Drought response in field grown potatoes and the interactions between canopy growth and yield

Potato is an important food crop with high yields. However when exposed to drought it suffers major yield losses. Considering its global importance and the increasing incidence of drought due to climate change, research toward drought tolerance in potato remains imperative. We have studied a set of 103 commercial cultivars representing the genetic diversity in the European potato market. The cultivars were grown in different field locations in three subsequent years (2013-2015). Our aim was to understand how different field drought regimes affect canopy growth in potato, and how these effects translate to tuber yield. The field environmental conditions were monitored, and pictures of canopy ground cover during the growing season were taken. Canopy growth parameters were extracted by an iterative method using the beta sigmoid growth function to model canopy growth. At harvest, tuber yield was scored and tuber size was graded. The GGE (Genotype and Genotype-by-Environment) bi-plot and Finlay Wilkinson's Regression were used to investigate Genotype x Environment interactions. We observed that the timing of the drought occurrence differentially affected canopy growth and tuber yield. Under drought stress, fast attainment of exponential growth and maximum canopy cover had negative effects on tuber formation and tuber bulking. Growth rate, maximum canopy cover, and area under the canopy curve (photosynthetic capacity over the growth season) were more important for tuber bulking than they were for tuber formation under drought stress. Cultivars with high yield were identified as potential material for improvement to drought tolerance. These findings will contribute to the breeding for drought-tolerant potato amidst the threats of climate change.