Population parameters and correlation among characteristics of the resistance to root-knot nematodes in lettuce

Abstract

The aim of this work was to estimate population parameters and to quantify the association degree among the characteristics related to Meloidogyne incognita race 1 resistance in lettuce F₄, in order to contribute improvement programs in the incorporation of the resistance to root-knot nematodes. The experiment was carried out in a greenhouse, using expanded polystyrene trays with 128 cells, in a completely randomized blocks design with three replications and eight plants per plot. The substrate was infested with Meloidogyne incognita race 1 eggs, in the proportion of 30 eggs.cm^–3 of substrate. The evaluation was made 45 days after the inoculation for galls incidence, galls number, eggs masses number and eggs number. The estimated high  broad heritability was higher than 45%, reaching 72% for eggs number. High and positive genetic correlation exists among all of the evaluated characters and the eggs number provides the greatest gain of selection.