DOC《分类号》

相同浓度不同密度下,表现为随着密度的增加抑制作用逐渐减弱,消失,并逐渐转化为促进作用.当密度为15株/盆,核桃醌浓度为20?g?mL-

1、2?g?mL-1时幼苗各生长指标均高于对照,即在此条件下有利于黄芩幼苗的生长. 关键词:核桃;

黄芩;

化感作用;

气体挥发物;

浸提液;

核桃醌 Effects of allelopathic substances from Walnut on Baicalensis Master Candiadate: Pan Dan (Silviculture) Directed by Professor Zhai Mingpu ABSTRACT Walnut ( Juglans regia L. ) is a kind of allelopathic tree. Choosing an appropriate associate specie is very important for walnut comprehensive management patterns. Scutellaria baicalensis georgi is one of the Third-grade State wild medicinal plants. It has been in lack because of the serious damage and the improperate cultivation systems. In nowadays, Walnut has been successfully cultivated with many kinds of medicinal plants , and the pattern of Walnut and Baicalensis seems to be the best one. In this paper, we designed a pot experiment, used dynamic head-space and GC-MS methods, and probed into the effects of the Walnut allelochemicals on Baicalensis through volatile gas, eluviation and root exudates . Through this experiment, we also got several important conclusions: (1) The components of volatiles from Walnut were varied with seasons. Firstly, according to the number of volatiles, the order from high to low was: November >

May >

August. Secondly, based on the contents of terpenoid volatiles, the order from high to low was: August >

May >

November. The results showed that there were more terpenoids in August than May and November. In other words, walnut might have stronger potential effects on other plants nearby in August. The result indicated that the main component of volatile gas was monoterpene. It was different from the results tested by former researchers. (2) Limonene was the main terpenoid in volatile gas. It enhanced seed germination of Baicalensis when concentration was low and it inhibited the same action when concentration was high. With the effect of Limonene, the mean time of germination was longer than that of control. And the higher the concentration, the stronger the inhibition. (3) The aqueous extract from Walnut leaves and roots had effects on Baicalensis seedlings. First, the aqueous extract with low concentration greatly promoted the seedlings'

growth, and the promotion effect increased gradually with the increasing concentration. But, this kind of effect decreased when the concentration reached a certain point, and also, it changed into inhibiting effect if the concentration kept increasing . Second, the aqueous extract had positive effects on height, root length, biomass, the photosynthetic rate, transpiration rate, stomatal conductance, chlorophyll content, fluorescence characteristics and nutrient content of seedlings when the concentration was low, and it brought negative effects when the concentration was high. The initial aqueous extract concentration which resulted in inhibition e........