Assessment of resistance of hybrids and lineages of passion fruit to bacteriosis under protected cultivation

Abstract

Yield and longevity of yellow passion fruit have been reduced by diseases such as the bacterial spot caused by Xanthomonas axonopodis pv. passiflorae. Genetic resistance has been confirmed as the most efficient and economical correct option to minimize this disease problem. Aiming at it, the objective of this research was to evaluate the incidence, severity and progression of the disease in 12 genotypes of sour passion fruit, in seedling stage in nursery greenhouse after inoculation of Xanthomonas axonopodis pv. passiflorae. The inoculation was performed with an isolate collected in the Pipiripau Rural Nucleus, Brasilia-DF, named UnB-1397 (1x10⁶ CFU/mL), through induction of injuries. There were performed four assessments, with interval of 7 days except the first which was performed 11 days after inoculation. The incidence was estimated by the percentage of plants affected. To evaluate the severity, it was used the diagrammatic scale validated by Costa et al. (2018), with adaptations, using the measurement of the affected area by necrotic lesions on the leaf. All genotypes were susceptible to bacteriosis, 5 being considered moderately susceptible: F₁ BRS Pérola do Cerrado x Rosa Intenso, Mar20#21, Mar20#15b, Mar20#24xMar20#40 and FB200PL4R2 x Mar20#2005, with a mean of severity ranging from 11 to 25% of injured area in leaves.