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.
Highlights
Rice (Oryzae spp.) is the most important staple food in the world today (Hawksworth, 1985) which has become part of everyday diet of many households
Results of the combined ANOVA performed across the two sites for 2009 and 2010 showed significant difference for variety, site, year and interactions for the two growth traits, disease severity and at all levels of blast disease development (Table 3)
Contribution of the different sources of variation to the observed total variation revealed that error, that is unaccounted sources of variation made the highest contribution to the total sum of squares (Table 3)
Summary
Rice (Oryzae spp.) is the most important staple food in the world today (Hawksworth, 1985) which has become part of everyday diet of many households. The population of people eating rice is about three billion, which is about half of the total world population. Rice is a staple food for over half the world's people and has the second largest cereal production after maize with over 685 million tons recorded in 2008 (FAOSTAT). According to the International Food Policy Research Institute (IFPRI), rice production needs to increase by 38% by 2030 in order to meet the demands of the growing world population. Nigeria is West Africa’s largest producer of rice, producing an average of 3.2 million tons of paddy rice for the past 5 to 6 years
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