Studies On The Separation And Identification Of Potential Allelochemicals Of Trifolium Repens L.

Allelopathy was a new cross-discipline, the theory and practice on which can bring sustaining development in agriculture or forest and help to protect natural resources. As a kind of important grazing and lawn, White clover (Trifolium repens L.) natural growth might reflect their allelopathical potential. This paper studied the allelopathic effect of stem and leaf exudate, root exudate and volatile from stem and leaf of white clover on Abutilon theophrasti and Echinochloa crusgalli using the bioassay method in lab. And the main compounds of them were studied with column chromatography and GC-MS. The main results were as follow:1. Abutilon theophrasti and Echinochloa crusgalli were measured for evaluating the allelopathic potentional of stem and leaf exudate, root exudate and volatile from stem and leaf of white clover by the way of indoor Petri dish bioassay, the results showed that they all had allelopathy on seed germination and seedling growth of receptor plants, and allelopathy of aqueous extracts was the most strong part. Allelopathy of aqueous extracts and root exudate showed the concentration effects that test receptor plants were promoted at lowest concentration while inhibited at highest concentration. Such as under concentration 120 g/L , 30 g/L , 7.5 g/L of stem and leaf exudate, RI of root length of Echinochloa crusgalli was -0.81, -0.28, and +0.10 respectively; under concentration 270 g/L , 90 g/L , 30 g/L of root exudate, RI of germination rate of Abutilon theophrasti was -0.19, -0.07and +0.04 respectively.2. The main compounds of aqueous extracts, root exudate and volatile from stem and leaf of white clover were studied with GC-MS. The result indicated that aqueous extracts mainly include phenol, organic acid, ester, ketone, hydrocarbon and alcohol. And the main components were cyclobutene, 2-propenylidene-, 2, 3-dimethylphenol, BHT, dibenzofuran, n-hexadecanoic acid, eicosanoic acid, ethyl ester, homovanillic acid and heptadecane, 8-methyl-, et al. Root exudate mainly include ester, hydrocarbon, alcohol, phenol, organic acidand aldehyde. The main components of root exudate were dibutyl phthalate, [1, 4, 7] trioxonane, 3-phenyl-2-butanol, octane, ethanol, 2-butoxy-, 1, 3-cyclopentadiene, 5-isopropylidene-, p-xylene and benzyl benzoate, et al. Volatile mainly include olefin, ester, aether, hydrocarbon, organic acid and alcohol. The main components of volatile were cis-3-hexenyl acetate, 4-methyl-1,3-pentadiene,ethyl vinyl ether, acetone, cis-3-hexen-1-ol, isobutylene oxide, 5-isopropylidene-, 5-hydroxy-4-methyl-6-heptenyl-3-one and propanedioic acid,2,2-dihydroxy-, et al. Some of these compounds were reported as alleochemicals, such as n-hexadecanoic acid, o-phthalic acid and diisooctyl phthalate, et al. , Some of these compounds were not, such as 2, 3-dimethylphenol, dibenzofuran, 3-phenyl-2-butanol and cis-3-hexenyl acetate et al.3. The effects of four kinds of potential allelochemicals (2, 3-dimethylphenol, limonene,β-caryophyllene and cis-3-hexenyl acetate) were studied. The results showed that 2, 3-dimethylphenol had stronger alleopathy, under concentrations 5×10-3mol/L, RI of Stem length and Fresh weight of Echinochloa crusgalli were -1 and -0.99 respectively, which indiecated inhinbition notable. Coupled with concentrations reduce, the inhinbition became weaken, and at the lowest concentrations, it became auxo-action, such as under concentrations 5×10-3mol/L, 2, 3-dimethylphenol had weaker auxo-action on stem length of Abutilon theophrasti, which RI was 0.04. Cis-3-hexenyl acetate, limonene, andβ-caryophyllene had alleopathy on receptor plants, of which the inhinbition of cis-3-hexenyl acetate were stronger. Volatile of cis-3-hexenyl acetate totally inhibit seed germination and seedling growth of Abutilon theophrasti, all of inhibition ratio of test specification were100%. But limonene andβ-caryophyllene had complicated effect on receptor plants, inhibition ratio of stem length and root length of Echinochloa crusgall were 28.2% and -10.1% respectively treated by limonene, and inhibition ratio of root length and seed germinaition of Abutilon theophrasti were 30.6% and -9.8% respectively treated byβ-caryophyllene.4. In addition, the author studied the cocktail effect of limonene,β-caryophyllene and cis-3-hexenyl acetate. The result indicated that different mixture had different effect on different receptor plants or different test specification. In sum, the effect of their mixture mainly showed addition reaction and rivalry, synergized action was not significant.