JOURNAL OF NANJING FORESTRY UNIVERSITY ›› 2021, Vol. 45 ›› Issue (2): 69-76.doi: 10.12302/j.issn.1000-2006.201909045

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Effects of flooding stress on leaf color and photosynthetic fluorescence characteristics of Liquidambar styraciflua cutting seedlings in summer

ZHONG Lei1,2(), ZHANG Huanchao1,*(), FAN Junjun3, ZHANG Dandan4, JIANG Hao1, ZHANG Wangxiang1   

  1. 1. Co-Innovation Center for the Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, Nanjing 210037, China
    2. Jiangsu Province Forest Seedling Management Station, Nanjing 210036, China
    3. College of Horticulture, Jinling Institute of Technology, Nanjing 211169, China
    4. Jinpu Landscape Co., Ltd., Nanjing 211100, China
  • Received:2019-09-23 Accepted:2020-04-08 Online:2021-03-30 Published:2021-04-09
  • Contact: ZHANG Huanchao E-mail:390923265@qq.com;hczhang@njfu.edu.cn

Abstract:

【Objective】The purpose of this experiment is to estimate the flooding resistance of Liquidambar styraciflua and to analyze the flooding resistance mechanism, combined with the synergy of leaf color, leaf pigments and photosynthetic fluorescence characteristics.【Method】The dynamic trends of growth, leaf color (color parameters and pigment ratio), photosynthetic characteristics [net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), intercellular CO2 concentration (Ci)]; and chlorophyll dynamic fluorescence characteristics [leaf reaction center number (NRC/CSm), efficiency by trapped exciton (Ψo), quantum ratio for electron transfer (φRo), quantum yield of electron acceptor at the end of acceptor side (φEo), dissipation (EDIo/CSm), and performance index (Itotal)] of one-year-old cuttings of L. styraciflua were analyzed under 60 days of flooding treatment outdoors in summer at high temperatures. 【Result】①The growth of L. styraciflua was not inhibited by flooding treatment after 60 days, and the survival rate of cuttings was still up to 90%. ② The leaf color parameter (h) decreased significantly with prolongation of flooding. After 40 days, the color of the leaves changed from green to red (h< 90°). ③ The relative content ratio of chlorophyll to anthocyanin and carotenoid [Chl/(Anth+Car)] showed a significant decreasing trend after 20 days. After 40 days, the ratio of pigments was less than 1. The change in pigments was synchronized with that of the leaf color parameters. ④ The trend of photosynthetic gas exchange parameters of treated cuttings was similar to that of the control. Both Pn and Ci showed downward-upward-downward trend, while Tr and Gs showed downward trend. In the early stage of flooding (0-20 days), there was no significant difference between the treatment and control groups, but in the late stage of flooding (20 days later), the values of each parameter were significantly lower than that of the control, and the difference between them increased. ⑤ The characteristics of the light response curve showed that the Pn of the treatment was significantly lower than that of the control, and with flooding prolongation, the difference in Pn between the treatment and control was larger than that of the control, which indicated that the light utilization rate of the treatment was lower. ⑥ With prolonged flooding (after 30 days of flooding), the number of leaf reaction centers (NRC/CSm) and the energy of electronic transmission from PSII to PSI (Ψo, φRo and φEo) were significantly decreased, and the EDIo/CSm was significantly increased, which resulted in a decrease in the performance index (Itotal). 【Conclusion】The L. styraciflua has strong short-term flooding tolerance. All indexes of treatments were better than those of the control in the first 20 days. This was because of the reduction in excitation energy generation and excess excitation energy damage by increasing the heat dissipation of leaves, thereby adjusting the weight of the photosynthetic pigment content. There was synergism among net photosynthetic rate, leaf pigment ratio and fluorescence parameters, and the time of inflection of each parameter changed rhythmically, that is, 20, 30 and 40 days, respectively. The photosynthetic parameter response was the most sensitive.

Key words: flooding stress, Liquidambar styraciflua, color space, characterization of photosynthesis, chlorophyll fluorescence, synergy, summer

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