以茶树[Camellia sinensis (Linn.) O. Ktze.]品种‘黄金芽’(‘Huangjinya’)和‘迎’(‘Yingshuang’)为实验材料,研究了4 ℃低温胁迫1、2、4 和6 d 对茶树叶片叶绿素荧光特性的影响。结果表明: 4 ℃低温胁迫条件下2 个茶树品种叶片的PSⅡ最大光化学效率(Fv / Fm)、PS域潜在活性(Fv / F0 )和表观光合电子传递速率(ETR)均显著低于各自的对照(25 ℃),且总体上随胁迫时间延长逐渐下降;‘黄金芽’叶片的光化学淬灭系数(qP)随低温胁迫时间延长持续下降且低于其对照,而‘迎霜’叶片的qP 较其对照的变幅较小,且2 个品种的qP 总体上与各自的对照无显著差异;随低温胁迫时间延长,2 个品种叶片的非光化学淬灭系数(NPQ)均先升高后降低,并在胁迫2 d 时达到最高,且总体上高于各自的对照;而2 个品种叶片的光合功能相对限制值(LPFD )均随低温胁迫时间延长而增大,且大多高于各自的对照。与各自的对照相比,低温胁迫条件下‘迎霜’叶片的各项叶绿素荧光参数的变幅总体上低于‘黄金芽”。研究结果显示:低温胁迫可直接损伤茶树叶片的PSⅡ反应中心,致使过剩的激发能大量积累于PSⅡ反应中心,最终导致茶树光合作用能力减弱。根据叶绿素荧光参数的比较结果,可以初步判定品种‘迎霜’的耐寒性优于品种‘黄金芽’。

Taking cultivars of ‘Huangjinya’and ‘Yingshuang’of Camellia sinensis (Linn.) O. Ktze. as experimental materials, effects of 4 ℃low temperature stress for 1, 2, 4 and 6 d on chlorophyll fluorescence characteristics in leaf of C. sinensis were researched. The results show that under 4 ℃low temperature stress condition, PSⅡmaximal photochemical efficiency (Fv / Fm), PSⅡpotential activity (Fv / F0) and apparent photosynthetic electron transport rate (ETR) in leaf of two cultivars of C. sinensisall are significantly lower than those of their respective control (25 ℃) and generally decrease gradually with prolonging of stress time. Photochemical quenching coefficient ( qP ) in leaf of ‘ Huangjinya’ decreases gradually with prolonging of low temperature stress time and is lower than that of its control, while that of ‘Yingshuang’has small change range to its control, and overall, there is no significant difference between qP of two cultivars and their respective control. With prolonging of low temperature stress time, non-photochemical quenching coefficient (NPQ) in leaf of two cultivars both increase firstly and then decrease and reach the highest when stress for 2 d, and generally are higher than that of their respective control. While, relative limit of photosynthesis (LPFD ) in leaf of two cultivars both increase with prolonging of low temperature stress time and mostly are higher than that of their respective control. Compared with their respective control, change ranges of chlorophyll fluorescence parameters in leaf of ‘Yingshuang’ are generally lower than those of ‘Huangjinya’ under low temperature stress condition. It is suggested that low temperature stress can directly damage PSⅡreaction center in leaf of C. sinensis, cause excess excitation energy to accumulate largely in PSⅡreaction center, eventually lead to weaken of photosynthetic capacity of C. sinensis. According to comparison result of chlorophyll fluorescence parameters, it can be preliminary judgment that cold resistance of cultivar ‘Yingshuang’is better than that of cultivar ‘Huangjinya’.