Abstract:
The lowland areas of Ethiopia have considerable potential for increased oil crop production including groundnut. In Benishangul Gumuz Region, groundnut is cultivated in various zones and woredas under rainfed condition. However, due to insufficient improved groundnut varieties found in the region the productivity was low. Testing genotypes for the presence of variations and generation of genetic information is the first step in plant breeding to develop varieties for the targeted area of production. Keeping these in account the current study was conducted with the objectives of determining the genetic variability and trait association and their direct and indirect effects on yield and yield related traits of groundnut genotypes at Assosa and Kamashi zones, Western Ethiopia. Twenty five groundnut genotypes were evaluated in 5 x 5 triple lattice designs. Data were recorded for 16 traits and subjected to ANOVA using SAS software. Further genetic analyses were conducted as per the formula suggested by biometricians. Analyses of variance showed mean square due to genotypes were highly significant (p 0.01) for all traits studied except seeds pod-1 at both locations. After pooled analysis, genotype effects were highly significant, while, the mean squares due to G x L interaction were highly significant for primary branches plant-1, dry pod yield and grain yield hectare-1. The results revealed wide range of variability for almost all traits at both locations. The mean dry pod yield and grain yield hectare-1 varied significantly among the genotypes with a range of 800.4 - 2348.1 kg and 529.0 - 1743.5 kg at Assosa, and 1676 - 3524 and 1128 - 2859 kg, at Kamashi, respectively. The overall mean was higher for both dry pod yield and grain yield per hectare at Kamashi. This may be attributed to the soil fertility and agro-ecology of the area. Phenotypic coefficient of variation was higher than the genotypic coefficient of variation for all the traits studied at both locations. High heritability value coupled with high genetic advance as percent of mean was observed for primary branches plant-1, 100-seed weight, dry pod yield and grain yield hectare-1at Assosa and Kamashi. This suggested the importance of additive genetic variance and improvement of these characters could be made by simple phenotypic selection. The correlation and path coefficient analysis indicated that dry pod yield hectare-1showed positive and strong correlation with grain yield also exercised the highest positive phenotypic and genotypic direct effect at both locations and combined of the two locations. The trait will be useful for direct selection to increase grain yield. Therefore, the current study revealed the presence of considerable variability for most of the traits studied and differences in the performance of the genotypes as there were significant differences among genotypes. These indicated that there is a good opportunity to improve grain yield using the tested genotypes in groundnut breeding programs. Emphasis should be given for dry pod yield hectare-1, primary branches plant-1, pods plant-1 and 100-seed weight to enhance grain yield production.