Parasitismo de Meloidogyne enterolobii em espécies de Myrtaceae

Abstract

Guava tree root-knot, caused by M. enterolobii (= M. mayaguensis), is today regarded as the main phytosanitary problem of this crop all over the country, for its incidence results into marked yield fall and most of the time, the death of the plant on a medium term. Aiming at its control, it was intended in this study to identify resistance sources on guava tree, Psidium guajava L and Surinam cherry tree, Psidium sp. Eleven genotypes coming from the campus of the Federal University of Lavras (UFLA - Universidade Federal de Lavras) and regions close to Lavras (MG) were evaluated. The seeds were collected from physiologically ripe fruits and germinated in hydroponic pools. Reaching 12 cm high, they were transferred to the greenhouse in individual pots and kept at the temperature between 18 to 38°C. After fifteen days, they were inoculated with a suspension of 10,000 eggs and J2 of M. enterolobii and evaluated after 120 days. The hosts' reactions were fitted in the parameters established by the reproduction factor FR, estimated by the Pf/Pi quotient, where Pf stands for the final population and Pi the initial population and by the gall index (IG) and index of egg mass (IMO) through the score scale of the International Meloidogyne Project (IMP). The design utilized was the completely randomized with 11 genotypes, one nematode species and six replicates, that is, two plants in each genotype being added as a control. Four months later, the leaf contents of macro and micronutrients and degree of infection of each genotype were evaluated. The average yield of eggs and J2 of M. enterolobii ranged from 200 to 428,146.1 and the average reproduction factors (FR) varied from 0.02(ALU1) to 42.81(A-PASTO). The genotypes of Surinam cherry (Psidium spp.) AUFLA1, AUFLA4, AUFLA5 and APASTO and the genotypes of guava (P. guajava) G-ROXA and G-AMA were regarded as susceptible. The Surinam cherry genotypes ALU1, ALU2, ALU3, AROXO-C and AROXO-U proved resistant. Reinforcing the need for further studies with these species using as rootstock in commercial guava cultivars. The absorption of macro and micronutrients is altered when the genotypes of Psidium spp. are inoculated with phytonematode M. enterolobii.