Effect of soil temperature on light-thermal characteristics of birch seedlings Betula pendula

The effect of the soil temperatures (15, 20 and 25 °C) on light-thermal characteristics on intact two-year birch seedlings was studied in the controlled environment in a pre-planned multifactor experiment. The greatest possible maximum of net-photosynthesis in birch seedlings was reached at soil temperature of 15 °C, air temperature of 20,6 °C, and light intensity of 34,6 klux. At two other soil temperatures, the potential maximum of the net-photosynthesis was about 10 % lower and was achieved at a higher level of light intensity and lower level of air temperature.