© 2000 Heron Publishing—Victoria, Canada
Acclimation of leaf characteristics of Fagus species to previous-year and current-year solar irradiances
Akira Uemura (1), Atsushi Ishida (1), Takashi Nakano (1, 3), Ichiro Terashima (2), Hiromi Tanabe (1, 3) and Yoosuke Matsumoto (1)
1. Forest Environment Division, Forestry and Forest Products Research Institute, P.O. Box 16, Tsukuba Norin Danchi, Ibaraki 305-8687,
Japan / 2. Department of Biology, Graduate School of Science, Osaka University, 1-16 Machikaneyama, Toyonaka, Osaka 560-0043, Japan / 3. Yamanashi Institute of Environmental Sciences, Fuji-Yoshida, Yamanashi 403-0005, Japan / Received August 12, 1999
Summary
To examine the effects of different solar irradiances on leaf characteristics at the leaf primordium and expansion stages,
we shaded parts of branches in the upper canopies of two adult beech trees, Fagus crenata Blume and Fagus japonica Maxim., for 4 years. The treatments during the leaf primordium and leaf expansion stages, respectively, were: (1) high light
and high light (H, control), (2) high light and low light (HL), (3) low light and low light (LL), and (4) low light and high
light (LH). Both number of cell layers in palisade tissue and individual leaf area were affected by the previous-year irradiance,
whereas cell length of palisade tissue was larger in LH leaves than in LL leaves, suggesting determination by current-year
irradiance. Lamina chlorophyll/nitrogen ratio was higher in HL and LL leaves than in LH leaves, suggesting determination by
current-year irradiance. Diurnal minimum values of leaf water potential measured under sunlit conditions were lower in H and
LH leaves than in HL and LL leaves. Effective osmotic adjustment was found in H and LH leaves, suggesting that leaf water
relations were affected by current-year irradiance. Net photosynthetic rate and stomatal conductance measured under sunlight
conditions were higher in H and LH leaves than in HL and LL leaves. Thus, effects of current-year irradiance had a greater
effect on leaf-area-based daily carbon gain than previous-year irradiance.
Keywords:
canopy shading experiment, chlorophyll, Fagus species, light acclimation, nitrogen, photosynthesis, water relations.
