期刊
JOURNAL OF EXPERIMENTAL BOTANY
卷 69, 期 22, 页码 5611-5623出版社
OXFORD UNIV PRESS
DOI: 10.1093/jxb/ery321
关键词
Bordered pit; branch; embolism; hydraulic segmentation; leaf; microCT; pit membrane; xylem
资金
- Chinese Scholarship Council (CSC)
- IdEx Bordeaux International Post-doctoral program fellowship [UB101 CR1024-R s/CR1024-6M]
- Humboldt Research Fellowship
- International Synchrotron Access Program
According to the hydraulic vulnerability segmentation hypothesis, leaves are more vulnerable to decline of hydraulic conductivity than branches, but whether stem xylem is more embolism resistant than leaves remains unclear. Drought induced embolism resistance of leaf xylem was investigated based on X-ray microcomputed tomography (microCT) for Betula pendula, Laurus nobilis, and Liriodendron tulipifera, excluding outside-xylem, and compared with hydraulic vulnerability curves for branch xylem. Moreover, bordered pit characters related to embolism resistance were investigated for both organs. Theoretical P-50 values (i.e. the xylem pressure corresponding to 50% loss of hydraulic conductance) of leaves were generally within the same range as hydraulic P-50 values of branches. P-50 values of leaves were similar to branches for L. tulipifera (-2.01 versus -2.10 MPa, respectively), more negative for B. pendula (-2.87 versus -1.80 MPa), and less negative for L. nobilis (-6.4 versus -9.2 MPa). Despite more narrow conduits in leaves than branches, mean interconduit pit membrane thickness was similar in both organs, but significantly higher in leaves of B. pendula than in branches. This case study indicates that xylem shows a largely similar embolism resistance across leaves and branches, although differences both within and across organs may occur, suggesting interspecific variation with regard to the hydraulic vulnerability segmentation hypothesis.
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