Investigating the relationships between grain yield and quality related traits in some promising lines of rice (Oryza sativa L.)

Investigating the relationship between the studied traits has an important role in plant breeding and can identify and introduce appropriate selection indices for population breeding. In this study, the relationships between yield related traits and grain quality of 62 rice promising lines were evaluated. The experiment was conducted in a randomized complete block design with three replications at Rice Research Institute of Iran, Rashr, Iran, in 2020. Estimating the phenotypic correlation coefficients between traits showed that there was a positive and significant correlation between grain yield and 1000-grain weight, number of filled grains per panicle, number of panicles per plant and day to 50% flowering, and negative and significant correlation with plant height and panicle length. Narrow-sense heritability of the measured traits ranged from about 32% for number of filled grains per panicle to 49% for flag leaf width and grain length. Path analysis between grain yield and the other studied traits showed that 1000-grain weight, number of panicles per plant and number of filled grains per panicle had a positive and direct effect on grain yield. Factor analysis showed that four main and independent factors that explained 78.50% of the total variance were the latent factors affecting the studied traits. These factors were named as grain yield and plant type, grain appearance characteristics, milling efficiency and fertility rate factors, respectively. Cluster analysis using the Ward’s minimum variance method grouped the studied lines into three separate clusters and the first cluster with 13 lines had the higher grain yield, number of panicles per plant, number of filled grains per panicle and fertility percentage than the other clusters. This cluster had also moderate amylose content and higher values for grain length and cooked rice length related to other clusters. Therefore, it seems that the lines of this group can be introduced as new high yield and qualitative cultivars after evaluation in multi-regional experiments.