Comparative study on photosynthetic pigments of different fall dormancy types of alfalfa in Beijing

The photosynthetic pigments contents in the leaves of four fall dormancystandard America alfalfa varieties at growth period after autumn cutting were determined. The results showed that the chlorophyll and carotenoid of the four alfalfa falldormancy varieties showed an increase to the peak then reduced in the fall growth period. The chlorophyll content of FD5 was higher than the others. This suggested that the half falldormancy type was more adapted to the Beijing climate. The chlorophyll a/b contents of the four varieties were not volatile through the whole fall growing period. And the change regulations of chlorophyll a/b were similar to chlorophyll contents. The carotene contents had order as FD5 FD1 FD11 FD8. Four varieties basically had same leaf photosynthetic pigment absorption spectrum, but the optical density values of FD1 and FD5 were lower than FD8 and FD10 in 440 nm.