MEASUREMENT OF GAS-EXCHANGE IN FABA-BEAN LEAVES (VICIA-FABA L)

By means of gas-exchange measurements (minicuvette system and porometer), photosynthesis and its light dependence was investigated on attached leaves of different varieties of faba beans. The results showed no relevant difference in photosynthetic capacity for the varieties. This is true also for parameters calculated from light dependence, i.e. light compensation point, light saturation, and quantum yield. Generally, the light compensation point lay under 50 mu E PAR/m(2)/s and light saturation was reached at about 1400 mu E PAR/m(2)/s. Photosynthesis was strongly dependent on leaf age and difference in photosynthetic capacity due to different varieties could be excluded as an essential reason for different rates of flowers dropping and pod dropping in faba beans.