Abstract

This study was conducted to elucidate the performance of varieties with known resistance genes of rice at two sites and assess the efficiency of the two sites for screening rice genotypes for blast resistance. Thirty-four (34) varieties plus one local check were screened for resistance to rice blast disease caused by a fungus (Magnaporthe oryzae) at Ibadan and Ikenne under natural infection for two years. The experiment was laid out using randomized complete block design with four replicates.Data were collected on disease development and severity using standard evaluation scale. Data were subjected to analysis of variance and the effect of genotype, environment, and their interaction were further analyzed using genotype main effect plus genotype-by-environment (GGE) biplot. Results revealed that the thirty-five varieties responded differently to blast infection and the two sites were significantly different from each other. Genotype-by-environment interaction was significant and had the highest contribution to the total sum of squares for disease development and severity scores. GGE biplot revealed that only Moroberekan was resistant to blast fungus across years and sites. In conclusion, although, the two sites are found in the same agroecology, Ibadan was identified as a better site for screening rice genotypes for blast resistance than Ikenne.

Key words: Blast fungus, disease severity, genotype-by-environment interaction,genotype-by-environment (GGE) biplot, rice.

Abbreviation

ANOVA, Analysis of variance; DAP, days after planting; GGE,genotype main effect plus genotype by environment interaction; IRRI, International Rice Research Institute; SES, standard evaluation scale.