GENETIC VARIABILITY OF SORGHUM (SORGHUM BICOLOR L.) RECOMBINANT INBRED LINES UNDER STRIGA (STRIGA HERMONTHICA (DEL.) BENTH) INFESTED AND STRIGA FREE ENVIRONMENTS
Striga hermonthica is the most important biotic agent that causes significant loss in yield and productivity of sorghum in the savannas. This study objective was to assess the levels of Striga resistance in recombinant inbred populations of sorghum. Six hundred and sixty recombinant inbred populations of sorghum (parents and checks inclusive) obtained from F4 generations of NRL-3 × SRN4841 F4 and SAMSORG 39 × WADAHMED F4 were evaluated in two Striga infested environments (Samaru and Birnin Kudu) and two Striga free environments (Samaru and Kano). Data collected on Striga characteristics, yield and yield related characteristics were subjected to statistical analyses using R statistical software. The result revealed great variability within recombinant inbred lines with the identification of eleven NRL-3 × SRN4841 F4 and seven SAMSORG 49 × WADAHMED F4 recombinant inbred populations having zero striga count indicating striga resistance. Large differences between phenotypic and genotypic coefficients of variation were obtained for striga characters and ranged from 0.00% to 68.53% for NRL-3 x SRN4841 F4 and 25.97% to 91.10% for SAMSORG 49 × WADAHMED F4 suggesting that environment contributed to the expression of striga characteristics. Low (< 30%) broad-sense heritability for striga count, striga vigour, ASNPC and ASVPC indicate small genetic variation implying that genetic gain after selection will be low due to the combined effects of genetic and environmental variations. Therefore, the highly Striga resistant recombinant inbred lines can readily be exploited in sorghum improvement as sources of favourable alleles to improve locally adapted germplasm.
Keywords: genotype x environment, recombinant, resistance, sorghum, striga, variation
*Correspondence: victor.musa.86@gmail.com, 08065462933
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