箭叶橐吾水溶物对9种牧草种子化感作用研究

研究了青藏高原东部草原毒杂草箭叶橐吾根、叶水溶物对9种牧草(包括与箭叶橐吾同域分布的中华羊茅、大雀麦、垂穗披碱草、早熟禾、羊茅、扁穗冰草、无芒雀麦和异域分布的牧草鸭茅、岷山猫尾草)种子萌发的化感作用。结果表明,水溶物浓度在0.2 g/mL时对垂穗披碱草等7种牧草的萌发率和萌发指数有明显抑制作用,浓度降低,其抑制作用减弱;供体不同部位水溶物的化感效应不同,根的抑制作用大于叶;水溶物对萌发指数的影响大于对萌发率的影响。综合分析箭叶橐吾水溶物对受试牧草化感作用的整体影响显示,9种牧草中,大雀麦、早熟禾和垂穗披碱草受抑制作用明显,对岷山猫尾草作用微弱,而对扁穗冰草和无芒雀麦的种子萌发有一定的促进作用;不同分布区的牧草对箭叶橐吾化感作用的反应无一致性改变。结果显示水雾淋溶是箭叶橐吾化感物质释放的途径之一,化感作用能在箭叶橐吾入侵高寒草场过程及单优势种形成中起一定作用;在人工草场恢复时,应优先选择如岷山猫尾草、扁穗冰草和无芒雀麦等对箭叶橐吾化感作用不敏感的牧草种类。

Allelopathic effects of aqueous extracts from Ligularia sagitta on seed of nine pasture plants

Ligularia sagitta,a noxious weed,distributes widely in psychro-grassland in the east of Qinghai-Tibet plateau of China.The allelopathy of aqueous extracts from roots and leaves of the noxious weed to 9 pasture plants(including 7 species of sympatry and 2 species of allopatric distribution with the weed) was reported in this paper.Results showed that both seed germination rate and germination index of 7 tested plants were inhibited at 0.2 g/mL aqueous extraction of L.sagitta.As concentration decrease,allelopathy intensity weaken.The allelopathy potential of aqueous extracts from different parts of the donor is different.A general inclination is the effect of root extract was more outstanding than that of leaf extract,and seed germination index was more sensitive to the extracts than germination rate.The results of germination index integrates with germination rate influenced by aqueous extracts from roots and leaves of L.sagitta showed that inhibition effect was significant to Poa annua,Bromus magnus and Elymus nutans;feebly to P.pratense and in a way promoted effect to Agropyron cristatum and B.inermis.The response to the weed allelopathy between pasture plants from different distribution areas did not present consistency change.Our results suggest that rain eluviations should be one of the means which the weed releases allelochemicals and allelopathy may play a role during L.sagitta invaded grassland and formation of mono-dominant community.In the term of vegetation restoration of degraded grassland,P.pratense,A.cristatum and B.inermis should be selected preferentially.