Differences in photosynthetic activity, chlorophyll and carotenoid levels, and in chlorophyll fluorescence parameters in green sun and shade leaves of Ginkgo and Fagus

The differences in pigment Levels and photosynthetic activity of green sun and shade leaves of ginkgo (Ginkgo biloba L.) and beech (Fagus sylvatica L.) are described. Sun leaves of both tree species possessed higher levels in chlorophylls (Chl) and carotenoids on a leaf area basis, higher values for the ratio Chl a/b and Lower values for the ratio Chl/carotenoids (a+b)/(x+c) in comparison to shade leaves. The higher photosynthetic rates P-N of sun leaves (ginkgo 5.4 +/- 0.9 and beech 8.5 +/- 2.1 mu molm(-2)s(-1)) were also reflected by higher values for the Chl fluorescence decrease ratios R-Fd 690 and R-Fd 735. In contrast, the shade leaves had tower P-N rates (ginkgo 2.4 +/- 0.3 and beech 1.8 +/- 1.2 mu mol m(-2) s(-1)). In both tree species the stomatal. conductance G, was significantly higher in sun (range: 70-191 mmolm(-2) s(-1)) as compared to shade leaves (range: 5-55 mmol m(-2) s(-1)). In fact, at saturating tight conditions there existed a close correlation between G(s) values and P-N rates. Differences between sun and shade leaves also existed in several other Chl fluorescence ratios (F-v/F-m, F-v/F-o, and the stress adaptation index Ap). The results clearly demonstrate that the fan-shaped gymnosperm ginkgo leaves show the same high and tow irradiance adaptation response as the angiosperm beech leaves. (c) 2006 Elsevier GmbH. All rights reserved.