Genotype x environment interactions of hybrid and varietal rice cultivars for grain yield and milling quality
The study of genotype x environment interaction is critical for accurate cultivar evaluation in large multi-environment trials. Cultivars that exhibit high levels of mean performance and stability across a wide range of environmental conditions are desirable for rice production. Pure-line varietal and hybrid rice cultivars are commercially produced in the U.S.; however, little research has been conducted comparing their stability for grain yield and milling quality. In this study, 15 hybrid and varietal cultivars were grown in 10 environments from 2005 to 2007 to determine the performance and stability of rough rice yield, whole milled rice percentages, and whole-grain rice yield. Stability was analyzed using the coefficient of variation, Shukla's Stability Variance statistic with environment means as a covariate, and the Cultivar Superiority Measure. The hybrid rice cultivars XP723 and CLXL730 were ideal for high and stable rough rice and whole-grain rice yields on the basis of the cultivar superiority measure; however, for whole milled rice percentage alone, they were among the least desirable cultivars. Among the varietal cultivars, Catahoula and Jupiter were ideal cultivar selections for high and stable whole-grain rice yields. The results of this study indicate that the stability and performance of hybrid and varietal cultivars differ according to the trait of interest.