不同埋藏深度对白花鬼针草、假臭草和胜红蓟种子出苗及生长的影响

为了解菊科入侵植物种子出苗和幼苗生长对埋藏深度的适应机制,通过砂培法研究菊科种子出苗和幼苗生长,比较分析不同埋藏深度下(0、0.5、1.0、2.0、3.0 cm)3种入侵植物种子白花鬼针草(Bidens alba)、假臭草(Praxelis clematidea)和胜红蓟(Ageratum conyzoides)的出苗率、出苗速率和出土时间等参数的差异,探究菊科入侵植物种子出苗和幼苗生长对埋藏深度的响应。结果表明:随着埋藏深度的增加,3种入侵植物种子出苗率和出苗速率均极显著降低(p0.01),出土时间则随着埋藏深度的增加均有不同程度增长,埋藏深度0~1.0 cm、0~0.5 cm和0分别为白花鬼针草、假臭草和胜红蓟种子较适出苗环境;在幼苗生长实验中,随着埋藏深度的增加,白花鬼针草和假臭草幼苗的根长、鲜重呈先上升后下降的趋势,茎长呈下降趋势,较适宜白花鬼针草和假臭草幼苗生长的埋藏深度为0~1.0 cm;胜红蓟幼苗随着埋藏深度的增加,其幼苗的根长、茎长、鲜重均呈下降趋势,较适宜胜红蓟幼苗生长的埋藏深度为0~0.5 cm。3种入侵植物对埋藏深度的耐受能力依次为:白花鬼针草假臭草胜红蓟。结果表明,农耕深度分别为:白花鬼针草2.0 cm,假臭草1.0 cm,胜红蓟0.5 cm。

Effects of Different Seeding Depths on Seedling Emergence and Growth of Bidens alba,Praxelis clematidea and Ageratum conyzoides

In order to know the adaptation mechanism of seedling emergence and growth of invasive Asteraceae plants to seeding depth,three invasive Asteraceae plants,Bidens alba,Praxelis clematidea and Ageratum conyzoides,were sand cultured at the respective depths of 0,0.5,1.0,2.0 and 3.0 cm to compare their differences in seedling emergence percentage,rate and time to explore the response of their seedling emergence and growth to seeding depth.The results showed that seedling emergence percentage and rate of the three invasive plants decreased significantly with the increase of seeding depth (p＜0.01),but the seedling emergence time increased to varying degrees.The optimal seeding depths for seed emergence of B.alba,P clematidea and A.conyzoides were 0 ～0.5 cm,0 ～0.5 cm and 0 cm,respectively.In the seedling growth experiment,B.alba and P.clematidea increased first and then decreased their root length and fresh weight with the increase of seeding depth,and their stem length decreased with the increase of seeding depth.They had a better seedling growth when seeded at the depth of 0～ 1.0 cm.A.conyzoides showed a lower root and stem length and a lower fresh weight with the increase of seeding depth,and it grew better at the seeding depth of 0～0.5 cm.The ability to resist seeding depth of the three invasive plants is in the order of B.alba＞P.clematidea＞A.conyzoides.The results showed that the depth of farming was more than 2.0 cm for B.alba,more than 1.0 cm for P.clematidea,and more than 0.5 cm for A.conyzoides.