中文摘要：

叶绿体685nm延迟荧光成分被认为源于PSⅡ作用中心的电荷复合。利用多种光谱学测量手段研究了叶绿体延迟荧光光谱中730nm峰的产生机制。不同浓度下叶绿体延迟荧光光谱实验结果表明：初始随浓度的增加，延迟荧光光谱中685和730nm成分强度均增强；当浓度增加到7．8μg·mL^-1时，685nm成分强度达最大，730nm成分强度继续上升；当浓度增加到31．2μg·mL^-1时，延迟荧光光谱中730nm成分强度达最大，而685nm成分已明显下降。吸收光谱实验结果表明：A685／A730在叶绿体浓度增加的过程中几乎不变。叶绿体730nm荧光成分的激发光谱实验结果表明：685nm光对730nm荧光有较高的激发效率。上述实验结果表明叶绿体延迟荧光光谱中730nm峰是由PSⅡ所发685nm成分激发PSⅠ所产生的荧光。同一浓度下叶绿体延迟荧光光谱波形随延迟时间（1～9s）的不变性进一步证明了这一结论。

英文摘要：

Charge recombination in reaction center of photosystem Ⅱ （PSⅡ ） is regarded as the origination of delayed fluorescence （DF）. The mechanism for 730 nm component appearing in the DF spectrum of chloroplast was studied with different spectral analysis methods. Experimental results of the delayed fluorescence spectrum at different chloroplast concentration showed that the apexes at 685 and 730 nm ascend when the concentration is relative low; the peak value at 685 nm reaches a maximum when the concentration is 7.8 μg·mL^-1, however, the apex at 730 nm is still increasing. The peak value at 730 nm finally reaches a maximum at chloroplast concentration of 31.2 μg· mL^-1, while the apex at 685 nm has apparently decreased. The results of absorption spectrum showed that the ratios of A685 to A730 are almost a coustant during the process of increasing chloroplast concentration. Furthermore, the excitation spec trum for 730 nm fluorescence shows that the 685 nm light has a high excitation effidency. Above experimental results indicated that the 730 nm component of DF spectrum is the fluorescence of chlorophyll a in PSⅠ reaction center excited by 685 nm DF. Meanwhile, this conclusion was further verified by the invariability of DF spectrum at different delay time （1-9 s）.