Aboveground Characteristics, Yield Potential and Drought Tolerance in “Konyu” Potato Cultivars with Large Root Mass

Abstract

To improve drought tolerance of potato, we bred four cultivars with large root mass and registered them as Konyu-1 to Konyu-4 in 2007. In this paper, we present the yield performance and the related aboveground characteristics of three Konyu cultivars and cv. Konafubuki (small root mass, one of the parents of these Konyu cultivars) in irrigated and droughted fields for 3 years. Consistent with our previous reports, we observed that the yield reduction in droughted fields relative to irrigated fields was less in Konyu cultivars than in Konafubuki. Konyu-2 showed the highest yield in both fields in all three experimental years. Konyu-2 and Konafubuki had a relatively high harvest index (HI) as a result of lower dry weight partitioning to the shoot regardless of water treatment. This characteristic contributed to the higher yield in the irrigated field in both cultivars compared with the other cultivars. In addition, Konyu-2 had a higher leaf/stem ratio coupled with a lower number of branches than the other cultivars. In the year of the most severe drought, the leaf area index remained below 3 (optimum value for intercept radiation) in Konafubuki, but not in Konyu-2 because of its high leaf/stem ratio. The present results suggest that in addition to large root mass, high HI coupled with high leaf/stem ratio with low number of branches may contribute to achieve high and stable yields in drought prone environments.