GAS-EXCHANGE OF PLANT-LEAVES UNDER LIGHT AND PHOTORESPIRATION DURING THE TRANSITION FROM LIGHT TO DARKNESS AS STUDIED FROM 2 GASES (CO2 AND O2) .1. RATIO OF OXYGEN AND CARBON-DIOXIDE IN GAS-EXCHANGE UNDER LIGHT AND RESPIRATION DURING THE TRANSITION FROM LIGHT TO DARKNESS IN ONTOGENY OF THE SOURCE FUNCTION OF LEAVES IN C3 AND C4 PLANTS

We conducted synchronous measurements of O2 and CO2 exchange in source leaves of C3 and C4 plants. It is demonstrated that the coefficient of gas exchange for leaves under light (O2/CO2) is equal to one under conditions of coordination of physiological processes (plant growth and leaf exposure at an irradiation density of adaptation of 200 W.m-2 PAR). In respiration during the transition from light to darkness, significant changes of the CO2/O2 ratio - from 4.8 to 0.65 - are detected in ontogenesis of the source function of leaves in C3 and C4 Plants. The obtained results are discussed from the viewpoint of succession of functional tasks in ontogenesis of source leaves and interaction of glycolysis, the Krebs cycle, and the mitochondrial ETC.