Acclimation in Seedlings of a Tropical Tree, Bischofia javanica, Following a Stepwise Reduction in Light |
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Authors: | KAMALUDDIN M; GRACE J |
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Institution: | Institute of Ecology and Resource Management, University of Edinburgh Edinburgh EH9 3JU, UK |
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Abstract: | Acclimation of fully developed leaves of Bischofia javanicaBlume to shadelight was examined. Seedlings were grown undersimulated daylight (1000 µmol m2 s1), thentransferred to a simulated shadelight (40 µmol m2s1). When a high-light leaf was transferred to low light, large negativenet photosynthetic rates (Pm) were recorded. This decrease wasrapid, but within 7 d the rate increased and became equal tothe low-light control leaf. These changes in photosynthesisdid not follow the pattern of changes in stomatal conductance(gs). Transfer to the low light resulted in a dramatic decreasein leaf weight per unit area (Lw), and most of the decreasesin Lw occurred within 3 d of transfer when the Pm of the transferredleaf was well below that of the low-light control leaf. There was a significant decrease in chlorophyll a in the transferredleaf without an appreciable change in chlorophyll b resultingin a large decrease in the chlorophyll a to chlorophyll b ratio.Leaf chlorophylls per unit area were higher in the transferredleaf than the low-light control leaf. Maximum photosyntheticrate in the transferred leaf was decreased by 40% compared tothat for the high-control leaf, but was almost at the same extenthigher than the low-light control leaf The results are discussedin the context of carbon gain capacity of its seedlings underlight-limiting forest understorey habitats. Bischofia, chlorophylls, light, photosynthesis, shade acclimation, tree seedlings, tropical tree |
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