On the basis of values from literature it was established that photosynthetically used radiation (PUR) amounts to 6 % of absorbed radiant energy in cabbage (producer of high yields), 3.5 % in sugar beet leaves, and 2.6 % in tobacco leaves. PUR of these species did not depend on irradiance in a wide range from 22 to 287 W m-2.
On the basis of literature and my calculations it was established that a chlorophyll (Chl) particle anchored with a phytol chain to the thylakoid membrane takes up about 1 nm2 of the surface area. At an irradiance of 287 W m-2 the leaves of cabbage seedlings become saturated with photosynthetically active radiation (PAR) thus reaching the maximum photosynthetic rate of 100 µg(C) m-2 s-1, that is 5 CO2 molecules per 1 nm2 per second, and the maximum power with which the Chl particle supplies the process of photosynthesis is 15 aJ.