Screening of rice genotypes for African rice gall midge resistance in Southern Guinea agro-ecological zone of Nigeria

Abstract

The major biotic constraint related with lowland rice production is African rice gall midge (AfRGM), and one way which has proved successful in management of this pest is varietal resistance or tolerance. In this study, screening of genotypes was conducted to identify the resistant/tolerant cultivars of low-land rice under AfRGM infestation. Field experiments were conducted in 2017 cropping season at Badeggi and Edozhigi to screen 81 rice genotypes. The field was laid out in an Alpha Lattice Design, comprising of 5 blocks with 17 plots in each block and replicated three times. Gall midge was scored at 42 and 63 days after transplanting, while other parameters, including days to 50 % flowering and grain yield were also recorded. All genotypes exhibited a wide and significant (p<0.05) variation. The highest phenotypic and genotypic coefficient of variation was recorded for the panicle exertion and the highest heritability was found for panicle length, grain yield and panicle exertion. Correlation analysis revealed that days to 50 % flowering was highly significant (p<0.05) and correlated positively (0.559**) with African rice gall midge. Grain yield did not correlate significantly (p>0.05) with AfRGM while there were strong, positive and significant correlation between tiller counts and panicle (0.961**) counts. However, genotype G007 (HK71-NCRIJ-3-1) which was the only one found to be moderately resistant with (5.34 %) tiller infestation, all other genotypes ranged from susceptible to highly susceptible. Genotypes G015, G030, G045, G046, G051 and G068 gave better yield under Gall midge infestation compared with the checks and it could be recommended for crop improvement.