Genetic diversity of rice genotypes from Brazil based on their resistance to Pratylenchus zeae

摘要

A greenhouse study using naturally infested soil was conducted to evaluate the susceptibility of rice genotypes to Pratylenchus zeae and the broad-sense heritability of host resistance. Twenty-six rice genotypes were evaluated and maize 'BRAS 3010' and pearl millet 'AMN 17' were used as susceptible checks. Two variables, initial and final population densities and reproduction factor of P. zeae, were measured before sowing and 90 days after seed germination. The genotypes varied significantly in susceptibility to P. zeae. Heritability levels as high as 77.2 and 68 % for the reproduction factor and the number of nematodes per gram of roots, respectively, suggested that breeding rice for P. zeae resistance is difficult due to large environmental effects on the phenotypic expression of resistance.