Two newly bred hybrid rice combinations, super high-yielding Liangyoupeijiu (Pei’ai 64S×9311) and Pei’ai 64S/E32 (Pei’ai 64S×E32) were used to investigate the photosynthetic characteristics under high temperature in comparison with hybrid rice Shangyou 63. High temperature caused a decreased photosynthetic efficiency and aggravated photoinhibition. The optimum temperature for photosynthetic electron transportation and photosynthetic CO2 fixation were about 28℃ and 35–40℃ respectively. Linear electron transportation is more sensitive to high temperature than the photochemical process. The mechanism of high temperature adaptation was possibly as follows: super high-yielding rice has quickly increasing carotenoid, which acted as a more favorable antioxidant system to reduce the active oxygen production and avoid damage to the photosynthesis system; super high-yielding rice has a higher efficiency of xanthophylls cycle to dissipate excess heat energy; super high-yielding rice has a more stable photosynthetic function, higher photosynthetic efficiency and more heat stable protein content.
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