GENETIC VARIABILITY AND ASSOCIATION AMONG AGRO MORPHOLOGICAL AND QUALITY TRAITS IN GROUNDNUT (Arachis hypogaea L.) GENOTYPES IN EASTERN ETHIOPIA

Abstract

It is imperative to study the level of genetic variability available in the existing groundnut genotypes due to the fact that, the aim of groundnut breeding programs across the world is to develop new varieties that meet the needs of growers, processors, consumers, and overall market demands. The present study was carried out to assess the extent of genetic variability among groundnut genotypes for agro-morphological and quality traits and to estimate association of traits and determine direct and indirect effects of the traits on kernel and oil yields. Thirty-six groundnut genotypes were evaluated in a 6 x 6 simple lattice design during 2021 post-rainy season under irrigation at Dire Dawa, the research station of Haramaya university, Ethiopia. Data were collected on kernel yield and other morphological traits, oil content and oil yield. Analysis of variance revealed highly significant (p<0.01) differences for most of the assessed traits, except for number of seeds per pod and oil contents. Genotypes exhibited significant differnces for kernel yield (KY) with the range between 1308.8 kg ha-1 to 3954.8 kg ha-1 with over all mean value of 2387.71 kg ha-1 . The high oil yield (OY) was recored for Gv12 (1.90 t ha-1 ),followed by Gv30 (1.82 t ha-1 ). High PCV and GCV values were observed for KY, dry pod yield (DPY), biomass yield (BY), harvest index (HI) and OY. The values of broad sense heritability ranged from 97.87% for grain filling period (GFP) to 62.39% for harvest index (HI) and genetic advance as percent of mean (GAM ) ranged from 60.19% for BY to 5.60% for days to maturity (DTM). KY exhibited positive and significant (p<0.05) phenotypic and genotypic correlations with other yield contributing traits and OY. Similarly, OY revealed positive and significant correlations with other traits both at phenotypic and genotypic levels. Path analysis resulted, the highest (0.771) positive genotypic and phenotypic (0.715) direct effect on KY was exerted by DPY and the lowest (0.025) and (0.004) were NPP and plant height (PH). KY exerted the highest direct effects (0.968) on OY, while harvest index (0.009) exerted the lowest positive and direct effect at phenotypic level. The highest direct and positive effect on OY was recorded for KY (0.918) at genotypic level. In this study,the first six Principal Components Analysis (PCA) found to be significant and accounted for 74.51% of the total variation. Those 36 genotypes were grouped into six major clusters and the dendrogram showed that cluster I, II, III, IV, V and VI included 6, 9, 8, 5, 7 and 1 numbers of genotypes in that order. Euclidean distance ranged from 2.45 to 8.54 with the mean, standard deviation and coefficient of variation of 5.44, 1.17 and 21.56%, respectively. Based on the result of the current study, genotypes, Gv12, Gv30, Gv19, Gv34, Gv6 and Gv31 are high in kernel and oil yields. Therefore, these genotypes are recommended as ideal candidates for further breeding and variety developnment. Similarly, there were variations of genetic distances among genotypes, Gv17 and Gv28, Gv3 and Gv23, Gv3 and Gv30, Gv15 and Gv17, Gv22 and Gv28, and Gv3 and Gv34 which could be exploited through hybridization for cutivar development in groundnut breeding programs in Ethiopia