Effect of Cuticular Abrasion on Thermocouple PsychrometricIn SituMeasurement of Leaf Water Potential
| Autor: | Alfred Cass, Michael J. Savage, Herman H. Wiebe |
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| Rok vydání: | 1984 |
| Předmět: | |
| Zdroj: | Journal of Experimental Botany. 35:36-42 |
| ISSN: | 1460-2431 0022-0957 |
| DOI: | 10.1093/jxb/35.1.36 |
| Popis: | Cuticular resistance to water vapour diffusion between the substomatal cavity and the sensing psychrometer junction is a problem unique to leaf hygrometry. This resistance is not encountered in soil or solution hygrometry. The cuticular resistance may introduce error in the measurement of leaf water potential. Using in situ leaf hygrometers, we studied the effect of abrading the cuticle of Citrus jambhiri Lushington leaves, to reduce the diffusive resistance. Field measurements of psychrometer water potential were compared with Scholander pressure chamber values for adjacent leaves. Different treatments were compared by sealing pairs of psychrometers on either side of the midrib. The time for water vapour equilibration between the leaf and the psychrometer chamber was greater than 5 h for no abrasion. For abraded leaves, the true water potential value was obtained within an hour. After equilibration, psychrometer values compared favourably with pressure chamber values for adjacent leaves (r > 0-97). Measured water potential for unabraded leaves did not correlate well with corresponding pressure chamber measurements. Scanning electron micrographs indicated that the damage caused by abrading leaves for 60 s using carborundum powder (60 ftm diameter) was surface localized, with numerous scratchings of the leaf cuticle. The coarse abrasion treatment (aluminium oxide, 75 /?m diameter) resulted in fewer but larger cavities in the epidermis, which may explain the observed variability in the corresponding |
| Databáze: | OpenAIRE |
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