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Photoinhibition and recovery of cucumber seedling cotyledons under low temperatures

Zeng Jiqing, Liu Hongxian, Wang Yirou, Chen Yizhu

South China Institute of Botany, The Chinese Academy of Sciences. Guangzhou 510650, Guangdong

Abstract

Photoinhibition and recovery were studied in cucumber (Cucumis sativus L.) seedling cotyledons exposed to PFD^s of 50 and 100 #mu#mol m~(-2)s~(-1) at 4, 7, 10 and 15℃ by measurements of chlorophyll fluorescence with a PAM-Fluorometer. The Fv/Fm ratio of cucumber cotyledons decreased with the decline of temperature and the increace of PFD, and the exacerbation of photoinhibition at 4℃ was greater than that at 10 ℃ when PFD was increased equally. There was a slight recovery in the dark but light at the start of recovery was most important.Inhibitors were used in a preliminary study on the mechanism of chill-temperature photoinhibition. DTT partly inhibited the quenching of chlorophyll fluorescence Fm and Fo. Furthermore, the inhibitory effect at 15℃ was greater than that at 4℃. CAP exacerbated photoinhibition strongly and almost completely inhibited the recovery. Furthermore, CAP exacerbated photoinhibition strongly at 10℃, but only slightly at 4℃. The resistance to chill-temperature photoinhibition of cucumber cotyledons was enhanced by cold-hardening, but CAP exacerbated the photoinhibition of cold-hardened cucumber cotyledons more than that of the unhardened.

Key words: Cucumber low;Temperature;Photoinhibition;Chlorophyll fluorescence

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Citing This Article：

Zeng Jiqing, Liu Hongxian, Wang Yirou, Chen Yizhu. Photoinhibition and recovery of cucumber seedling cotyledons under low temperatures. Acta Physiol Sin 1997; 49 (1): (in Chinese with English abstract).