Genetic variability in agronomic traits and associations in sorghum [(Sorghum bicolor (L.) Moench)] genotypes at intermediate agro-ecology sorghum growing areas of Ethiopia

The present study consists of 14 sorghum genotypes evaluated at Bako, Jimma and Mechara research centers to study genetic variability and interrelationships of traits with grain yield. The experiment was conducted by using randomized complete block design (RCBD) with three replications during 2014 and 2015 main rainy season. Data on important agronomic traits were collected. The combined analysis of variance (ANOVA) across years and locations showed highly significant differences among genotypes for all traits, indicating the presence of sufficient variability among the genotypes. Environmental coefficients of variation (ECV), genotypic coefficients of variation (GCV) and Phenotypic coefficient of variation (PCV) ranges of the study are days to 50% maturity (DM, 0.49) to number of seeds per panicle (NSPP, 6.11); DM (0.31) to PAS (16.99) and DM (1.12) to GY (20.86) in the same order. High h2BS values were observed in hundred seed weight (HSW, 76%), DS (70%), plant height (PH, 65%) and PAS (63). High value of genetic advance as a percentage of mean (GA% µ) was recorded by PAS (27.42%), PH (26.29%) and DS (20.65%) and moderate amount of GA%µ was recorded by HSW (11.78%) and HW (11.08%). High h2BS coupled with high to moderate GA%µ was reported for PH (65 and 26.29%); HSW (76 and 11.78%); PAS (63 and 27.42%) and DS (70 and 20.65%) indicating PH and HSW are controlled by additive gene action. GY had strong positive genotypic association with HW (0.99) followed by NSPP (0.96). These results suggested that any positive increase in such traits will increase the grain yield. The genotypic path analysis also showed that head weight per plot (HW, 1.96) and PH (0.55), had high and very high positive direct effect, respectively on GY indicating that these traits are the most important yield component traits. Hence, due consideration should be given to these traits while selecting promising lines. Key words: Correlation coefficient, genetic advance, heritability, path coefficient, sorghum.