance to Verticillium wilt

We carried out two separate field experiments to test resistance to Verticillium wilt (caused by Verticillium dahliae) of eggplant (Solanum melongena) and bell pepper (Capsicum annuum) grafted with rootstocks from the World Vegetable Center (WorldVeg; Tainan, Taiwan). The field site was naturally infested with V. dahliae at 14 cfu g(-1) of soil on average, and plants were inoculated with 104 cfu of V. dahliae at transplanting. For eggplant, 'Millionaire' was the non-grafted control, and was grafted onto 14 rootstocks. For pepper, 'Ace' was the non-grafted control and was grafted onto three rootstocks, and the experiment included non-grafted rootstocks. For eggplant, overall average area under the disease progress curve value was 190, V. dahliae was observed in stems of all treatments, and there were no significant differences due to treatment. 'Millionaire' grafted onto VI042738 had the greatest plant height, while the remaining treatments had plant height similar to non-grafted 'Millionaire'. Overall eggplant yield was very low (45 g plant(-1)), and both yield and fruit quality did not differ due to treatment. Contrastingly, none of the pepper treatments displayed symptoms of Verticillium wilt, no V. dahliae was recovered from stem samples, and there was no difference in yield among treatments (341 g plant(-1) on average). However, plant height of 'Ace' grafted onto VI014995 and VI037556 was 30% less than non-grafted 'Ace'. Thus, at the disease level in this study, grafting eggplant onto WorldVeg rootstocks did not provide a benefit, while pepper and the rootstocks demonstrated resistance to the isolate of V. dahliae at the experimental site. The pepper used in this study could potentially be used as a rotation crop in fields with this isolate of V. dahliae.