Analysis of genotypic and phenotypic correlations and path coefficients in 40 genotypes of rain-fed upland rice (Oryza sativa L.) in Oyo and Ogun states regions of Nigeria

Abstract

Sustainable rice production in upland habitats depends on achieving higher yields. This study employs correlation and path coefficient analyses to identify essential trait criteria for enhancing rice yield in upland genotypes. The study included two growing seasons using 40 genotypes. Genotypic correlation analysis reveals a robust positive correlation of effective tillering with panicle number and yield. Notably, it shows significant negative correlations with 1000-grain weight and leaf width across diverse locations and cropping seasons. Additionally, the phenotypic estimates underscore a substantial positive correlation between yield and panicle number. Furthermore, the path analysis reveals that panicle number maintains a significantly positive association with yield at the 5% level of significance. Moreover, the analysis of the direct and indirect genotypic effects underscores the significance of culm number, effective tillering, and panicle number, all of which show remarkable and positive correlations with yield, achieving statistical significance at both the 5% and 1% levels. To enhance rice grain yield, a genotype must have an elevated count of pivotal traits per plant, including heightened panicle number, increased panicle length, greater culm number, elongated culm length, a greater number of effective tillers, early flowering initiation, expedited maturation, and augmented leaf length. These characteristics are pivotal determinants contributing significantly to the overall grain yield in rice cultivation and they are instrumental for sustainable rice improvement in the agro-ecology.

Keywords

• genetic diversity
• rice improvement
• yield
• yield-related traits
• genotype by environment interactions