Plants and the Environment. In situ observation of stomatal movements and gas exchange of Aegopodium podagraria L. in the understorey
Authors: Kaiser, H.; Kappen, L.
Source: Journal of Experimental Botany, Volume 51, Number 351, October 2000 , pp. 1741-1749(9)
Publisher: Oxford University Press
Abstract:Observations of stomata in situ while simultaneously measuring CO2 gas exchange and transpiration were made in field experiments with Aegopodium podagraria in a highly variable light climate in the understorey of trees. The low background photosynthetic photon flux density (PPFD) caused a slight opening of the stomata and no visible response to sporadic lightflecks. However, if lightflecks were frequent and brighter, slow opening movements were observed. Small apertures were sufficient to allow maximal photosynthetic rates. Therefore, the small apertures observed in low light usually only caused minor stomatal limitations of lightfleck photosynthesis. The response of stomata to step-wise changes in PPFD under different levels of leaf to air vapour pressure difference (ΔW) was observed under controlled conditions. High ΔW influenced the stomatal response only slightly by reducing stomatal aperture in low light and causing a slight reduction in the initial capacity to utilize high PPFD levels. Under continuous high PPFD, however, stomata opened to the same degree irrespective of ΔW. Under high ΔW, opening and closing responses to PPFD-changes were faster, which enabled a rapid removal of the small stomatal limitations of photosynthesis initially present in high ΔW after longer periods in low light. It is concluded that A. podagraria maintains a superoptimal aperture in low light which leads to a low instantaneous water use efficiency, but allows an efficient utilization of randomly occurring lightflecks.
Document Type: Regular Paper
Affiliations: Botanisches Institut der Christian-Albrechts-Universität zu Kiel, Olshausenstraße 40, D-24098 Kiel, Germany
Publication date: 2000-10-01
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