Basal reiteration improves the hydraulic functional status of mature Cinnamomum camphora trees |
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Authors: | Takashi Otoda Hiroaki Ishii |
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Institution: | (1) Department of Plant Resources Science, Faculty of Agriculture, Kobe University, Kobe 657-8501, Japan;(2) Present address: Laboratory of Forest Ecology, Graduate School of Environmental Science, Okayama University, Okayama 700-8530, Japan;(3) Department of Plant Science, Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan |
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Abstract: | We compared soil-to-leaf hydraulic conductance (G
T), hydraulic conductivity and water-relations characteristics of leaves between reiterated axes (produced by sprouting of
suppressed buds) and sequential axes (produced by elongation of terminal buds) on the same branch to investigate how basal
reiteration affected the hydraulic architecture of mature Cinnamomum camphora (L.) Sieb. trees. Given similar light conditions, G
T was higher for leaves on reiterated shoots than for those on sequential shoots. However, where leaves on sequential shoots
received more light, G
T was similar to that of leaves on reiterated shoots, suggesting that some compensatory mechanism worked to increase hydraulic
conductance to the more distal sequential shoots, which have higher potential for carbon gain. Both xylem- and leaf-specific
conductivities were higher for reiterated than sequential shoots. Pressure–volume measurements indicated that leaves on reiterated
shoots were more vulnerable to water stress, suggesting that they developed under favorable water status. Because basal reiteration
occurs on lower-order branch axes, reiterated shoots have better connectivity to higher conducting xylem and this may contribute
to favorable water status. As trees grow larger, hydraulic pathlength and hydraulic resistance both increase as numbers of
branch junctions and nodes increase. Our results suggest that basal reiteration improves the hydraulic functional status of
mature C. camphora trees by shortening the hydraulic pathway and increasing hydraulic conductance to transpiring leaves. |
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Keywords: | Hydraulic conductance Water-relations characteristics Hydraulic conductivity Transpiration |
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