Scientific publications

A comparative estimation of CO₂ gas exchange in leaves of common (silver) birch (Betula pendula var. pendula) and Karelian birch (Betula pendula var. сarelica) was carried out at different levels of mineral nutrition. After an additional fertilizing, saplings growing in pots under high insolation showed the 1.4-fold increase in average rates of CO₂ gas exchange. Dark respiration in common birch increased 2.3-fold and became almost twice that of Karelian birch. Except for this parameter, no significant differences between the two forms of birch were revealed. Fertilized saplings adapted to low levels of solar radiation showed significant differences in the parameters of light response curves: the light compensation point and the saturation constant. Lower values of these parameters in Karelian birch indicate its effective utilization of low values of solar radiation, allowing it to survive under the conditions of strong shadow.