Die variabilität der größe der photosyntheseeinheit bei licht- und schattenpflanzen

Abstract

Plants of Sinapis alba were cultivated under two different light intensities. The rate of photosynthesis is highly dependent on the light intensity. Under strong light conditions the rate of photosynthesis is three times higher than under weak light conditions. Changing the plants from weak to strong light conditions a period of 5 days is necessary until the rate of photosynthesis is fully adapted to strong light. At the first day special phenomena are found. Plants grown under strong light conditions show a ratio of chlorophyll a: b of 3.6. In weak light the ratio is only 3.0. The ratio of chlorophylls to Carotinoids is 3.7 under strong light and 4.8 under weak light conditions. The lipophilic plastid quinones (plastoquinone, plasto-quinol, α-tocopherol, α-tocoquinone) are essentially higher concentrated under strong light conditions. The different rate of photosynthesis seems to correspond with the variability of the photo-synthetic unit. Under strong light conditions smaller chlorophyll antennae are formed while their number as well as the number of electron transport chains is highly increased. Under strong light conditions we find about 4 molecules PQ and 10 molecules PQH2 for one electron transport system. Under weak light conditions 9 molecules PQ and 7 molecules PQH2 are present.