不同前茬作物下苜蓿地土壤杂草种子库的特征

为了探讨前茬作物对紫花苜蓿（Medicago sative）地杂草种子库的影响，采用诱萌法，于2010年在内蒙古林西县研究青贮玉米(Zea mays)、尖叶胡枝子(Lespedeza hedysaroides)和沙打旺(Astragalus huangheensis)3种前茬作物下生长第2年的紫花苜蓿地土壤杂草种子库的特征。结果表明，前茬为青贮玉米时苜蓿地杂草主要是马齿苋(Portulaca oleracea)和反枝苋(Amaranthus retroflexus)，前茬为尖叶胡枝子时主要是马齿苋、刺藜(Chenopodium aristatum)和反枝苋，前茬为沙打旺时主要是刺藜和反枝苋；前茬作物为尖叶胡枝子时，土壤杂草种子库的密度与其他两种前茬作物之间存在显著差异（P＜0.05）；土壤种子库杂草的种子主要集中在0～5 cm的土壤耕作层，下层分布较少。

Characteristics of soil weed seed bank of alfalfa fields among different fore crops

To study the effects of fore crops on the characteristics of soil weed seed bank of alfalfa fields at second growing years,three different fore crops,which were Zea Mays,Lespedeza hedysaroides and Astragalus adsurgens,were designed by the inducing germination method.The results showed that,when the fore crop was Z.mays,the mainly weed of alfalfa field were Portulaca oleracea and Amaranthus retroflexus;When the fore crop was L.hedysaroides,the mainly weed were P.olerecea,Chenopodium aristatum and A.retroflexus;When the fore crop was A.adsurgens,the mainly weed were C.aristatum and A.sretroflexus.Density of soil seed bank had significant difference between L.hedysaroides and the other two fore crops(P<0.05);Weed seeds of the soil seed bank mainly concentrated in 0-5 cm soil layer and the distribution of deep level was very little.