Genetic Variability and Character Association in Upland Rice (Oryza sativa L.) Genotypes, Southwestern Ethiopia

Abstract

This study aimed to estimate the genetic variability of 36 upland rice genotypes for yield and its components, and determine trait association among morphological traits. The field experiment was conducted using simple lattice design at two locations (Guraferda and Gojeb) during 2016 main cropping season. Analysis of variance for individual locations revealed significant differences (P≤0.05) among genotypes for most of the studied traits at Guraferda, however number of fertile tillers per plant, number of unfilled grains per panicle, non-fertile tillers per plant, panicle length, thousand grain weight and biological yield were found being non-significant. Similarly, the genotypes showed significant difference (P≤0.05) for plant height, number of filled grain per panicle, days to maturity, number of primary branches per panicle and grain yield however the remaining traits were showed non-significant difference among genotypes at Gojeb. Combined analysis of variance over the two locations revealed significant differences (P≤0.05) among the genotypes for most of the studied traits, while genotype x location interactions showed significant differences for the traits, total number of tillers per plant, plant height, days to 50% heading, days to maturity and grain yield. The mean over the two locations showed, wide ranges for number of filled grains per panicle (24-123), days to 50% heading (50-83) and grain yield (15-34 q/ha). The genotypic coefficient of variation ranged from 2.3% for plant height to 19.5% for number of filled grains per panicle, and phenotypic coefficient of variation (PCV) ranged from 4.0% for panicle length to 20.2% for filled grains per panicle. High broad sense heritability (H 2 B) estimates were obtained for number of filled grains per panicle (93.3%) and days to 50% heading (61.6%); while low H 2 B value was found for plant height (20.1%), number of primary branches per panicle (15.1%) and grain yield (14.4%). The estimates of genetic advance as the percentage of the mean (GAM) ranged from 2.1% for plant height to 38.8% for number of filled grains per panicle. High H 2 B coupled with high GAM were obtained for number of filled grains per panicle, which indicates that this trait can be effectively improved through selection. Grain yield showed significant and positive genotypic correlation with 1000-grain weight, days to 50% heading, days to maturity and harvest index. Similarly, it showed significant and positive phenotypic correlation with panicle length, number of filled grains per panicle, 1000-grain weight, fertile tillers per plant and number of primary branches per panicle. Path coefficient analysis at genotypic level revealed high and positive direct effect of days to heading (0.7), 1000-grain weight (0.6), days to maturity (0.3) and harvest index (0.2). The detected positive correlation indicated that, increases in the value of one trait results in increasing the correlated traits. Keywords: Broad sense heritability, Upland rice, Variability, DOI : 10.7176/JBAH/9-3-02