[Effects of different rice farming systems on paddy field weed community]

Taking the paddy fields planted with glutinous rice and hybrid rice in the traditional agricultural region in Congjiang County of Guizhou Province as the case, and by using semi-experiment combined with random sampling investigation, this paper studied the characteristics of weed community in the paddy fields under rice monoculture (R), rice-fish culture (R-F), and rice-fish-duck culture (R-F-D). Under the three rice farming systems, glutinous rice had higher capability in inhibiting weeds, compared with hybrid rice. Farming system R-F-D decreased the weed density significantly, with the control effect on Monochoia vaginalis and Rotala indica being 100%. The overall weed-inhibiting effect of R-F-D was significantly higher than that of the other farming systems. Under R-F-D, the species richness and Shannon diversity index of weed community decreased markedly, while the Pielou evenness index increased, indicating that the species composition of weed community changed greatly, and the occurrence of native dominant weed species decreased. It was concluded that R-F-D was a feasible farming system for the control of paddy field weed community.