小蓬草水浸液对2种花卉种子萌发及幼苗生长的化感作用

Allelopathic Effects of Aqueous Extract from Conyza canadensis onSeed Germination and Seedling Growth of Two Herbaceous Flower Species

为揭示入侵杂草与草本花卉之间的竞争关系,以入侵植物小蓬草为供体材料,常用的花卉波斯菊、观赏油菜为受体材料,研究了小蓬草根、叶水浸提液对受体植物种子萌发、幼苗生长、抗氧化酶活性(SOD、POD和CAT)以及丙二醛(MDA)含量的化感效应差异。结果表明,(1)小蓬草浸提液对受体植物的种子萌发均具有显著化感效应,基本表现为“低促高抑”的趋势,且波斯菊、观赏油菜的种子萌发率在根、叶浸提液浓度为25 g/L时最高,在浸提液浓度为100 g/L时最低。(2)小蓬草浸提液对受体植物幼苗上下胚轴生长具有“低促高抑”的浓度效应,且浓度越大抑制作用越显著。(3)在小蓬草根、叶浸提液处理下,观赏油菜的SOD和POD活性大多显著高于对照,波斯菊SOD和POD活性则大多显著低于对照;波斯菊、观赏油菜CAT活性整体呈先缓慢升高后降低的趋势。(4)波斯菊幼苗MDA含量随小蓬草根、叶浸提液浓度的增加均呈现逐渐升高的趋势,并大多高于对照水平,而观赏油菜幼苗MDA含量随着根浸提液浓度增加而逐渐升高,却随着叶浸提液浓度的增加而降低,但大多显著低于对照水平。研究发现,小蓬草浸提液对2种花卉种子萌发和幼苗生长均表现出“低促高抑”化感作用,且综合效应强弱表现为观赏油菜大于波斯菊,根浸提液处理大于叶浸提液。

In order to reveal the competitive relationship between invasive weeds and herbaceous flowers,we used the invasive plant Conyza canadensis as the donor material,and the commonly used flowers Cosmos bipinnatus and Brassica juncea L.as the receptor materials.The allelopathic effects of the extracts of the roots and leaves of C.canadensis on the seed germination,seedling growth,antioxidant enzyme activities(SOD,POD and CAT)and malondialdehyde(MDA)content of the receptor plants were studied.The results showed that,(1)the extracts of C.canadensis had significant allelopathic effects on the seed germination and seedling growth of the receptor plants,which basically showed the trend of‘low promotion and high inhibition’.The seed germination rate of C.bipinnatus and B.juncea was the highest when the concentration of root and leaf of C. canadensis was 25 g/L, and the lowest when the concentration ofextract was 100 g/L. (2) The extract of C. canadensis had a concentration effect of ‘low promotion andhigh inhibition’on the growth of upper and lower hypocotyls of seedlings, and the greater the concentration,the more significant the inhibition. (3) The activities of superoxide dismutase (SOD) and peroxidase(POD) in rapeseed were significantly higher than those in the control, while the activities of SOD and PODin C. bipinnatus were significantly lower than those in the control. The catalase (CAT) activity of C. bipinnataand B. juncea showed a trend of slowly increasing first and then decreasing. (4) The MDA contentof C. bipinnata seedlings increased gradually with the increase of the concentration of root and leafextract, and most of them were higher than the control level. The MDA content of B. juncea seedlingsincreased gradually with the increase of the concentration of root extract, and decreased with the increaseof the concentration of leaf extract, but most of them were significantly lower than the control level. Thestudy found that the extract of C. canadensis showed the allelopathic effect of ‘low promotion and high inhibition’on the seed germination and seedling growth of the two kinds of flowers. The comprehensiveeffect was that the B. juncea was greater than the C. bipinnatus, and the root extract was greater thanthe leaf extract.