Grafting height does not affect Fusarium wilt control or horticultural performance of Passiflora gibertii N.E.Br. rootstock

Abstract The influence of the grafting height (5, 10, 20 and 30 cm above the root collar) of P. edulis on P. gibertii was evaluated on the incidence of Fusarium wilt and horticultural performance. Plants of P. gibertii grafted on P. edulis and non-grafted plants of both species were also studied. In addition, histopathological studies were also performed on the roots of non-grafted P. edulis collected at three severity stages of Fusarium wilt. In greenhouse, the graft take was inversely related to the grafting height in general. In the field conditions, the plant growth of P. gibertii grafted on P. edulis was superior to its reciprocal grafting, even though the former combination was susceptible to Fop. Plants of P. edulis grafted on P. gibertii at all grafting heights did not present symptoms of Fop, and the number of fruit yield and quality were equivalent, but plant growth was decreased in relation to the non-grafted plants. Starch depletion in the root system of P. edulis was directly related to the severity of the Fusarium wilt. P. gibertii was confirmed as a Fusarium wilt resistant rootstock of P. edulis, with minimal influence of the grafting height for the control of the disease.摘要 本研究评估了西番莲（Passiflora edulis, P. edulis）的嫁接高度（根颈上方5、10、20及30 cm）对吉伯蒂西番莲（Passiflora gibertii, P. gibertii）镰刀菌枯萎病（Fusarium wilt）发病率及园艺性状表现的影响。本研究同时考察了以P. edulis为砧木嫁接的P. gibertii植株，以及两个物种各自的未嫁接个体。此外，本研究还针对采集自三个不同病情严重程度分级的镰刀菌枯萎病发病阶段的未嫁接P. edulis植株根系，开展了组织病理学研究。温室试验结果表明，总体而言嫁接成活率（graft take）与嫁接高度呈负相关关系。田间试验条件下，以P. edulis为砧木嫁接的P. gibertii植株生长性状优于正反嫁接（reciprocal grafting）组合，尽管前者组合对Fop敏感。所有嫁接高度下以P. gibertii为砧木嫁接的P. edulis植株均未表现出Fop感染症状，其果实产量与品质均与未嫁接植株相当，但植株生长性状较未嫁接植株有所下降。P. edulis根系内的淀粉耗竭程度与镰刀菌枯萎病的病情严重程度呈正相关关系。本研究证实P. gibertii可作为P. edulis抗镰刀菌枯萎病的砧木（rootstock），且嫁接高度对该病的防控效果影响极小。