TAILIEUCHUNG - Báo cáo lâm nghiệp: "Stomatal conductance and xylem-sap abscisic acid (ABA) in adult oak trees"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế, đề tài:"Stomatal conductance and xylem-sap abscisic acid (ABA) in adult oak trees. | Ann Sci For 1996 53 207-220 Elsevier INRA 207 Original article Stomatai conductance and xylem-sap abscisic acid ABA in adult oak trees during a gradually imposed drought MB Triboulot1 2 ML Fauveau 1 2 N Bréda 1 p Label 2 E Dreyer 1 Équipe bioclimatologie et écophysiologie unite d ecophysiologie forestiere Centre de Nancy Inra 54280 Champenoux 2 Unite physiologie du développement laboratoire d amelioration des arbres forestiers Centre d Orleans Inra 45160 Olivet France Received 18 October 1994 accepted 19 June 1995 Summary Thirty- to 40-year-old oak trees Quercus petraea Matt Liebl and Q robur L growing in a forest stand near Champenoux Nancy France were submitted to an imposed drought in a lysimeter during two successive summers. Xylem sap was extracted from leafy twigs of two trees per species at regular intervals during the onset of drought and of two controls in parallel. Predawn leaf water potential soil water potential at different depths and midday stomatai conductance of sun-exposed leaves were recorded at the same pace. Concentrations of abscisic acid ABA and of the glucose ester of ABA ABA-GE were measured with an ELISA technique after purification of the sap samples using high performance liquid chromatography HPLC . Mean concentrations of ABA recorded in the absence of drought constraint were around 30 pmol m-3 independently from year and species and 45 pmol m-3 for ABA-GE. No significant drought-related increase in either of these concentrations could be recorded while predawn leaf water potential dropped below MPa and stomatai conductance down to 10 of the values of controls. A good correlation between stomatai conductance and predawn leaf water potential was detected and even a better one between stomatai conductance and soil water potential at 25 cm. It may be concluded from these results that even if a close correlation exists between stomatai aperture and soil moisture the existence of a root signalling process based solely on increased ABA .

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