Authors: Lawal IT, Akintunde FC, Alake CO, Porbeni JBO.
Despite soybean high economic value in many countries of Africa, the crop has received little attention with respect to genetic diversity and yield stability. Hence, inadequate production of soybean in Nigeria occasioned by lack of high-yielding improved varieties and unstable yields among others need to be investigated. This study assessed the diversity and yield stability in soybean genotypes for appropriate selection for improvement programme. Twenty- four soybean genotypes obtained from the International Institute of Tropical Agriculture, Ibadan were grown at the Teaching and Research Farms of the Federal University of Agriculture, Abeokuta (Latitude 7°15 ?N and Longitude 3°25 ?E), Institute of Agriculture Research and Training, Ibadan, Oyo State (Latitude 7°23 ?N and Longitude 3°27 ?E) and Lagos State Polytechnic, Ikorodu, Lagos State (Latitude 6°37 ?N and Longitude 3°30 ?E). Plantings were done in Abeokuta in May, 2017, Lagos and Ibadan in May and June, 2018, respectively. The experiments were laid out in a Randomized Complete Block Design with three replicates across the three locations. Data collected were subjected to Statistical Analysis. Results showed that the genotypes evaluated differed significantly (p<0.05) for agronomic characters, indicating the possibility of selecting soybean genotypes with superior seed yield characters. Dendrogram generated from Ward Linkage Clustering grouped the twenty-four soybean genotypes into five clusters, indicating genetic similarity and diversity among the genotypes. The AMMI analysis revealed that the total variance in soybean grain yield accounted for, by genotypes (G), environment (E) and genotype x environment interaction, with values of 43.00, 28.18 and 28.81%, respectively. Genotype TGx2004-10F was unstable across environments, but had high seed yield in Lagos. Genotype Selection Index (GSI), which combines both AMMI Stability Value and mean seed yield, revealed genotypes TGx1990-3F, TGx2010-11F, TGx1990-80F, TGx1991- 10F and TGx1987-62F were stable with higher seed yield across the tested environments. These genotypes are therefore suitable for cultivation across the environments and are thus recommended.
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