Reação de acessos de melão ao parasitismo de Meloidogyne spp.

Abstract

The melon (Cucumis melo L.) is widely cultivated in the Northeast region of Brazil and is a prominent crop in the country's agricultural exports. With the expansion of the crop, biotic stresses are common during its development, and one of the most common pathogens is the root-knot nematodes (Meloidogyne spp.), which cause inefficiency in the absorption of water and nutrients by the root system, resulting in leaf wilting and affecting plant growth. The most appropriate control method is the use of resistant cultivars. Thus, the aim of this study was to evaluate the reaction of melon accessions to parasitism by Meloidogyne javanica and Meloidogyne enterolobii. Therefore, two independent experiments were conducted in a greenhouse, one for each nematode species. The variables (number of galls, juveniles on roots, eggs on roots, juveniles in soil, nematodes per gram of roots, reproduction factor, reproduction factor reduction and reproduction index) were analyzed in the Phytopathology Laboratory from the Science and Agrifood Technology Center, at Federal University of Campina Grande (UFCG), Pombal Campus, located in the state of Paraíba. A completely randomized design with five replicates was used, with each useful plot consisting of one plant. Ten accessions were used: AC 02, AC 25, AC 04, AC 05, AC 07, AC 08, AC 09, AC 10, AC 27 and AC 14 from the melon germplasm collection provided by the Federal Rural University of the Semi-Arid Region (UFERSA), as well as a Santa Clara tomato cultivar used as a susceptibility standard. Each plot was inoculated with 5,000 second-stage eggs/juveniles, which were distributed in holes around the plants using a test tube applied separately. Fifty days after inoculation, the resistance of the accessions was evaluated based on parasitism variables. All the melon accessions showed some level of resistance to M. javanica and M. enterolobii, taking into account the reproduction index (RI), reproduction factor (FR) and reproduction factor reduction (RFR). Among the melon accessions studied, AC 02, AC 25 and AC 04 demonstrated the most effective resistance to parasitism by both species of root-knot nematodes, and could be used as studies in genetic improvement programs.