Genetic Gain of Tuber Yield and Late Blight [Phytophthora infestans (Mont.) de Bary] Resistance in Potato (Solanum tuberosum L.) Varieties in Ethiopia

Potato variety development for tuber yield and disease resistance has been conducted in Ethiopia uninterrupted since the first variety was released in 1987. However, there is an information gap about the genetic progress made over time which needs a periodic evaluation of the varieties. This study was conducted to determine the rate and magnitude of progress in tuber yield and resistance to late blight of 16 potato varieties released between 1987 and 2011 and two farmers’ varieties. The varieties were planted in randomized complete block design with three replications at Haramaya, Hirna and Arberkete in eastern Ethiopia. The analysis of variance for each location revealed the presence of significant differences among the varieties in tuber yield and resistance to late blight. The mean total and marketable tuber yields increased over locations at the rate of 0.14 and 0.18 t ha-1, respectively, and late blight severity score reduced at the rate of 0.31% per year over the 25 years of variety development in the country. However, the increased tuber yield varied across the locations. Late blight severity score explained total tuber yield variations between 31.39 to 80.1% across the locations. It could be concluded that most of the varieties became susceptible to late blight in favourable environments for the pathogen at Haramaya and only a few varieties (Bulle, Bubu, Belete and Gera) performed better for tuber yield and late blight resistance across all locations. What is more, the varieties released recently by different centres showed higher disease severity scores than the older varieties