GENETIC DIVERSITY AND TRAIT ASSOCIATIONS IN SORGHUM (Sorghum bicolor L. Moench) GERMPLASM UNDER RAINFED CONDITIONS

Abstract

Sorghum is a key cereal crop in Sub-Saharan Africa that is used as food, fodder, and biofuel. This study evaluated the genetic diversity and trait associations among sorghum accessions collected from the Nigeria Southern Guinea Savanna (SGS). A total of 160 accessions were initially collected from farmers’ fields and preliminarily screened based on distinct morphological traits. Of these, 20 distinct accessions were selected and evaluated in 6 SGS environments with 2 improved varieties under rainfed conditions in the 2021 and 2022 growing seasons. The results revealed moderate to high genotypic and phenotypic coefficients of variation and high heritability estimates (66.83–97.75%) for most traits, indicating that the accessions harbour valuable genetic diversity and that selection among them would be effective for breeding purposes. Accessions LR55 (1323 kg ha⁻¹), DR25 (1293 kg ha⁻¹), and LR2 (1226 kg ha⁻¹) were selected for their high yield and stability, and LR2, DR18, and DR15 were selected through a Genotype by Yield*Trait biplot approach for their optimal combination of yield and nutritional quality traits. These accessions are promising candidates for both direct cultivation and as elite genetic resources in sorghum improvement programs. Significant positive and negative correlations were observed among agronomic and nutritional traits, but most yield-related traits showed non-significant correlations with nutritional quality traits. Leaf width, percentage of grain coverage, number of panicles harvested, 100-seed weight, and 1000-seed weight were identified as reliable selection indices for yield improvement based on their high heritability and strong positive correlation with grain yield.