2018 ASHS Annual Conference

In many cases, testing tomato cultivars for temperature tolerance involves subjecting the entire plant (including roots) to high or low temperatures and fails to distinguish the impact of root system stress in overall plant photosynthetic responses. We previously determined root respiration rates of eight tomato cultivars varying in heat tolerance that also vary in root respiration responses to root zone temperatures ranging from 44.1 to 59.1 ^oC (+/- 0.4 ^oC). In this study, root temperatures of heat tolerant and heat intolerant tomato varieties were maintained at 25 ^oC and 55 ^oC (previously determined as a non-stressful and stressful temperature, respectively) while aboveground stem and leaf tissues were maintained at 26^oC (previously identified as optimal for photosynthesis in tomato) to determine whether photosynthetic activity of heat tolerant and intolerant tomato varieties was impacted by high root temperatures differently. Specifically, we sought to determine the degree to which aboveground photosynthetic activity is associated with root sensitivity to high temperature.