Genotype by Environment Interaction and Yield Stability of Potato Cultivars under Tropical Conditions

Potato (Solanum tuberosum ssp. tuberosum) cultivars grown under tropical conditions exhibit comparatively poor yields compared to the temperate conditions, hence, there is need for stable cultivars with greater yields. The interactions of four cultivars with ten environments for 2 years under All India Coordinated Research Project (Potato) across the country for 2 harvesting stage (75 and 90 DAP) revealed that the cultivars were significantly different among themselves for Total Yield (TY) and Marketable Yield (MY) harvested at 75 and 90 DAP at seven and eight environments, respectively. The pooled analysis showed a significant difference for cultivar and environmental main effects for all traits, indicating the existence of cultivars genetic variability justified from the heterogeneity of environments. The significant effect of G×E interaction for TY and MY at 90 DAP, and a non significance for the same traits at 75 DAP clearly indicated that the prevailing environments during early crop stage were uniform as compared to its later harvesting stage. Partitioning of G×E interaction into linear and non linear components were highly significant for all traits, strongly suggesting the real differences in cultivars for regression over environmental means and the response of cultivars to environment was controlled genetically. The cultivar K. Pukhraj was proven as early bulking and stable cultivar for TY and MY at 75 DAP and predictable in nature, as against K. Khyati which was stable cultivar for TY and MY at 90 DAP across growing environments. Hence, K. Khyati, which recorded the highest TY (27.45 t ha^-1) and MY (25.24 t ha^-1) for harvesting at 75 DAP, and TY (31.28 t ha^-1) and MY (28.19 t ha^-1) at 90 DAP, can be recommended for tropical conditions.