The functional activities of the photosynthetic apparatus of two tomato cultivars of different thermotolerance were investigated after a short period of high temperature treatment. Seedlings of two tomato genotypes, Lycopersicon esculentum var. Campbell-28 and the wild thermotolerant Nagcarlang, were grown under a photoperiod of 16h at 25 degrees C and dark period of 8h at 20 degrees C. At the fourth true leaf stage, a group of plants was exposed to heat stress of 45 degrees C for 2 h. The heat shock treatment caused important reductions of the net photosynthetic rate (Pn) of Campbell-28 plants due to non-stomatal components. These non-stomatal effects were not evident in Nagcarlang-treated plants. This reduction in the CO2 assimilation rate observed in Campbell-28 was generated by affections in the Calvin cycle and also in the PSII functioning. No changes in these parameters were observed in the thermotolerant genotype after the stress. Injury to the plasma membrane because of the heat stress was evident only in the Campbell-28 genotype. Heat led to a sun-type adaptation response of the photosynthesis pigment apparatus for the Nagcarlang genotype, but not for Campbell-28, and thus an increase in chlorophyll a/b ratio and a decrease in chlorophyll/carotenoid ratio were shown in Nagcarlang stressed plants.

中文翻译：

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高温对两种不同热敏感性番茄品种光合活性的影响

研究了不同耐热性的两个番茄品种在短期高温处理后光合器官的功能活性。两种番茄基因型的幼苗，Lycopersicon esculentum var。Campbell-28 和野生耐热 Nagcarlang，在 25 摄氏度的 16 小时光照和 20 摄氏度的 8 小时黑暗期下生长。 在第四真叶阶段，一组植物暴露于 45 摄氏度的热应激2小时。由于非气孔成分，热激处理导致 Campbell-28 植物的净光合速率 (Pn) 显着降低。这些非气孔效应在 Nagcarlang 处理的植物中并不明显。在 Campbell-28 中观察到的 CO2 同化率的降低是由卡尔文循环和 PSII 功能中的影响产生的。在应激后，在耐热基因型中没有观察到这些参数的变化。由于热应激对质膜的损伤仅在 Campbell-28 基因型中明显。热量导致 Nagcarlang 基因型的光合作用色素装置的太阳型适应反应，但对于 Campbell-28 则不然，因此在 Nagcarlang 胁迫的植物中显示出叶绿素 a/b 比率的增加和叶绿素/类胡萝卜素比率的降低.