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 ma jalis, 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 prom oted photosynthesis in the leaves of the two sun-type plants more stro ngly 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 enhanci ng 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 reactio ns in leaves of sun-type plants.