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| DOI：10.13522/j.cnki.ggps.2019275 |
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| Regulatory Effect of Humic Acid on Chlorophyll Fluorescence Characteristics of Oat under Drought Stress |
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LI Yinghao, LIU Jinghui*, ZHAO Baoping, TIAN Lu, WANG Qi, ZHU Shanshan, DAI Yunxian
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Oat Scientific and Technical Innovation Team, Inner Mongolia Agricultural University, Hohhot 010019, China
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| Abstract: |
| Due to global climate change and the intensification of human activities, the water cycle conditions on the earth have undergone drastic changes, resulting in serious water problems and water environmental crisis in many regions and river basins. Water scarcity has become a bottleneck limiting sustainable agricultural development. Water is the main factor for crop production in semi-arid areas. Improving crop resistance and efficient use of water resources has become an inevitable choice for promoting sustainable agricultural growth in China's arid regions. Oat is an herbaceous plant belonging to the genus Oataceae of the family Poaceae, which is highly resistant to stress. It is widely planted in barren, arid, cold and other areas, and is a crop for both food and feed. Oat has a developed root system, strong water absorption capacity, large root and shoot, and strong water regulation capacity, and has become a pioneer crop for land desertification control. Already studies have shown that drought stress can destroy many metabolic and physiological processes of plants. Drought stress will reduce plant biomass, reduce chlorophyll content, and change chlorophyll fluorescence parameters, while photosynthesis is one of the most important physiological processes that plants are inhibited under drought stress, but its complex and precise physiological and biochemical regulation process is not clear. The effect of water stress on plant photosynthesis can be studied by analyzing chlorophyll fluorescence kinetic parameters. Changes in chlorophyll fluorescence parameters of plant leaves can accurately measure the level of plant photosynthetic potential and the degree of damage. The application of chlorophyll fluorescence kinetics can deeply analyze the effects of environmental stress on plant photosynthetic apparatus, especially PSⅡ, and the adaptation mechanism of photosynthetic apparatus to environmental changes. Humic acid is a kind of organic substances formed by the microbial decomposition and transformation of animal and plant remains. Humic acid helps to improve drought resistance of crops and delay plant senescence. Studies have shown that humic acid treatment significantly increased the actual photochemical efficiency (φPSⅡ) and photosynthetic electron transfer rate (ETR) of flag leaves in the late stage of wheat filling. Rarely.【Objective】The purpose of this study was to determine the effects of humic acid (HA) on the chlorophyll fluorescence characteristics of oat leaves under drought stress.【Method】Pot experiments were used to study effects on chlorophyll content and fluorescence parameters of oat leaves spraying HA under three water conditions: normal water supply (75% field capacity), moderate drought stress (60% field capacity), and severe drought stress (45% field capacity).【Result】(1) Water stress caused Chla+Chlb, Chla/Chlb, Fm, Fv, Fv/Fm, Fv/Fo, and qP to decrease significantly, while Fo and NPQ significantly increased; (2) Compared with CK, HA spraying under drought stress, Chla+Chlb increased by 0.6%～40.82%, Chla/Chlb increased by 1.13% to 30.09%, Fm increased by 0.7% to 121.19%, Fv increased by 1.0% to 171.79%, and Fv/Fm increased by 0.2% to 83.89% , Fv/Fo increased by 1.9% to 211.56%, qP increased by 0.1% to 68.30%, NPQ increased by 6.02% to 73.36%, and Fo decreased by 0.70% to 14.06%, among which significant differences were reached under severe drought stress. 【Conclusion】Drought stress caused obvious damage to the photoreaction system of oat PSⅡ. Spraying humic acid could alleviate its effect, and the effect was the most obvious under severe drought stress. |
| Key words: humic acid; oat; drought stress; chlorophyll; chlorophyll fluorescence parameters |
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