Genetic Variability and Character Association Analysis for Yield and Its Related Traits in Rain Fed Lowland Rice (<i>Oryza sativa </i>L.)<i> </i>Genotypes at Teppi and Fogera, Ethiopia

In Ethiopia, rice variety development started very recently and is mainly dependent on the introduction breeding materials in which characterization and understanding of the genetic variability of genotypes is the critical step. Knowledge of the extent of genetic variability and interrelationships of yield and yield components is pre-request for designing an effective selection-based rice improvement programs for evolving high yielding rice genotypes. Therefore, this study was carried out with all objectives of assessing genetic variation for yield and yield related traits in lowland rice genotypes. Thirty-six selected lowland rice genotypes were evaluated in simple lattice design with two replications during 2017 cropping season and data on 15 quantitative morphological traits were collected and subjected to various statistical analysis. Combined analysis of variance across location revealed significant location, genotype and genotype × location interaction effects for the traits evaluated at p ≤0.01. The phenotypic coefficient of variation was high for un fertile tiller per plant (88.16 %), followed by infertile grain per panicle (50.66%), and grain yield (21.57%), and the genotypic coefficient of variation was high for un fertile tiller per plant (50.38 %), followed by infertile grain per panicle (27.22%), and culm length (17.7%). The estimate of broad sense heritability ranges from 15.2% for biological yield to 91.5% for plant height. The expected genetic advance as present of mean varied from 5.42% for biological yield to 59.3% for unfertile tiller per plant. Phenotypic and genotypic correlation revealed grain yield had a a significant and positive association with primary branches per panicle (rp=0.4, rg=0.7), fertile grain per panicle (rp=0.5, rg=0.72) and harvest index (rp=0.76, rg=0.73) at both genotypic and phenotypic. Path coefficient analysis of grain yield revealed that harvest index, total tiller per plant and thousand grain weights showed positive phenotypic direct effect. A Positive direct effect was found for total tiller per plant, harvest index and biological yield at genotypic level. The present study indicated sufficient genetic variability for the characters studied in rain fed low land rice genotype, which will create opportunity for future improvement. To have full scale data, further study at various locations and years with the help of molecular techniques should be done.