ALLELOPATHY OF DIFFERENT AQUEOUS LEAF EXTRACTS ON THE SEED GERMINATION AND SEEDLING GROWTH OF PENNISETUM ALOPECUROIDES (L.) SPRENG.

Allelopathic chemicals are different in coniferous and broadleaved plants, so the impacts on other plants are also different. In this paper, the effect of aqueous leaf extracts from Metasequoia glytostroboides Hu et Cheng, Cedrus deodara (Roxb.) G. Don 'Aurea', Liquidambar formosana Hance, Platanus acerifolia (Aiton) Willd. and a mixture of coniferous and broadleaf trees on seed germination and seedling growth of Pennisetum alopecuroides (L.) Spreng. At the same concentration (50 gDW/L) was investigated using an indoor filter paper culture dish method. The results were evaluated using the Response Index (RI) and the Synthesis Effect Index (SE). The results showed that: (1) The leaf extract of P. acerifolia (Aiton) Willd. promoted the germination of P. alopecuroides (L.) Spreng. seeds, and inhibited the growth of P. alopecuroides (L.) Spreng. seedlings. The metabolism of M. glytostroboides Hu et Cheng, C. deodara (Roxb.) G. Don 'Aurea' and L. formosana Hance leaf extracts inhibited the seed germination and seedling growth of P. alopecuroides (L.) Spreng. The allelopathic inhibitory effects were: M. glytostroboides Hu et Cheng > C. deodara (Roxb.) G. Don 'Aurea' > L. formosana Hance. (2) In this study, the single leaf extract of the coniferous trees (M. glytostroboides Hu et Cheng and C. deodara (Roxb.) G. Don 'Aurea') and the broadleaved trees (L. formosana Hance and P. acerifolia (Aiton) Willd.) did not show significant differences in the allelopathic effect on P. alopecuroides (L.) Spreng. Seeds. (3) Compared with their corresponding single leaf extracts, all of the coniferous-broadleaved mixed extract treatments showed neutralization effects on the allelopathic effects of P. alopecuroides (L.) Spreng. Namely, one single leaf extract > coniferous-broadleaved mixed extract > another single leaf extract. The results could provide a scientific basis for the management of urban forests and ecosystems.