Báo cáo lâm nghiệp: Responses of photosynthesis and stomatal conductance to atmospheric humidity in some mediterranean Abies specie

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Responses of photosynthesisand stomatal conductance to atmospheric humidity in some mediterranean Abies species...
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Báo cáo lâm nghiệp: "Responses of photosynthesis and stomatal conductance to atmospheric humidity in some mediterranean Abies specie"Responses of photosynthesisand stomatal conductance to atmospherichumidity in some mediterranean Abies speciesJ.M. Guehi J. Bouachrine’ 1 2 Zimmermann E. 1 Dreyer R.! Laboratoire de Bioclimatologie-Ecophysiologie Forestiere, Station de Sylviculture et Production,INRA, Centre de Nancy, F-54280 Seichamps, France, andLehrstuhl2 fOr Pfanzenökologie, Universität Bayreuth, Postfach 3008, D-8580 Bayreuth, F.R.G. sessed under controlled environmental condi-Introduction tions with an open gas-exchange measurement system on intact or excised shoots of differentLeaf gas-exchange has long been shown mediterranean coniferous species. Stomatalto be sensitive to changes in the water conductance (g! and intercellular C0 concen- 2vapor mole fraction difference between the tration (Ci) were calculated from the gas- exchange data using classical equations (seeleaf and the air (Aw ) (Sandford and Jar- Guehl and Aussenac, 1987). Prior to dw beingvis, 1986; Schulze, 1986). It has been pro- increased, the short-term response of gas-posed (Guehl and Aussenac, 1987; Grieu exchange to increasing ambient C0 concen- 2et al., 1988) that decreasing C0 assimila- 2 tration (C was assessed, and the corre- ) ation in response to increasing Aw is not sponding A(Ci) functions were determined, thus allowing the analysis of C0 assimilation in 2only due to stomatal closure, but could be, terms of mesophyll photosynthetic capacityat least partially, a consequence of altered (demand function, see Fig. 1) and diffusionalmesophyll photosynthetic capacity. How- limitation of C0 supply to the chloroplasts 2ever, that interpretation is not consensual (supply function). The A(CiJ functions were also used to determine the marginal water cost of(Terashima et al., 1988). We report herein C0 assimilation (DEJDA) (Guehl and Aussenac, 2results providing further evidence for the 1987) and to examine the gas-exchange regu-existence of a mesophyll effect in re- lation with respect to the optimization theory ofsponse to increasing Aw in some mediter- Cowan and Farquhar (1977).ranean Abies species. The study was alsoaimed at determining whether the differentspecies examined exhibit differences in Results and Discussiontheir water use efficiencies. Increasing Aw resulted in markedly low- ered A (Fig. 1 a) and g (Fig. 1 b) in seed- sMaterials and Methods lings of Abies nordmanniana. Stomatal closure was efficient enough for theResponses of C0 assimilation rate (A) and 2 E (dw) response to exhibit a maximum attranspiration rate (E) to varying dw were as- tion (Terashima et al., 1988), was shownabout Aw = 12 Pa-kPa- (Fig. 1c), thus 1 in the second phase of the experiment insupporting the postulate (Schulze, 1986) which Aw was returned near its initial lowthat ...