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[C-2.3 Studies on Dynamics of Heavy Metals in Woody Plants on Acid Soils]

[Contact Person]

Mitsutoshi Kitao
Shigeta Mori
Yutaka Maruyama
Hokkaido Research Center
Forestry and Forest Products Research Institute
7 Hitsujigaoka, Toyohira-ku, Sapporo 062 Japan
Phone +81-11-851-4131

[Total Budget for FY1993-1995]

14,401,000 Yen (FY1995 4,827,000 Yen)

[Abstract]

　The effects of manganese(Mn) toxicity on photosynthesis of tree species in northern Japan representing different successional traits were examined. We sampled Betula ermanii and Alnus hirsuta as early success ional species, Ulmus davidiana var. japonica as mid successional species, and Acer mono as late success ional species. Seedlings were grown hydroponically in the solution containing nutrients and different concentrations of Mn(1, 10, 50, 100mgL^-1) for 50 days. Based on the gas exchange measurements, Mn accumulation in leaves resulted in the decline of RuBP carboxylase activity and the rate of RuBP regeneration but effected less on the maximum efficiency of photochemistry in all plants. Based on these effects on photosynthesis, early successional species of Betula ermanii and Alnus hirsuta are suggested to have more tolerant capacity to excess Mn accumulation in leaves.

Abbreviations: PPFD - photosynthetic photon flux density, Rubisco - ribulose-1,5-bisphosphate carboxylase/oxygenase, RuBP - ribulose-1,5-bisphosphate

[Key Words]

Carboxylation Efficiency, Net Photosynthesis, Quantum Yield, RuBP Regeneration