Modification of chlorophyll fluorescence (PAM) plant stress and its research methods
December 31 15:20:15, 2020
BeijingAozuEcological Instrument Co., Ltd.
In 1960, Kautsky and his assistants first discovered changes in chlorophyll fluorescence production. They found that when the plants were transferred from the dark-adapted state to the light, the chlorophyll fluorescence yield rose rapidly within 1 s. At this stage, the PSII reaction center was considered to be closed, the photochemical efficiency was lowered, and the chlorophyll fluorescence yield was increased. In the next few minutes, the fluorescence yield gradually decreased, a phenomenon known as chlorophyll fluorescence quenching. There are two cases of chlorophyll fluorescence quenching: First, the increase of PSII electron transport rate, which is caused by photoactivation and stomatal opening of carbon metabolism enzymes, called photochemical quenching; second, the efficiency of energy conversion into heat dissipation increases. It is called non-photochemical quenching.
The application of chlorophyll fluorescence analysis technology enables people to understand the light energy absorption, conversion and utilization efficiency of plant photosynthetic systems from a more microscopic level. Chlorophyll fluorescence can obtain information that is not available in other methods. Fluorescence can provide valuable information on the ability of plants to withstand environmental stress and the extent to which various stresses have compromised the photosystem. In the physiological and ecological study of environmental stress, the commonly used parameters of fluorescence analysis are: the maximum quantum yield of photosystem II, the actual quantum yield of photosystem II, the photochemical quenching coefficient, the non-photochemical quenching coefficient, and the excitation energy of the photosystem II reaction center. Efficiency, relative electron transfer rate.
At present, the research on chlorophyll fluorescence in the world has become a hot spot, and has been widely used in the study of stress physiology such as glare, high temperature and drought.
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