Screening of Rice Accessions Resistant to Blast in Benin

Abstract

The objective of this screening is to identify genotypes with effective resistance genes against leaf blast. Two hundred rice accessions were collected in Benin's production areas and screened in upland ecology at Sowe (Glazoue, Benin). The experimental device used is an Alpha lattice 20 x 10 with 3 repetitions. The hierarchical ascending classification (HAC) allowed obtaining three large groups of accessions according to their behavior in relation to the populations of Magnaporthe oryzae present on the site: the C1 group composed of resistant genotypes (R), the group C2 composed of genotypes moderately sensitive (MS) and finally the group C3 that consists of sensitive genotypes (S). A highly significant difference was observed between genotypes based on recorded severity scores (five rating stages of disease and the AUDPC or Area Under the Disease Progress Curve). In general, the difference between the phenotypic variable (VP) and the genotypic variable (Vg) is relatively weak for all characters. All the traits studied had recorded high genotypic variation coefficients (GVC) and phenotypic variation coefficients (PVC) (> 20), with the exception of the first level of disease severity (Pyri1), thus justifying the high variability between genotypes with respect to resistance to disease. Heritability rate (H2%) coupled with high values of expected genetic gain compared to the mean (EGGM), indicated a low environmental influence in disease expression and a prevalence of the effect of additive genes in genetic determinism. The experiment has identified a pool of varieties with good behavior against blast disease that can be used as genetic control material in research and breeding programs in Benin.