Genotype × Environment Interaction and Stability for Grain Yield in Some Promising Rice Cultivars

Adaptability and stability of eight promising rice lines (genotypes) were determined by conducting a randomized complete blocks design with four replications at three locations (Rasht, Roudsar and Talesh) and in three consecutive years (2001-2003). The agro-morphological traits such as grain yield, panicle number, 100-grain weight, plant height, panicle length, days to 50% flowering and grain quality characters such as amylose content, gelatinization temperature, gel consistency and milling recovery were measured adopting standard methods. Analysis of variance based on each location revealed that the cultivars were significantly different for all the observed traits. However, for panicle length (in Rasht) and milling recovery (in Roudsar) the differences were not statistically significant. Combined analysis over three locations and years revealed highly significant differences for all characters among the eight genotypes studied. The differences of locations were significant only for hundred grain weight. Highly significant F were observed for genotype × location × year interactions for traits such as grain yield, 100 grain weight, plant height and panicle length. Overall, mean yield comparison over three locations and three years showed that the lines 837, 838, 840, and 841 were the highest yielding among genotypes ranging from 5.85 to 5.94 t/ha. Stability analysis revealed that the cultivars 838, 840 and 841 are the most stable genotypes, showing lower coefficient of variation and also within location mean square. However, lines 840 and 841 having superior grain quality are comparable with Iranian traditional land races and are recommended for immediate release in Giulan province. These two stable high yielding cultivars are also resistant to blast disease.