The nature of heterogeneity in the stomatal behaviour of Phaseolus vulgaris L. primary leaves
| Autor: | Richard A'Brook, Jonathan D. B. Weyers, Tracy Lawson |
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| Rok vydání: | 1998 |
| Předmět: | |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 1460-2431 0022-0957 |
| DOI: | 10.1093/jxb/49.325.1387 |
| Popis: | The aim of this research was to investigate the nature of heterogeneity in stomatal conductance and, in particular, to determine whether the characteristic 'patchy' pattern of water infiltration is reflected in measurements on individual stomata. Silicone rubber replicas were made of primary leaves of glasshouse-grown Phaseolus vulgaris L. plants, and the leaves were then infiltrated with water at controlled subatmospheric gas pressures according to their estimated or measured stomatal conductance. Seven leaves examined in detail all showed patchy infiltration, and the mean size of infiltrated areas was negatively correlated with the prevailing stomatal conductance. In four of the leaves, a one millimetre wide transect across the leaf was selected for further detailed study. Measurements of mean peristomatal groove distance (PGD) and stomatal frequency were made along the transect and related to the state of infiltration. Analysis of variance indicated that, in all four cases, variation in PGD among patches was highly significant, but there was no significant difference between patches of different infiltration categories. Thus, local (patch-level) variation in stomatal aperture appeared to bear no relation to the infiltration status of the patches. The dominant source of stomatal variability was between individual pores in the same locality, which accounted for 82% or more of the total variability. Taking into account variation in stomatal frequency, correlations between predicted stomatal conductance and the extent of infiltration were significant in only one out of the seven leaves studied. Possible reasons for these results are discussed. It is suggested that the infiltration method misrepresents the underlying state of the stomata as being either open or closed, when there is little evidence for this from measurements of stomatal dimensions. For these unstressed plants under relatively stable conditions, it is concluded that the 'unit of variability' in stomatal heterogeneity may rest at the individual pore ('micro') scale, rather than at the areolar patch ('macro') scale, or above. |
| Databáze: | OpenAIRE |
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