Abstract
Genotypic variability in vulnerability of leaf xylem to water-stress-induced cavitation was determined in four sugarcane (Saccharum sp.) clones using detached leaf segments in a hydraulic conductivity apparatus. Vulnerability curves were constructed by plotting the percentage of maximum conductivity versus leaf water potential (ψI) and fitting curves using a Weibull function. The ψI at which each clone lost 10, 50, and 80% of maximum conductivity was determined. Maximum conductivity per unit of leaf width was positively associated with metaxylem vessel diameter. The commercial clone H65-7052 exhibited the highest and the nondomesticated S. spontaneum exhibited the lowest conductivity. All four clones lost substantial conductivity at values of ψI less negative than −1.4 MPa, but H65-7052 was able to maintain 50% conductivity to lower ψI than the other clones. S. spontaneum sustained the most negative ψI (−1.99 MPa) before reaching the 80% conductivity loss point. Clone H69-8235 was consistently the most vulnerable to initial loss of conductivity. These vulnerability functions were used in conjunction with field measurements of ψI to estimate diurnal losses in leaf hydraulic conductivity under irrigated and droughted conditions. H69-8235 lost up to 50% of its conductivity during the day, even when well irrigated, and more than 80% when subjected to drought. The other clones exhibited lower conductivity losses. These losses are apparently reversed overnight by root pressure. Despite their close genetic relationships, these clones exhibited large differences in conductivity, in the vulnerability of their xylem to cavitation, and in gas exchange behavior. The potential for altering water relations by selecting for particular hydraulic characteristics is discussed.
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Selected References
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- Sperry J. S. Relationship of Xylem Embolism to Xylem Pressure Potential, Stomatal Closure, and Shoot Morphology in the Palm Rhapis excelsa. Plant Physiol. 1986 Jan;80(1):110–116. doi: 10.1104/pp.80.1.110. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tyree M. T., Fiscus E. L., Wullschleger S. D., Dixon M. A. Detection of Xylem Cavitation in Corn under Field Conditions. Plant Physiol. 1986 Oct;82(2):597–599. doi: 10.1104/pp.82.2.597. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Tyree M. T., Sperry J. S. Do woody plants operate near the point of catastrophic xylem dysfunction caused by dynamic water stress? : answers from a model. Plant Physiol. 1988 Nov;88(3):574–580. doi: 10.1104/pp.88.3.574. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Van Alfen N. K., McMillan B. D., Turner V., Hess W. M. Role of pit membranes in macromolecule-induced wilt of plants. Plant Physiol. 1983 Dec;73(4):1020–1023. doi: 10.1104/pp.73.4.1020. [DOI] [PMC free article] [PubMed] [Google Scholar]