Arabica coffee progenies with multiple resistant to root-knot nematodes

Abstract

The root-knot nematode Meloidogyne paranaensis is considered the major threat in Coffea arabica plantations. Due to the aggressiveness of this nematode, cultivation is virtually impossible without a resistant cultivar. The main goal of this research was to identify resistant progenies derived from crossings of Catuai and Timor hybrid cultivars in a greenhouse experiment. Additionally, genetic parameters for resistance were estimated to trace selection strategies. Coffee plants were inoculated with 9000 M. paranaensis eggs and second-stage juveniles (J2). Eighty-six plants previously selected in a Meloydogine exigua infested field gave rise to 86 progenies that were evaluated based on the dry matter of aerial parts (DMAP), fresh matter of extracted root (FMER), height (H), and diameter (DIA). The responses of the progenies to nematodes were assessed using the gall index and thickness (GIT), number of eggs J2/g root (NEJGR), and reproduction factor (RF).The cultivars Mundo Novo IAC 379-19, Catuai Vermelho IAC 99, Paraiso MG H 419-1, and IPR 100 were used as susceptible and resistant controls. The GIT is genetically correlated with NEJGR and RF, and could be used in plant selection programs. Five progenies were resistant to M. paranaensis, with two of them not segregated to susceptibility. These progenies are considered multiple resistant to root-knot nematodes because they are also resistant to M. exigua.