Photosynthesis, leaf area and productivity of five poplar clones during their establishment year

摘要

Abstract: The stem volume and biomass (stem + branches) production, net photosynthesis of mature leaves and leaf area production of 5 poplar (Populus) clones, Populus trichocarpa x deltoides (Raspalje and Beaupre), Populus x euramericana (Robusta) and P trichocarpa (Columbia River and Fritzi Pauley), were studied during the first year of growth in an experimental high density plantation (15 600 plants ha-1). Significant differences were found in volume production, woody biomass production, total leaf area and net photosynthesis. Above-ground biomass production was 3.5 times higher in Raspalje than in Robusta. The best performing clones (Raspalje, Beaupre) were those with large leaves, high leaf area index and high photosynethetic rates. A positive relationship between leaf photosynthetic capacity and above-ground biomass production was also noted for 4 of the 5 clones. The euramerican clone Robusta was an exception, showing high photosynthetic rates, but low biomass production. This discrepancy was mainly due to the lower leaf area of this clone, and possibly also due to a larger carbon allocation to below-ground biomass (Barigah, 1991). The root/shoot ratios at the end of the first season in the clones Raspalje and Robusta were 1.23 and 1.79, respectively.