Studies On The Allelopathy And The Identification Of Allelopathical Substance Of Thymus Vulgaris Primula.L

The thyme (Thymus vulgaris), which would soon widely used as Landscape plants, their natural growth might reflect their allelopathical potential. The aqueous leachates, root exudates and oil essence from thyme stem, leaf were conducted according to the releasing routes of plant allelochemicals in nature conditions, which had an obvious effect to the four receptor plants of Raphanus sativus L. radish,Achillea millefolium,Chrysanthemum boreale Makino and Veronica didyma Tenore using the bioassay method in lab. And the main compounds of them were studied with GC-MC and PIT, giving some theory basis on exploitingscientifically and dispose reasonably. The main results were showed as follows.1. The effect to seed germinationThe germination of the four receptor plants was all inhibitated by the aqueous leachates, root exudates and volatile from thyme stem and leaf.The best inhibitation effect of the aqueous leachates and root exudates was all at the highest concentration (1: 1). The percentage comparison of seedling germination among the receptor plants in respective were 55.2% and 88.7% in Raphanus sativus L. radish, 74.3% and 64.0% in Achillea millefolium, 84.5% and42.7% in Chrysanthemum boreale Maldno, and 76.1%and56.0% in Veronica didyma Tenore. Except Raphanus sativus L. radish, the weakest effect of inhabitation was at the concentration of 1: 10 in other three ones, especially Chrysanthemum boreale Makino. Therefore, the effect to the other three ones became weaker when the concentration reduced. The sequence of inhabitation effect from high to low was carrot, Achillea millefolium, Veronica didyma Tenore, Chrysanthemum boreale Makino. On the contray, the inhabitation effect of root exudates was stronger with the higher concentration, weaker with the lower one. The sequence of inhibitation effect on the receptor germination from high to low was Chrysanthemum boreale Makino, Veronica didyma Tenore, Achillea millefolium and Raphanus sativus L. radish, wheras, the sequence of inhabitation effect on the receptor germination speed from high to low was Veronica didyma Tenore, Chrysanthemum boreale Makino, Achillea millefoliumand Raphanus sativus L. radish.However, the effect of volatile from the thyme on the germination of receptor seeds were different from the comparison. Compared with the ordinary plant, the germination percentage of seeds of Raphanus sativus L. radish, Achillea m illefolium, Chrysanthemum boreale Makino, Veronica didyma Tenore were 57%,60%,63%,63% correspondingly.The sequence of inhabitation effect on germination from high to low was Raphanus sativus L. radish, Achillea millefolium, Chrysanthemum boreale Makino and Veronica didyma Tenore; and the sequence of inhabitation effect on germination speed from high to low was Raphanus sativus L. radish, Achillea millefolium, Veronica didyma Tenore and Chrysanthemum boreale Makino.2. The effect to the growth of seedlingThe effect of the aqueous leachates, root exudates and volatile on the germination of seedlings were different in different plants, and different spots in the same one. The effect on the root length was more obvious than on the seedling altitude. Meanwhile, the allelopathy also manifested the concentration.The seedling altitude of Raphanus sativus L. radishwas decreased at the middle concentration of aqueous leachates, in conversely, increased by the highest and lowest ones. All of the four concentrations increased the seedling altitude of Achillea millefolium, but decreased the Chrysanthemum boreale Makino and Veronica didyma Tenore. The high concentration of root exudates increased the seedling growth of Achillea millefolium, wheras, decreased all the seedling altitude of the four receptor plants above all. Besides, it was obscure in Chrysanthemum boreale Makino. The seedling altitude of the Raphanus sativus L. radish,Chrysanthemum boreale Makino and Veronica didyma Tenore were all decreased by the volatile from the thyme, but increased in Achillea millefolium. Therefore, the comparison between the treated and untreated was clear. The results were as follows:The four receptor plants were all influnced by the aqueous leachates from the thyme. The sequence of effect on seedling altitude of them was Veronica didyma Tenore (RI-0.49), Achillea millefolium (RI 0.38),Chrysanthemum boreale Makino (RI-0.33) and Raphanus sativus L. radish (RI 0.21); And the effect on root length was Achillea millefolium (RI 0.63), Chrysanthemum boreale Makino (RI -0.61), Veronica didyma Tenore (R1-0.47) and Raphanus sativus L. radish(R1-0.15).The four receptor plants were all influnced by the root exudates from the thyme. The sequence of effect on seedling altitude of them was Veronica didyma Tenore (RI-0.33), Achillea millefolium (RI 0.26), Chrysanthemum boreale Makino (RI-0.12) and Raphanus sativus L. radish (RI-0.11); And the effect on root length was Achillea millefolium (RI0.45), Veronica didyma Tenore, Chrysanthemum boreale Makino (RI-0.32) and Raphanus sativus L. radish (RI-0.28).The four receptor plants were all influnced by the volatile from the thyme. The sequence of effect on seedling altitude of them was Veronica didyma Tenore (RI -0.47), Chrysanthemum borealeMakino (RI-0.36), Achilleamillefolium (RI0.34) and Raphanus sativus L. radish (RI-0.22); And the effect on root length was Veronica didyma Tenore (R1-0.47 ), Chrysanthemum boreale Makino (RI-0.36), Raphanus sativus L. radish (RI-0.42) andAchillea millefolium (RI0.09).3 The compounds of allelopathical substanceThe three fractions were analysed by GC—MS. The result showed that there were allelopathical substance, such as phenol and Se, having founded in former studies. According to the analysis of the component of aqueous leachates, it indicated that the Thymol was the main one. The Terpinen,cis-3-Hexenal,Anisole, 2-isopropyl-5-methyl were contained in large number in volatile from thyme, the same as phenol. And the analysis report of the root exudates, was only taken to reference because of weak signal. In brief, the results showed that these compounds such as Thymol,Terpinen,Borneol, (1S, 2R, 4S)-(-)-,Anisole, 2-isopropy1-5-methyl,Cubebene,o-Cymene,2-Carene,Myrcene,Camphene,1R-Pinene and so on, play an important role in thyme alMopathy.There are allelopathical substance distributing in the aqueous leachates, root exudates and volatile from thyme, which has a choice on different plants, and correspondingly the allelopathy either increase or decrease the seedling growth of the receptor plant. The routs of rain -eclucidation and oil-essence are the main form of allelopathy. Therefore, if disposed with other plant suitably, they would help to make an ideal plant landscape in the future.