Plants are very sensitive to environmental stresses, particularly to high temperature (HT) which is predicted to increase. This study was conducted to investigate the response to HT for identifying physiological traits associated with HT tolerance in tomato. Thirty-eight tomato accessions with three fruit sizes (cherry, medium and large) were grown in greenhouses where temperature set-point for ventilation was 25 °C and 40 °C for normal temperature (NT) and HT, respectively. HT increases plant height and stem diameter but little effect on leaf length and width. For reproductive traits, HT has positive effect on the number of flowers (NFL) but negative on the number of fruits (NFR), fruit set (FS), weight (FW) and yield (FY), and pollen germination (PG) and tube length. In the correlation analysis, except for accession T37 with extreme value causing spurious results, PG did not show significant correlation with FS, FW and FY, but with NFL and NFR in HT condition. NFR (HT), FS (HT) and FY (NT) are identified as physiological traits associated with HT tolerance based on correlation with FY (HT). However, their association to HT tolerance differ by fruit sizes. NFR (HT) was significantly correlated with FY (HT) in sub-population of cherry (r = 0.859**, n = 14), medium (r = 0.848**, n = 7) and large fruit types (r = 0.769**, n = 16) but not in total population (r = 0.302NS, n = 37). FS (HT) and, interestingly, FY (NT) were significantly correlated with fruit yield (HT) in total population and a cherry fruit sub-population but not in medium and large fruit sub-population. Results suggest that physiological traits associated with HT tolerance differ by fruit size and breeding programs should consider different selection criteria for different fruit types when develop cultivars with HT tolerance.

中文翻译：

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与耐高温相关的生理性状因番茄 (Solanum lycopersicum L.) 的果实类型和大小而异

植物对环境压力非常敏感，特别是对预计会增加的高温 (HT)。本研究旨在调查对 HT 的反应，以确定与番茄耐 HT 相关的生理性状。在温室中种植 38 个具有三种果实大小（樱桃、中号和大号）的番茄种质，其中通风温度设定点分别为 25 °C 和 40 °C，常温 (NT) 和 HT。HT增加了株高和茎直径，但对叶长和宽度影响不大。对于生殖性状，HT对花数（NFL）有积极影响，但对果实数（NFR）、坐果数（FS）、重量（FW）和产量（FY）以及花粉发芽率（PG）和管长。在相关分析中，除了加入T37极值导致虚假结果外，PG与FS，FW和FY没有显着相关性，但与HT条件下的NFL和NFR相关。基于与 FY (HT) 的相关性，NFR (HT)、FS (HT) 和 FY (NT) 被确定为与 HT 耐受性相关的生理特征。然而，它们与 HT 耐受性的关联因果实大小而异。NFR (HT) 与樱桃亚群 (r = 0.859**, n = 14)、中等 (r = 0.848**, n = 7) 和大型果实类型 (r = 0.769) 中的 FY (HT) 显着相关**，n = 16）但不在总人口中（r = 0.302NS，n = 37）。FS (HT) 和有趣的是 FY (NT) 与总人口和樱桃果实亚群的果实产量 (HT) 显着相关，但与中型和大型果实亚群的果实产量 (HT) 无关。