小飞蓬对三种杂草种子萌发和幼苗生长的化感作用

以稗草[Echinochloa crusgalli (L.) Beauv.]、鬼针草(Bidens pilosa L.)、含羞草(Mimosa pudica L.)3种杂草种子为受体,以小飞蓬[Conyza canadensis (L.) Cronq.]全株为供体,采用培养皿滤纸培养法研究小飞蓬水提取液的乙酸乙酯、正丁醇和水萃取物对受体植物种子萌发和幼苗生长的化感作用.结果表明,小飞蓬的乙酸乙酯萃取物强烈抑制稗草和鬼针草的种子萌发和幼苗生长,且抑制效应随萃取物浓度的升高而提高,高浓度的乙酸乙酯萃取物对含羞草的种子萌发和幼苗生长抑制作用明显.乙酸乙酯萃取物浓度为0.5 mg/mL时,其对3种杂草幼苗的根长、茎长和鲜重的抑制作用与对照组比较就有显著差异.乙酸乙酯萃取物浓度为2.0 mg/mL时,其对稗草和鬼针草根长的化感效应指数(RI)值均为-1.00,对茎长的RI值分别为-0.97和-0.78;二者种子的萌发率平均值分别为3.3％和2.2％.小飞蓬的正丁醇萃取物抑制3种杂草的种子萌发和幼苗生长,但比乙酸乙酯萃取物的抑制作用弱.高浓度小飞蓬水萃取物强烈促进3种杂草的幼苗生长.说明小飞蓬水提取液中的除草活性物质可能存在于乙酸乙酯和正丁醇萃取物中.

Allelopathy of Conyza canadensis on Seed Germination and Seedling Growth of Three Types of Weed

Ethyl acetate,butanol and water extracts from Conyza canadensis were used to test their allelopathic effects on the seed germination and seedling growth of three types of weed [Echinochloa crusgalli(L.) Beauv,Bidens pilosa L,and Mimosa pudica L].The results showed that ethyl acetate extract could strongly inhibited the seed germination and seedling growth of E.crusgalli and B.pilosa.The inhibition increased with the increasing concentration of extract.High concentration of the ethyl acetate extract could effectively inhibit the seed germination and seedling growth of M.pudica L.When the concentration of ethyl acetate reached 0.5 mg/mL,significant differences of seedlings of the 3 species emerged on their root length,stem length and fresh weight compared with the control.When the concentration of ethyl acetate reached 2.0 mg/mL,the respond indexes of allelopathy(RI) of the root length of E.crusgalli and B.pilosa were both-1.00;while the RI of the stem length was-0.97 and-0.78 respectively.The average germination rate of two seeds was 3.3% and 2.2% respectively.The butanol extract could inhibit the seed germination and seedling growth of three weeds,but its inhibition was weaker than the ethyl acetate extract.High concentration of the aqueous extract could effectively promote seedling growth of three weeds.It could be concluded that herbicidal active substances from C.canadensis were probably existing in extracts of ethyl acetate.