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低温胁迫恢复过程中不同回温速度对油茶光系统活性的影响

Effect of temperature return rate on photosystem activity of Camellia oleifera during recovery from low temperature stress

  • 摘要: 为探讨低温胁迫及不同回温速度对油茶光系统I( PS Ⅰ)和光系统II(PS Ⅱ)活性的影响,以2年生‘长林40’油茶嫁接苗为试验材料,低温(−5 ℃)胁迫24 h后,以30、5、2.5 ℃/h升温至室温(25 ℃),测定油茶叶片叶绿素荧光快速诱导动力学曲线和对P 700+氧化还原动力学曲线,并进行叶绿素荧光淬灭分析。结果表明:低温胁迫24 h后,油茶叶片PS Ⅱ和PS Ⅰ的活性均发生不同程度的光抑制。在恢复阶段,PS Ⅱ和 PS Ⅰ活性对回温速度均比较敏感,PS Ⅱ活性随着回温速度的增加而加快;与此同时, PS Ⅰ活性在快速回温速度(30 ℃/h)下恢复较慢,在慢速回温速度(2.5 ℃/h)下恢复较快。快速回温促进了油茶叶片线性电子传递速率的恢复。温度回升越快恢复过程中的PS Ⅱ向PS Ⅰ传递的电子数量越多。而过多电子数量降低了P 700氧化水平,进一步加剧了PS Ⅰ的光抑制。因此,在油茶低温胁迫恢复过程中,较快的回温速度下PS Ⅱ活性恢复的加快会引起流向 PS Ⅰ的光合电子的增加,进而加剧PS Ⅱ和 PS Ⅰ活性的不匹配,生产中应当在低温发生之后采取措施防止温度回升过快,从而有利于油茶光系统的保护和修复。

     

    Abstract: Low-temperature stress is a common adverse condition in oil tea cultivation during winter and spring, which greatly impacts plant photosynthesis. The investigation found a close correlation between low temperature injury and the temperature return rate after low temperature relief. The sharp rise in temperature after low-temperature is often accompanied by serious low temperature injury. In this study, the effects of low-temperature stress and different temperature return rates on the activity of photosystem I ( PS Ⅰ) and photosystem II (PS Ⅱ) of Camellia oleifera were investigated. 2-year-old potted seedlings of Camellia oleifera 'Changlin40' were used as the test material. After being stressed at low temperature (−5 ℃) for 24 hours, the temperature was heated to room temperature(25 ℃) at rates of 30, 5, 2.5 ℃/h. The rapid induction kinetic curves of chlorophyll fluorescence and the redox kinetic curves of P 700+ were determined, and the chlorophyll fluorescence was quenched. After 24 hours of low-temperature stress, photoinhibition of PS Ⅱ and PS Ⅰ activities of Camellia oleifera leaves occurred to different degrees. In the recovery stage, both PS Ⅱ and PS Ⅰ activities are sensitive to the return temperature rate, and PS Ⅱ activity accelerates with the increase in the return temperature rate. At the same time, PS Ⅰ activity recovers slowly at the fast return temperature rate(30 ℃/h) and faster at the slow return temperature rate(2.5 ℃/h). Rapid temperature rise promotes the recovery of linear electron transfer rate in Camellia oleifera leaves. The faster the temperature rises, the more electrons are transferred from PS Ⅱ to PS Ⅰ during the recovery process. The excessive number of electrons decreases the oxidation level of P 700, which further intensifies the photoinhibition of Pⅰ. In the recovery process of Camellia oleifera under low-temperature stress, the acceleration of PS Ⅱ activity recovery at a faster temperature return rate will lead to an increase in photosynthetic electrons flowing to PS Ⅰ, further aggravating the mismatch between PS Ⅱ and PS Ⅰ activities. Measures should be taken to prevent the temperature from rising too fast after the occurrence of low temperature in production, to facilitate the protection and repair of Camellia oleifera photosystem.

     

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