GENETIC VARIABILITY ANALYSIS OF CHOSEN NIGERIAN SOYBEAN (GLYCINE MAX (L) MERRIL) ACCESSIONS

Abstract:

Soybean, a crucial leguminous seed crop renowned for its prized protein and oil content, holds significance in food, feed, and industrial sectors. Amplifying soybean cultivation could play a pivotal role in mitigating food insecurity, with genetic advancements promising substantial benefits to humanity. Genetic variability serves as the cornerstone of crop enhancement, facilitating extensive trait selection. The amalgamation of morphological and molecular techniques for trait selection heightens the prevalence of favorable alleles, thus enriching breeding programs across crops. This study delves into the genetic variability within soybean, aiming to assess genetic diversity in a selection of accessions for effective trait selection, utilization, and enhancement.

A collection of twenty soybean accessions sourced from the gene bank of the International Institute of Tropical Agriculture (IITA), Ibadan, underwent evaluation utilizing a randomized complete block design (RCBD) with three replicates. The evaluation encompassed agro-morphological parameters. Subsequent assessment of genetic diversity entailed the deployment of simple sequence repeat (SSR) markers, along with pollen parameters for accession characterization. Notably, a significant (P < 0.05) spectrum of variability emerged across all evaluated morphological attributes, with specific accessions manifesting preference for distinct trait(s). For instance, TGX–2016-4E accession exhibited the tallest plant height (46.17 cm), while TGX–1485-1D showcased the highest pod production (216.47), and TGX-2027-1E yielded the greatest seed yield per plant (1167.67).

The study unveiled considerable variability even in qualitative traits like leaflet size, leaflet shape, pubescence, pubescence density, pubescence color, pubescence type, cotyledon color, corolla color, seed shattering, and mature pod color. Phenotypic coefficient of variation exceeded genotypic coefficient of variation for all traits. Notably, moderate to high broad-sense heritability spanning 32.99% to 95.37% was ascertained, accompanied by genetic advances as a percentage mean ranging from 0.16% to 58.89%. Most accessions demonstrated robust pollen viability, reaching up to 84.60%, with the exception of TGX-2010-11F recording 26.70%.

The molecular diversity exploration incorporated 11 selected genotypes from the initial pool of twenty accessions, employing simple sequence repeat (SSR) DNA markers. This endeavor produced base pairs ranging from 150 to 320, facilitated by six primers. Genetic similarity within the genotypes spanned 0.17 to 4.09, revealing an average gene diversity of 0.28. The clustered dendrogram of the 11 genotypes unveiled two primary clades, prominently TGX-1987-62F and TGX-2011-6F. The substantial genetic variability observed in both morphological and molecular realms, coupled with high heritability and genetic advanceing several parameters, underscores the potential of these genotypes for targeted trait selection and utilization, thereby fostering crop enhancement.

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