Reação de genótipos de arroz de terras altas a Meloidogyne javanica

Abstract

Nematodes of the genus Meloidogyne, constitute an important group of plant parasites that cause damage to crops of economic importance. This study aimed to evaluate the resistance of upland rice genotypes to M. javanica, conducted in a greenhouse. Were used genotypic materials upland rice, originating from the breeding program of Embrapa Arroz e Feijão. The experimental design was completely randomized with 37 treatments and 36 genotypes of rice and cultivar soybean (BRSMG 760RR) as susceptible, and four replications each. The root-knot nematode populations were maintained on tomato plants, tobacco and soybeans. The rice plants were inoculated with 1000 eggs + second-stage juvenile (J2), 30 days after sowing. After 60 days inoculation the following variables were evaluated: fresh root mass (MFR), fresh and dry weight of shoots, number of egg mass, number of eggs + J2 per root system, for determining mass index eggs (IMO) and reproduction factor (FR), obtained by dividing the final population (Pf) and initial (Pi) of the nematode (FR = Pf / Pi). Was found the coefficient of linear correlation between the variables IMO x FR, IMO x MFR e MFR x Pf. The results indicated that 72% of the xiii genotypes of rice stood out positively with resistance the M. javanica, it was found that a larger population of nematodes in root, does not indicate lower root mass and leaf area. Furthermore, only mass index egg is not sufficient to determine the resistance or susceptibility of rice genotypes the M. javanica, being necessary to evaluate the reproduction factor. All correlations were significant and positive, indicating that the behavior of the evaluated parameters was always in the same direction.