GENETIC VARIABILITY ANDASSOCIATION AMONG BULB YIELD AND YIELD RELATED TRAITS OF GARLIC (Allium sativum L.) GENOTYPES AT BISHOFTU AGRICULTURAL RESEARCH CENTER, ETHIOPIA

Abstract

Assessment of genetic variability in crop species is one of the major activities of plant breeding which helps to design breeding methods and/or selection of genotypes for further evaluation to meet the diversified goals. Therefore, this field experiment was conducted to assess the genetic variability in garlic genotypes, to determine association among traits and estimate the direct and indirect effects of traits on bulb yield. The field evaluation of 34 genotypes and 2 released varieties (G-HL and Chefe) was conducted in 6x6 Triple Lattice Design at Bishoftu Agricultural Research Center during January 2020 to May 2020. Results of analysis of variance revealed the presence of significant differences among genotypes for 18 quantitative traits. The variation observed among genotypes for bulb yield ranged from 43.80 to 147.20 kg ha-1. The six genotypes (G-32-1/94, G-092-3/95, G-36-2/94, G-110/06, G-032/02, and G-040/06 had mean performances higher than the highest performing check variety (G-HL=99.5Kg ha-1). Phenotypic (PCV) and genotypic (GCV) coefficient of variations ranged from 4.22% (days to maturity) to 37.83% (BYPL) and 2.62% (harvest index) to 32.54% (Clove diameter), respectively. Heritability (H2b) in broad sense and genetic advance as percent of mean (GAM) ranged between 9.89% (harvest index) and 91.39% (bulb yield per hectare) and 1.70% (harvest index) and 63.11% (clove diameter), respectively. High H2b estimates coupled with high GAM for bulb yield per hectare, biological yield per plant, leaves width, number of leaves per plant, neck diameter, clove length, clove diameter and clove weight suggested the higher chance of improving these traits through selection of genotypes for high mean performance.Bulb yield per plot was highly significant and positively correlated with all characters except, days to emergence,days to maturity, leaves length, clove diameter and bulb yield per hectare both at genotypic and phenotypic levels. As per the path coefficient analysis biological yield per plant showed high positive phenotypic direct high effect on bulb yield whereas positive phenotypic direct effect observed for characters leaves width, harvest index, bulb weight andclove weight. Similarly,the path analysis based on genotypic correlation in the present study has shown that breeding for leaves width, bulb length, number of leaves per plant, clove length and clove weight traitsare effective through selection for biological yield per plant. The first four principal component axes (PCA) with Eigenvalues >1 accounted for 79.67% variation of genotypes. The genotypes were grouped into three distinct clusters of which Cluster II, I and III consisted of 19(52.78%), 12(33.33%) and 5(13.89%)genotypes, respectively. Cluster I and Cluster II consisted of two released varieties (G/HL and Chefe) genotypes, respectively. Generally, the results of this study showed the presence of variations among genotypes for agro-morphology traits with a wide range of genetic distances that could allow selection and/or hybridization of genotypes after the results of this study are confirmed across locations and over the years.