紫花苜蓿土壤浸提液对蜀葵的化感作用

为探究紫花苜蓿对蜀葵种子萌发和生长的化感作用，采取了紫花苜蓿根际及距离根际20、40、60 cm处表层5~10 cm的土壤，采用高效液相色谱法（HPLC）检测土壤浸提液（分别表示为R、D20、D40、D60）中5种有机酸类化感物质的含量。采用生物检测方法分析测定了土壤浸提液对蜀葵种子萌发的影响，并通过盆栽试验测定了紫花苜蓿与蜀葵间作条件下蜀葵叶绿素、丙二醛（MDA）、可溶性蛋白及生物量等生理生态学指标。结果表明： 5种有机酸在紫花苜蓿根际的含量最高，随着与根际距离的增加有机酸含量逐渐减少；R处理下，蜀葵发芽率和发芽指数比对照（蒸馏水）分别降低6.23%和31.32%，根长和苗长则与对照相比分别显著减少了56.11%和48.94%。盆栽实验结果表明，紫花苜蓿和蜀葵间作对蜀葵地上和地下生物量均产生明显抑制作用，与单种时相比分别减少8.01%和23.99%；间作使蜀葵叶绿素含量降低、MDA和可溶性蛋白含量升高。研究表明，紫花苜蓿对蜀葵有明显的化感作用，种植时不宜过密，应至少保持间距60 cm。

Allelopathy of Medicago sativa L. soil extracts on Althaea rosea Cavan

In order to investigate the allelopathy of alfalfa(Medicago sativa L.) on seed germination and growth of hollyhock(Althaea rosea Cavan), the surface layer soil(5~10 cm) at the alfalfa rhizosphere(R) and 20, 40 cm, and 60 cm away from the alfalfa rhizosphere(D20, D40, D60, respectively) were collected. The contents of allelochemicals in soil extracts of these samples were detected by high performance liquid chromatography(HPLC). The effects of different soil extracts on the seed germination of hollyhock were studied using a bioassay method, and physiological and ecological indexes such as biomass, chlorophyll, malondialdehyde(MDA), and soluble sugar of hollyhock under intercropping conditions were determined by pot experiment. The results showed that the contents of five organic acids were highest at the alfalfa rhizosphere, and decreased gradually with increasing distance. Compared with the control, under R treatment, the germination percentage and germination index decreased by 6.23% and 31.32%, respectively; The root length and seedling length decreased by 56.11% and 48.94%, respectively. The results of the pot experiment showed that the intercropping of alfalfa and hollyhock significantly inhibited the aboveground and underground biomass of the hollyhock by 8.01% and 23.99%, respectively, which could also decrease the chlorophyll content, and increase the MDA content and soluble protein content. The study indicates that alfalfa has an obvious allelopathic effect on hollyhock, and should not be planted too densely, keeping at least 60 cm spacing.