缺钾对茶树幼苗叶片叶绿素荧光特性的影响

为了探明缺钾对茶树叶片的光合电子传递、光能转化和利用等的影响机制，本研究以10月龄扦插瑞香茶Camellia sinensis (L.) O. Kuntze cv. Ruixiang] 苗为试验材料，通过沙培试验，用含5个不同钾浓度（K 0、100、200、600、2000 mol/L）的营养液浇灌，每周3次，处理24周后，进行茶树叶片叶绿素荧光参数的测定。结果表明，缺钾处理茶树叶片OJIP曲线O点上升，P点下降，同时出现150 s处的L点和300 s处的K点两个新点；缺钾条件下，TRo/ABS (or Fv/Fm) (最大光化学效率)、ETo/ABS（电子传递的量子产额）、REo/ABS（还原量子效率）、PIabs（吸收光能的性能指数）和PICS（单位面积为基础的性能指数）下降，而VJ、VI和耗散能增加。总之，缺钾损伤了从PSⅡ供体侧到PSI的整个电子传递链，降低了光合电子传递能力；缺钾叶片还通过增加热耗散以保护叶片在强光下免遭光氧化伤害。

Effects of potassium deficiency on chlorophyll fluorescence in leaves of tea seedlings

The objective was to determine the mechanism of the alteration of photosynthetic electron transport,light energy transformation and utilization of tea tree leaves under K deficiency. Vegetative propagated 10-month-old tea Camellia sinensis(L.) O. Kuntze cv. Ruixiang] seedlings grown in pots were fertilized three times weekly for 24 weeks with different nutrient solution contents,0,100,200,600 and 2000 μmol/L potassium.The results show that OJIP transients from the K-deficiency leaves display the decreased P-step and the increased O-step,and as well as two new steps at about 150 μs(L-step) and 300 μs(K-step) in the different spectra compared with the control.The RC/CSo,TRo/ABS(or Fv/Fm),ETo/ABS,REo/ABS,PⅠabs and PⅠcs are decreased in the K-deficiency leaves,while VJ,VI and dissipated energy are increased.In conclusion,The K deficiency decreases photosynthetic electron transport capacity by impairing the whole electron transport chain from PSⅡ donor side up to the PSⅠ.Enhanced energy dissipation protects the leaves of K-deficiency plants from photo-oxidative damage in high light.