Submitted to: Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2004
Publication Date: 11/25/2005
Citation: Mulema, J.K., Olanya, O.M., Adipala, E., Wagoire, W.W. 2005. Stability of late blight resistance in population B potato clones. Potato Research. 47: 11-24 Interpretive Summary: Resistance management of potato late blight is one of the most economical methods for late blight control in low input farming systems. The stability of late blight resistance is important for predicting variety performance at various cropping locations. Population B selections with quantitative resistance were evaluated for their stability to late blight resistance in replicated field experiments at many testing locations. The additive main effects and multiplicative interaction statistical model was used in determining stability parameters. The stability statistics generally identified superior and stable late blight resistant genotypes. Selective deployment of those genotypes can enhance effective late blight control and subsequently minimize economic loss.
Technical Abstract: Potato late blight is a significant production constraint in East Africa. The current emphasis in late blight management in the East African tropics has been the development of potato varieties with durable resistance to late blight disease. Seven promising potato clones from population B with quantitative resistance (no R-genes), two advanced clones from population A (with R-genes) and three variety checks were grown for three cropping seasons in multiple environments in order to determine their performance and stability to late blight resistance. Disease occurrence was detected in all cropping seasons. The analysis of variance of disease data (AUDPC) for environments, genotypes and genotype x environment (G x E) interactions were highly significant (P<0.001) indicating the differential response of the genotypes and the need for stability analysis. The Additive Main Effects and Multiplicative Interaction (AMMI) statistical model, showed that the most stable genotypes were 392127.256, 381471.18, 387121.4 (resistant) and 391049.255 (susceptible to late blight). Within environments, the ranking of genotypes was not consistent. However, Kabale was ranked as the most susceptible genotype (43.9%) while Rutuku was ranked the most resistant (11.7%). Four of the testing sites were the most stable environments. The stability statistics generally identified superior and stable late blight resistant genotypes for various locations of Uganda. Selective deployment of resistant and stable varieties is critical in minimizing economic losses.