Genotype x Environment Interaction for Tuber Yield, Dry Matter Content and Specific Gravity in Elite Tetraploid Potato (Solanum Tuberosum L.) Genotypes

A study was conducted to determine stability of tuber yield, dry matter content and specific gravity, and the nature and magnitude of genotype x environment (G x E) interaction in elite tetraploid potato genotypes. Eleven potato genotypes including two standard checks were evaluated in the eastern part of Ethiopia at Haramaya, Langae, Kulubi, Hirna and Arberekete during 2008 and 2009 cropping seasons under rainfed condition. There were significant variations among genotypes with respect to tuber yield and dry matter content while the genotypes exhibited comparable tuber specific gravity values. Significant G x E interaction was observed for tuber yield and dry matter content and G x E mean square for tuber specific gravity was not significant indicating that G x E has negligible influence on the trait. Partitioning of the G x E interaction for both tuber yield and dry matter content indicated the presence of both linear and non-linear types of G x E interactions. None of the genotypes were found to be stable and ranked at the top for tuber yield, dry matter and specific gravity. The stability and responsiveness appeared to be specific for specific character within a single genotype. Genotype CIP-392640-528 is stable for specific gravity, average responsive for tuber dry matter content and above responsive for tuber yield. Highly significant positive correlation (r = 0.99) was obtained between specific gravity and dry matter content proving that specific gravity is a true indicator of tuber dry matter content. The observed significant G x E interaction for tuber yield and dry matter content suggests that potato breeders should give special emphasis for G x E interaction while developing stable and high yielding genotypes in terms of tuber yield and dry matter content.