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林业科学 ›› 2017, Vol. 53 ›› Issue (7): 18-36.doi: 10.11707/j.1001-7488.20170703

• 论文与研究报告 • 上一篇    下一篇

不同土壤水分条件下油松幼苗光合作用的气孔和非气孔限制——试验和模拟结果

郭文霞1,2,3, 赵志江4, 郑娇1, 李俊清1   

  1. 1. 北京林业大学森林培育与保护省部共建教育部重点实验室 北京 100083;
    2. 中国林学会 北京 100091;
    3. 悉尼科技大学植物功能生物学和气候变化研究组 新南威尔士 2007;
    4. 福建中咨工程咨询有限公司 福州 350003
  • 收稿日期:2016-03-01 修回日期:2017-03-21 出版日期:2017-07-25 发布日期:2017-08-23
  • 基金资助:
    Beijing to Build Key Discipline "Ecology" Project (20140801);High Level University Construction Project of China Scholarship Council (2012).

Stomatal and Non-Stomatal Limitation to Photosynthesis in Pinus tabulaeformis Seedling under Different Soil Water Conditions:Experimental and Simulation Results

Guo Wenxia1,2,3, Zhao Zhijiang4, Zheng Jiao1, Li Junqing1   

  1. 1. Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University Beijing 100083;
    2. Chinese Society of Forestry Beijing 100091;
    3. Plant Functional Biology and Climate Change Cluster, the University of Technology Sydney NSW 2007;
    4. Fujian CIECC Engineering Consulting Co. Ltd Fuzhou 350003
  • Received:2016-03-01 Revised:2017-03-21 Online:2017-07-25 Published:2017-08-23
  • Supported by:
    Beijing to Build Key Discipline "Ecology" Project (20140801);High Level University Construction Project of China Scholarship Council (2012).

摘要: [目的]了解不同土壤水分条件下油松幼苗叶片的气体交换特性及光合作用的气孔和非气孔限制,Ball-Berry模型、Leuning模型和Medlyn模型模拟的光合速率与气孔导度之间的关系,以及土壤水分含量和CO2供需对气孔模型的影响。[方法]测定4种不同土壤水分条件8%(W0)、12%(W1)、16%(W2)、20%(W3)下油松幼苗叶片的气体交换数据,并将实测数据与气孔模型的模拟数据进行对比。[结果]在4种土壤水分条件下都有明显的光合午休现象,中午净光合速率(A)和气孔导度(gs)都会下降;在中、低土壤水分条件下(W0、W1和W2),中午净光合速率和气孔导度的下降还伴随着胞间CO2浓度(Ci)的下降;然而,在高土壤水分条件(W3),中午净光合速率和气孔导度的下降却伴随着胞间CO2浓度的升高;在W0、W1和W2土壤水分条件下,气孔导度降幅比净光合速率大;相反,在W3土壤水分条件下,气孔导度降幅要比净光合速率小。在4个土壤水分条件下,净光合速率和气孔导度之间都具有高度相关性;在W0、W1和W2土壤水分条件下,Cigs之间也具有负相关,Ci随着gs的下降而降低,但在W3水分条件下,Ags之间具正相关;而Cigs之间的变化不规律。[结论]在W0、W1和W2土壤水分条件下,光合午休是由气孔关闭主导,而不是由叶肉细胞光合能力的下降主导;与此相反,在W3土壤水分条件下,光合午休是由非气孔限制,即叶肉细胞的光合能力降低主导。3个气孔模型的模拟结果表明,无论是采用全天数据还是采用上午和下午的数据,在4个土壤水分条件下,Medlyn模型的模拟效果都是最好的,而Medlyn模型的模拟效果,在不同土壤水分条件下,以及上午和下午存在明显差异。这说明Medlyn模型可以通过引入能够反映土壤水分条件对气孔行为影响的函数来得到改善;对于具有光合午休现象的植物来说,运用气孔模型进行模拟时应该将上午和下午的数据分开,分别模拟。当气孔限制和非气孔限制同时存在时,应该分别模拟光合速率与气孔导度之间的关系,并且可以给模型引入一个函数来提高模型的模拟效果。

关键词: 油松, 叶片气体交换, 气孔导度, 气孔经验模型, 气孔优化模型

Abstract: Midday depression in photosynthesis is common in plants, but the relative importance of stomatal and non-stomatal limitation to photosynthesis is variable among species. Pinus tabulaeformis is a conifer and distributed widely over China, which suggests its adaptability to a wide range of climate and soil water conditions. The aims of this study were to (a) understand the leaf gas exchange characteristics and stomatal and non-stomatal limitation of photosynthesis in P. tabulaeformis seedlings under different soil water conditions; (b) to compare the relationships between photosynthesis and stomatal conductance through simulation with three stomatal models; and (c) to determine the impact of the soil water content and the CO2 supply and demand on the simulation results. We measured diurnal variations in leaf-scale gas exchange of P. tabulaeformis seedlings grown under four soil water conditions:8% (W0), 12% (W1), 16% (W2) and 20% (W3) soil water content. There was a clear midday depression of net CO2 assimilation rate (A) and stomatal conductance (gs) in the all four soil water conditions. In the low and moderate soil water conditions (W0, W1 and W2), the midday depression in A and gs was accompanied with the decrease in intercellular CO2 concentration (Ci). However, in the high soil water condition (W3), the decreases in A and gs at midday were coupled with an increase in Ci. In addition, reduction of gs was bigger than the inhibition of A in the W0, W1 and W2. By contrast, in the W3 treatment, change in gs was in a smaller magnitude than the inhibition of A. Moreover, a high correlation between A and gs was observed across all treatments, and decrease in Ci paralleled to reductions in gs in W0, W1 and W2 treatments. However, in the W3 treatment, A and gs correlated positively with each other, and Ci remained unchanged at high gs and either increased or decreased at low gs. These results suggested that midday depression of A in W0, W1 and W2 soil water conditions was caused by closure of stomata rather than a decreased photosynthetic capacity of mesophyll cells. In contrast, midday depression in A in wet soil was controlled by non-stomatal decreases in the photosynthetic capacity of mesophyll cells. The comparison of stomatal models showed that the Medlyn model performed best in all of the four soil water conditions whether or not morning and afternoon were analysed separately. However the relationships between photosynthesis and stomatal conductance simulated by the Medlyn model differed significantly in different soil water treatments, and with morning and afternoon data separated, indicating that the Medlyn model can be improved by incorporating a function which can reflect the influence of soil moisture on the stomatal behaviour in different soil water conditions. Furthermore, it is suggested that the model simulations should be run separately in morning and afternoon for the plants that have remarkable midday depression in photosynthesis. Finally, we suggest that when both stomatal and non-stomatal limitations exist, the simulation of the relationships between photosynthesis and stomatal conductance should be operated separately, and a function, which assumes that stomatal conductance is regulated by rates of electron translation and by rates of Rubisco activity, or by the balance between the two processes, should be incorporated into the model to improve the simulation.

Key words: Pinus tabulaeformis, leaf gas exchange, stomatal conductance, empirical stomatal model, optimal stomatal model

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