Effect of doubled CO2 on morphology: Inhibition of stomata development in growing birch (Betula platyphylla Suk.) leaves

Abstract

Two-year old birch (Betula platyphylla Suk.) seedlings were grown in climatic chambers for 7 weeks under various conditions: (1) ambient CO2 concentration (350 ppm) and an ordinary nitrogen content in soil (2 mM NH4NO3); (2) ambient CO2 concentration and a high nitrogen rate (16 mM NH4NO3); (3) doubled CO2 concentration (700 ppm) and ordinary nitrogen content, and (4) doubled CO2 concentration and a high nitrogen rate. Doubled CO2 concentration in combination with the high nitrogen rate activated mostly seedling growth, e.g., stem thickening and leaf initiation. In this treatment, the maximum rate of apparent photosynthesis (A max) was twice as high as in control seedlings. At doubled CO2 concentration and ordinary nitrogen content, we observed the phenomenon of stomata absence from the upper leaf surface and doubling their number on the lower surface, whereas, at doubled CO2 concentration and a high nitrogen rate, stomata partition was essentially similar as in control leaves. The conclusion is that, when the balance between CO2 concentration and nitrogen rate is shifted, doubled CO2 concentration exerts a morphotropic effect on differentiation of young epidermal tissue.