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Chinese Agricultural Science Bulletin ›› 2022, Vol. 38 ›› Issue (29): 67-73.doi: 10.11924/j.issn.1000-6850.casb2021-1035

Special Issue: 生物技术 园艺

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Short-term Response of Photosynthesis and Chlorophyll Fluorescence Characteristics of Fir Seedlings to Nitrogen Deposition

ZHAO Jiaojiao(), AI Jianguo()   

  1. College of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou 311300
  • Received:2021-11-01 Revised:2022-01-15 Online:2022-10-15 Published:2022-10-14
  • Contact: AI Jianguo E-mail:1064592051@qq.com;aijianguo@yahoo.com.cn

Abstract:

To explore the change law of the photosynthesis and chlorophyll fluorescence characteristics of fir seedlings under simulated nitrogen deposition condition, the short-term response of fir seedlings to nitrogen deposition in different seasons was discussed from the perspective of photosynthesis physiology. The fir seedlings were selected as experimental subjects, and the nitrogen deposition experiment was simulated with four treatment levels of the control (N0), low nitrogen (N30:30 kg/(hm2.a)), medium nitrogen (N60:60 kg/(hm2.a)), and high nitrogen(N90:90 kg/(hm2.a)). The results showed that after adding nitrogen, the net photosynthesis rate (Pn), initial fluorescence yield (F0), maximum fluorescence yield (Fm), maximum PSII light energy conversion efficiency (Fv/Fm) and PSII potential activity (Fv/F0) were significantly reduced, while water utilization rate (Wue) increased significantly (P<0.05). With the increase of nitrogen deposition level, stomatal conductance (Gs) and transpiration rate (Tr) showed a tendency of increase first and then decrease, and the water use efficiency showed a trend of first decrease then increase. With the medium and high nitrogen treatment, Fv/Fm and Fv/F0 values were significantly reduced (P<0.05). In winter, the net photosynthesis rate was significantly and positively correlated with stomatal conductance, transpiration rate and intercellular CO2 concentration (P<0.01); and in spring, the net photosynthesis rate was significantly and positively correlated with stomatal conductance and transpiration rate (P<0.01), and negatively correlated with intercellular CO2 concentration. After the accumulation of nitrogen deposition reached a certain threshold, the water loss was increased, which reduced the water utilization efficiency of the plant. In winter, the net photosynthesis rate was mainly affected by the stomatal limit, heat dissipation increased, and the PSII reaction center showed photo-suppression phenomenon; when it turned to spring, the excessive accumulation of nitrogen deposition destroyed the photosynthesis structure of seedlings, resulting in an increase in the concentration of carbon dioxide between cells and a decrease in the net photosynthesis rate. Then the non-stomatal limits became the main reason for the impact on the net photosynthesis rate. The medium nitrogen treatment could reduce the potential activity of PSII in chlorophyll, and the photosynthetic electron transfer capacity of the photoreaction center decreases, resulting in the decrease of photosynthesis efficiency.

Key words: nitrogen deposition, fir seedling, gas exchange parameters, chlorophyll fluorescence parameters

CLC Number: