| Effects of water stress on community photosynthesis of plants and its relationship of typical grassland in Northern China |
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| DOI：10.7606/j.issn.1000-7601.2020.01.31 |
| Key Words: grassland plant community water stress photosynthesis soil moisture Xilinhot |
| Author Name | Affiliation | | WANG Haimei | Ecological and Agricultural Meteorological Center in Inner Mongolia, Huhhot, Mongolia 010051, China | | JIA Chengzhen | Ecological and Agricultural Meteorological Center in Inner Mongolia, Huhhot, Mongolia 010051, China | | LI Huirong | Xilinhot National Climatological Observatory, Xilinhot, Mongolia 026000, China | | JIN Linxue | Ecological and Agricultural Meteorological Center in Inner Mongolia, Huhhot, Mongolia 010051, China | | HOU Qiong | Ecological and Agricultural Meteorological Center in Inner Mongolia, Huhhot, Mongolia 010051, China |
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| Abstract: |
| Considering the sensitivity of photosynthesis to soil moisture, the paper analyzed the limited degree of photosynthesis under different water stress conditions in typical steppe communities based on the soil moisture and photosynthesis observations from the national climate observatory of Xilinhot from 2016 to 2017. The analysis showed that, the population photosynthetic rate of each plot was at a low level during the early and late period of forage growth from herbage turning green to early June, and there was no significant inhibition of photosynthesis was observed in water\|controlled plots. Then, the population photosynthetic rate increased significantly after the forage entered a vigorous growth period in July, and reached the highest value in early August (≥10.89 μmol·m-2·s-1), the effect of water stress on the photosynthesis of the population was very significant. Soil moisture content of 10~20 cm soil layer had the best correlation with photosynthetic rate and respiration rate, and had the best correlation with surface soil moisture, which indicated that plant roots and soil microbes were most concentrated in this layer. There was a good linear regression relationship between soil moisture content above 30 cm soil and population photosynthetic rate, and F test showed that the linear fitting effect was very significant, which indicated that soil moisture content above 30 cm affected photosynthesis of typical grassland plant population. The MK mutation test showed that when volumetric water content of 0~10 cm soil layer of typical steppe was lower than 9% (the weight water content is 6.82%, and the relative water content is 27.60%), and the volumetric water content of 0~30 cm soil layer of typical steppe was lower than 12% (the weight water content was 9.57%. In typical grassland drought forecasting and early warning, the population photosynthetic rate was obviously inhibited, and it could be regarded as occurrence the critical value of soil moisture during moderate drought in typical grassland. |
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