Influence of heat stress on dry matter production and photo-assimilate partitioning by four potato clones

Partitioning patterns of14C labeled assimilates were studied to determine their relationship to dry matter accumulation and distribution in four potato clones (Desiree, DTO-28, LT-1 and Russet Burbank). Plants placed in growth chambers at 35/25 C day/night temperature and 12-hour photo-period two weeks after tuber initiation were compared with plants grown continuously at 25/12 C. Two weeks after temperature treatments were begun, the most recently expanded leaf was labeled with14CO2 for 30 minutes, and plants were harvested 20 hours or 15 days later. High temperature reduced total dry matter production and altered dry matter distribution in favor of vines at the expense of tubers. Partitioning of14C assimilates generally followed the pattern of dry matter distribution. Potato clones exhibited variation in14C assimilate export from labeled leaves and in partitioning to vines and tubers. Assimilate partitioning to tubers was not consistently higher in clones considered heat tolerant.