Genetic variability in sorghum (Sorghum bicolor (L.) Moench) genotypes for anthracnose (Colletotrichum sublineolum) resistance, growth and yield related traits at Arba Minch and Derashe districts in southern Ethiopia

Abstract

Anthracnose disease caused by Colletotrichum sublineolum is a major constraint that limits the production and productivity of sorghum in Ethiopia as well as in other countries. This study was carried out at Arba Minch and Derashe districts during the 2018 cropping season, March to August. The objective of the study was to identify the host resistance for anthracnose management and estimate the genetic variability in terms of resistance to anthracnose, growth, and yield potentials of sorghum. The treatments used in the study were 14 sorghum genotypes and laid in a randomized complete block design with three replications. The results from this study showed that Arghiti, Dekeba, and 76TI#23 were found resistant, while Kolamulato-W, Konso-R, Gambella, and Seredo were highly susceptible to anthracnose. The lowest (0.25 t ha-1) grain yield was recorded from all landraces, whereas the highest (3.22 t ha-1) grain yield was obtained from the genotype Melkam. The high phenotypic and genotypic variances were figured out for the study parameters, while the environmental variance was lower than the genotypic and phenotypic variances. Low to high genotypic (21.40 to 57.94%) and phenotypic (22.66 to 95.21%) coefficients of variations were computed for the study parameters. The high heritability of 59.30 to 99.63% and the genetic advance in percent means of 20.21 to 63.10% were calculated for the study parameters. The disease parameters, like disease severity and area under disease progress curve (AUDPC) (rg = 0.725), showed a strong and positive association of genotypic coefficients correlations. Also, strong and negative genotypic coefficients of correlations were observed between the disease and traits studied, like AUDPC and grain yield (rg = -0.561). The dendrogram of the sorghum genotypes using the Unweighted Pair-Group Method with Arithmetic means analysis and Euclidean distances separated the genotypes into three clusters. The result from this study revealed that the sorghum genotypes noticeably varied in resistance to anthracnose as well as growth and yield potential. Therefore, sorghum producers could beneficially produce resistant, moderately resistant, and high-yielding genotypes with minimum integrated management efforts against the anthracnose. Moreover, the genetic variability and the high heritability together with, and the high genetic gain of the characters, suggest the potential of bettering the genotype for disease resistance and high yield potential through selection.