Differential Whole‐Plant Responses Among Potato Varieties ( Solanum tuberosum L) to an Episode of High Temperature

Studies have shown that the sensitivity of potato to high temperatures differs among growth stages, however, little is known about whether this is consistent among genotypes. This may be significant in selecting varieties for regions or systems which are likely to experience high temperatures at different stages of development. Therefore, the current study was aimed at testing the null hypothesis: ‘an episode of high temperature occurring at different stages causes similar changes in potato varieties both during and after the episode’. To test this, a series of three glasshouse experiments was conducted at Murdoch University, Perth, Western Australia. The control temperature was set at 20°C. A set of plants was exposed to an episode of high temperature (30°C ± 1°C) at different developmental stages in different experiments. Seven commercial potato varieties were screened for tolerance in Experiment 1, four of which (Atlantic, Maranca, Nadine & Laura) were selected for further study based on apparent differences in thermo‐tolerance. In Experiment 2, varieties were differently affected by high temperature in terms of total plant and tuber dry matter at 81 days after planting which was caused by the extent of recovery of varieties after the high temperature episode. The apparent tolerance of Atlantic differed between Experiment 1 (susceptible) and Experiment 2 (tolerant), which suggested that Atlantic's susceptibility was different between developmental stages. This was confirmed in Experiment 3. Mechanistically, the extent of recovery after a high temperature episode, the ability to sustain green leaves, and the capacity to sustain the rate of partitioning to tubers correlated to the thermo‐tolerance of varieties. Overall, these results indicate that the changes in thermo‐tolerance with growth‐stage are not necessarily consistent between varieties. This has implications for the suitability of varieties for specific heat stress scenarios and for methods of screening for thermo‐tolerance.