COMPARISON OF THE ENERGY EFFICIENCY OF PHOTOSYNTHESIS IN PLANTS - SIMILARITY OF SHADE-REQUIRING SPECIES TO HIGH-YIELDING CULTIVARS

Wild shade-requiring and light-requiring species, light-adapted and sh ade-adapted phenotypes of the same species, as well as wheat, radish, and amaranth cultivars different in productivities were studied. Energ y efficiency of photosynthesis (EEP) was calculated from characteristi cs of light-induced changes in the yield of the delayed fluorescence o f chlorophyll, and expressed as a fraction of thylakoid membrane poten tial utilized in dark reactions of photosynthesis. EEP was reliably (P > 95%) higher in shade-requiring species and shade phenotypes, than i n light-loving species and light phenotypes (on average, 0.73 and 0.61 , respectively). In the three groups of crop plants, a higher EEP was found in high-yield varieties (0.76 and 0.71 in wheat; 0.87 and 0.76 i n radish; and 0.79 and 0.65 in amaranth, for low-and high-yield cultiv ars, respectively). Characteristics of the light-induced changes in de layed fluorescence yield in shade-tolerant plants were shown to be sim ilar to those in high-yield plants. Apparently, the changes in photosy nthetic apparatus brought about by selection for high productivity are similar to those associated with plant adaptation to low light intens ities.