Study On Allelopathy Of Compositae Extracts On Microcystis Aeruginosa

As the development of eutrophication, microcystis aeruginosa is spread around the world flooding, although a number of studies is on algae treatment, the traditional method of controlling algae still have certain disadvantages. As the algal allelopathy research carried out, some scholars believe that the use of plant allelopathy may be an effective way to control algae; mostly aquatic plants present study the influence of algae as the research object, but few studies on land plants. The purpose of this study was to explore the land plants on algae by allelopathic effects of new ways to combat Microcystis.Asteraceae (Compositae) is one of the largest families of angiosperms, is also the chemical composition of the largest, most complex, one of the most evolved families. There are about 1,000 genera,25000-30000 species in the world, of about 200 genera in China. The studies have been carried out are mainly on their domestic and bactericidal activity, the toxicity or its chemical constituents, but so far on the role of Compositae algal allelopathy is rarely reported.This paper chooses three common Compositae:Chrysanthemum nankingense, Erigeron annuns, Cronyza Canadensis, to study the allelopathic effects of the extracts from the plants’leaves and stems on the growth of Microcystis aeruginosa. In the mean time, we also tested the effects on chlorophyll fluorescence parameters of M icrocystis aeruginosa by AquaPen-CAP-C100. The main parameters were determined: maximum fluorescence of PSⅡ(Fm), maximum quantum yield of PSⅡ(Fv/Fm), the actual activities of PSⅡ(Yield), photochemical quenching (Qp), non-photochemical quenching(NPQ). The main results are as follows:1. The influence of the extracts from Chrysanthemum nankingense to Microcystis aeruginosa displayed promotion under the low concentration but inhibition under the high concentration. The extractions of different medias had different effects on Microcystis aeruginosa. The inhibition of the concentration 10g/L alcohol extracts from Chrysanthemum nankingense leaves was the best, under the treatment, the photosynthesis action of the algae cells is inhibited obviously. Fm, Fv/Fm, Qp, NPQ values were significantly reduced.2. The influence of the extracts from Erigeron annuns to Microcystis aeruginosa displayed promotion under the low concentration but inhibition under the high concentration. The maximum inhibition rate of the aquatic extracts from Erigeron annuns leaves was 63.55%, the aquatic extracts from stems was 50%, and the alcohol extracts from stems was 44.95%, but the alcohol extracts from leaves was the highest, above 95%, Fm, Fv / Fm, Qp, NPQ was significantly decreased, we could find that electron transport、energy conversion、utilization decreased, photosynthesis of algal cells was inhibited, PSⅡsystem was damaged.3. The influence of the extracts from Cronyza Canadensis to Microcystis aeruginosa displayed inhibition. The inhibition rates of the aquatic extracts from Cronyza Canadensis leaves increased with the concentration increasing. The highest rate is 82.55% under the treatment of the concentration 10g/L, the fluorescence parameters was obviously decreased; but the inhibition rate of the alcohol extracts from leaves was lower, the highest was 22.99%.