Quantitative studies for investigating variation and its effect on heterosis of rice

An important step in plant breeding programs is identification of parents that are genetically distant from each other, to find crossing combinations with better prospects of hybrid vigor. The potential of identifying genetically distant parents depends on genetic diversity of population. 58 lines of rice from diverse origins have been employed to study genetic variation in order to identify the most effective components of grain yield. Using cluster analysis, the lines were classified into three distinct classes; some of classes containing lines from different origins. Factor analysis has been conducted to identify important components of variation and contributions of traits in each factor. Based on factor analysis, 6 components were identified, explaining ~82% of observed variation. Evaluation of heterosis of crosses, whose parents were selected based on genetic distances (GD), showed that maximum heterosis was obtained for crosses containing the furthest lines. All together, our results support the idea that the level of correlation between hybrid performance and genetic divergence is depends on the germplasm used.