多裂骆驼蓬对紫花苜蓿化感作用的生理生化机理

采用室内生物测定方法研究了多裂骆驼蓬水浸液对紫花苜蓿的化感作用及其作用机理,并用试管法对其水浸液的有机成分进行了定性分析。结果表明,多裂骆驼蓬水浸液含有生物碱、酚类、有机酸、还原糖和多糖类、皂甙、甾体、氨基酸,不含蛋白质和鞣质。经水浸液处理后的紫花苜蓿萌发种子呼吸速率、淀粉酶和蛋白酶活性受抑,种子萌发率及幼苗根长、苗高和鲜重下降,并随处理浓度提高而降低。幼苗根系活力和叶绿素、可溶性蛋白质、核酸含量随水浸液浓度的提高而降低,蛋白酶和核糖核酸酶活性及超氧阴离子（O2ˉ）、H2O2和丙二醛（MDA）含量则增加,超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）活性呈先升后降变化。由此表明,雨水淋溶是多裂骆驼蓬向环境释放化感物质的途径之一,化感作用在增强其生态竞争力和扩大种群中起着重要的作用。

Physiological and Biochemical Mechanism of Allelopathy of Peganum multisectum Bobr on Alfalfa

Indoor bioassay was adopted to study allelopathic actions and allelopathy mechanisms of aqueous extract from Peganum multisectum Bobr on alfalfa(Medicago sativa L.),and its organic composition were qulitalive analyzed by test tube method.The results showed that it contains akaloids,phenols,organic acids,reducing sugars and polysaccharides,saponins,sterols and amino acids,but not tannins and protein.When alfalfa were treated with aqueous extract from P.multisectum,the respiratory rate,activities of amylase and proteinase during seed germination and germination rate,root length,shoot height and fresh weight of seedlings were inhibited and this inhibition become stronger as the concentration of aqueous extract increased.With the increase of concentration of aqueous extract from Peganum multisectum increased,root vigor,the contents of chlorophyll,soluble protein and nucleic acid in roots and shoots of alfalfa seedlings decreased,while the activities of protease and nuclease,the contents of O2-,H2O2 and malondiadehyde(MDA) increased,the activities of superoxide dismutase(SOD),catalase(CAT) and peroxidase(POD) first increased and then decreased.Results indicated that rain eluviation was one of the means by which P.multisectum released allelochemicals,the allelopathy of the leaching might play an important role in enhancing the competitive ability of the species.