ADAPTABILITY OF SIFT POTATO GENOTYPES IN DIFFERENT AGRO- ECOLOGIES OF UGANDA

The effect of genotype by environment interaction (G x E) on fresh tuber yield of nine Standard International Field Trials (SIFT) potato (Solarium tuberosum L.) genotypes and Kisoro, a local variety, was studied in Uganda using additive main effects and multiplicative interaction (AMMI) model 3. Results indicated that the proportion of the environmental variation was much larger than the proportion due to genotypes and the proportion due to G x E interaction was also larger than the genotype main effects. Genotypes (G), environments (E) and the G x E interactions accounted for 8.43, 57.13 and 34.44% of the treatment sums of squares, respectively. AMMI and the biplot identified genotypes384866.5,381381.13,389746.2, Kisoro and386209.10 as adapted to four environments. Test genotypes 389746.2, Robijn and 381381.13 were the most stable and had higher yields ( 19 t ha^-1) than all genotypes except Torridon, which was also very unstable and specifically adapted to one environment (Kalengyere 2B). Kalengyere IB and Wanale 2A were identified as similar environments.