Abstract: 【Objective】 The characters and effects on weed community caused by different long-term fertilization managements was evaluated in rice-wheat rotation field in Taihu Lake region for the purpose of bio-diversity protection, crop yield increase and noxious weeds decrease. 【Method】 Inorganic fertilizer treatments were selected as follows: CK (no fertilizer), N (N fertilizer), NK (N plus P fertilizer), NPK (N plus P and K fertilizer), NP (N plus P fertilizer) and PK (P plus K fertilizer). Weed density and community surveys were conducted, and bio-diversity indices were also calculated, including diversity index (Shannon-H’), evenness index (Pielou-EJ), and richness index (Margalef-DMG). At the same time, principal component analysis (PCA) and regression analysis were executed to mining the relationship between fertilizer management and weeds.【Result】Total weed density order was NP＞CK＞N＞NK＞NPK, and Lapsana apogonoides, Malachium aquaticum, Beckmannia syzigachne and Vicia sativa were dominant species in Taihu Lake rigion. The biodiversity indices were increased when nitrogen and phosphorus was deficient, and especially, Shannon-H’ index order was CK＞NK＞PK＞N＞NP＞NPK. The eigenvalue of principal components F1 and F2 were 0.498 and 0.235, respectively. L. apogonoides, Geranium carolinianum, Cyperus difformis and B. syzigachne could illustrate more about F1, since the angels were small between F1 and these weeds arrows. The regression coefficients of determination were 0.85, 0.86 (P＜0.05), which analyzed between the value of F1 and soil available-N and Olsen-P, respectively, and there was no significant relationship between F2 and soil nutrient in eigenvalue.【Conclusion】The weed density and dominant species in rice-wheat rotation field were limited by soil nutrient, the biodiversity indices of weed community were higher when soil nutrient was not so sufficient, and weed community was affected sensitively by available-N.

Key words: long-term fertilization , rice-wheat rotation , weed community , biodiversity