Xylem embolism and stomatal regulation in two rubber clones (<Emphasis Type="Italic">Hevea brasiliensis</Emphasis> Muell. Arg.) |
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Authors: | Krissada?Sangsing Poonpipope?Kasemsap Sornprach?Thanisawanyangkura Kumut?Sangkhasila Eric?Gohet Philippe?Thaler Email author" target="_blank">Hervé?CochardEmail author |
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Institution: | (1) Department of Agriculture, Rubber Research Institute, 10900 Bangkok , Thailand;(2) Department of Agronomy, Faculty of Agriculture, Kasetsart University, 10900 Bangkok , Thailand;(3) Department of Botany, Faculty of Science, Kasetsart University, 10900 Bangkok , Thailand;(4) Department of Soil Science, Faculty of Agriculture, Kasetsart University, 10900 Bangkok, Thailand;(5) Cirad-cp Rubber Program, Doras Center, Kasetsart University, 10900 Bangkok , Thailand;(6) UMR-PIAF, INRA, Site de Crouelle, 63039 Clermont-Ferrand, France |
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Abstract: | Vulnerability to water-stress-induced embolism of stems, petioles, and leaf midribs was evaluated for two rubber clones (RRIM600 and RRIT251). The xylem conduits were relatively vulnerable to cavitation with 50% of embolism measured for xylem pressures between –1 and –2 MPa. This feature can be related to the tropical-humid origin of the species. A distinct basipetal gradient of vulnerability was found, leaf midribs being the least vulnerable. Substantial variation in vulnerability to cavitation was found between the two clones only at the petiole level. A correlation was found between the stomatal behavior and the development of cavitation. Stomata were nearly closed when the xylem pressure reached the point of xylem dysfunction. Stomata may thus contribute to controlling the risk of cavitation. However, for one clone a poor correlation was found between stomatal regulation and petiole vulnerability. This was consistent with a high degree of embolism measured in the petioles after a soil drought event. Therefore, xylem cavitation might represent a promising criterion to evaluate the performance of rubber clones under drought conditions. |
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Keywords: | Water relations Hydraulic properties Cavitation Stomatal conductance Rubber tree |
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