Allelopathic effects of Caragana intermedia on monocot and dicot plant species and identification of allelochemicals

We studied, the effects of aqueous extracts Caragana intermedia roots on germination and seedling growth of 4-crops: Dicots [Sophora alopecuroides L., Mehlotus officinalis L], Monocots [Elymus dahuricus Turcz. and Sorghum sudanense Piper.]. The aqueous extract inhibited the germination of dicotyledonous species and the effect was concentration dependent. In monocots, aqeous extracts of high concentrations (2.0, 5.0 and 10.0%) reduced the germination, while low concentrations (0.5 and 1.0%) were stimulatory. The 10.0% aqueous extract significantly inhibited the germination of dicotyledonous species. In monocotyledonous species, the inhibitory effects were observed during the early stages, but not in the final stages of test period. At 10.0% aqueous extract, both dicotyledonous species produced significantly shorter roots. GC-MS (gas chromatography mass-spectrometry) analysis of the extracts resulted in > 21 peaks. The major constituents were D-myo-Inositol and 2,3-Butanediol, whose relative content was 80.2%. The 2,3-Butanediol, L (+)-lactic acid and DL-homoserine can be considered as the allelochemicals for Medicago sativa Linn.