LIGHT RESPONSE CURVES OF PHOTOSYNTHESIS IN LEAVES OF SUN-TYPE AND SHADE-TYPE PLANTS GROWN IN BLUE OR RED-LIGHT

Light saturation curves after growth in blue light (BL) or red light (RL) were studied in leaves of the shade-type C-3-plant, Convallaria majalis, and two sun-type plant species, the C-3-plant, Hordeum vulgare, and the C-4-plant, Zea mays. The photosynthetic activity of BL leaves of C. majalis was found to be 1.5 times higher than that of RL leaves at all the irradiances examined. Unlike the shade-type plant, BL promoted photosynthesis in the leaves of the two sun-type plants more strongly for saturating irradiance levels (activities 1.4-1.5 times higher than in RL) than for the linear part of the light saturation curve (1.1-1.2 times higher than in RL). The results indicate that the enhancing action of BL on the different parts of the photosynthetic apparatus depends on the ecological type of plant: in contrast with shade-type plants, BL promotes mainly the activity of dark photosynthetic reactions in leaves of sun-type plants.