MORPHOLOGICAL AND MOLECULAR CHARACTERIZATION OF FIFTY SORGHUM (SORGHUM BICOLOR L. MOENCH) ACCESSIONS COLLECTED FROM SOUTHERN NIGERIA

Abstract

Sorghum is a diploid, self-pollinated crop with considerable diversity. Its genetic diversity could be exploited as a possibility for improving its productivity and studying species to know if they have similar genes. Southern Nigeria consists of several uncharacterized sorghum accessions which were grown mainly for food and feed. Thus, the region contributed very little to the total sorghum produced in Nigeria. Fifty sorghum accessions collected from fourteen southern States were grown in Ogbomoso (2018 and 2019), Ishiagu (2018 and 2019) and Akure (2019) with the aim of characterizing them using morphological and molecular markers. The field experiment was arranged in a randomized complete block design with three replications. Agronomic data were collected on 22 parameters which were subjected to Analysis of variance, Component of variance, Character association, Principal component analysis (PCA), Single linkage cluster analysis (SLCA), and GGE biplot analysis. Similarly, DNA of the 50 accessions were extracted for molecular analysis using five primer pairs. Result from the morphological characterization showed different levels of variation among the accessions for all the qualitative characters. Significant (p≤0.01) variations were recorded across the environments, genotype, and Genotype by Environment Interaction (GEI) for all the traits except leaf length and leaf width. High heritability with high genetic advance estimates recorded for plant height (89.76; 31.73%), panicle width (72.95; 38.07%), panicle weight (66.50; 41.93%), panicle length (92.56; 44.94%), days to 50% anthesis (94.52; 21.76%), number of leaves (81.38; 23.94%), number of nodes (77.05; 26.78%), leaf length (85.09; 21.26%) and days to 50% heading (94.89 and 23.23%) implied an opportunity for selection of the traits. Similarly, significant phenotypic and genotypic correlations occurred among most of the characters. PCA and SLCA were employed to analyze the magnitude and pattern of diversity among the accessions. The first six Principal components jointly accounted for 90.69% of the total variance. Furthermore, SLCA grouped the accessions into seven clusters based on their level of similarity. With a total of 36 alleles, a Polymorphic information content (PIC) of 0.27 (XTXP 62) to 0.71 (XTXP 057), an average genetic diversity of 0.57 was recorded from the molecular analysis. Two main clusters were detected from the UPGMA dendrogram; the first consisted of 49 accessions with three subclusters while the second consisted only one accession. Based on the present results, the fifty accessions were consistent for qualitative characters, with high genetic diversity and heterogeneity. Plant height, panicle weight, panicle length and days to 50% heading are the most discriminating characters that contributed to variation. Positive correlation between the growth, flowering and maturation traits could be used as selection criteria for high grain weight in sorghum. Accessions G5, G48, G39, G9 and G26 are the most distinct and can be selected for hybridization. PIC value obtained showed that the primers are polymorphic suggesting a high level of diversity among the accession. Primers XTXP057 and XTXP56 are the most informative for characterizing the 50 accessions. Thus, the use of more Simple Sequence Repeats primer in combination with morphological markers for effective characterization in the future is recommended.