Abstract: Previous studies have proved that root system development,which is directly related to fertilizer management,significantly affects the lodging resistance and grain yield of rice.However,no report regarding the influence of controlled-release fertilizers(CRF) on rice root-system development has been found so far.Pot trials with 6 fertilization treatments and cylinder trials with 5 fertilization treatments were conducted using 3 CRFs as experiment materials in 2003 to investigate the effects of single application of controlled-release fertilizer on root system morphologic development of and lodging resistance of rice.Result showed that two controlled-release fertilizer treatments with single basal application of Nongke controlled-release fertilizer(BNCRF) and bulk blend fertilizer with resin coated urea(BRCU),increased root dry weight by 26.56%—35.24% and 17.99%—37.35% respectively compared to 4 split application of Nongke rice-specific fertilizer(SNRSF),14.57%—23.24% and 7.52%—24.34% respectively compared with single application of rice-specific fertilizer BNRSF.In addition,BNCRF and BRCU increased root volume by 13.94%—41.77% and 19.02%—30.42% compared to SNRSF,3.99%—26.54% and 9.40%—16.40% compared to BNRSF,respectively.In comparison with the SNRSF,the proportion of deep root distribution,root depth index and diameter of basal stem in BNCRF and BRCU treatment are much higher.The effects of single basal application of controlled-release fertilizer with MgNH4PO4 coated(BLCRF) were not as significant as BNCRF and BRCU on benefiting the development of root system and stem probably due to its lower K rate.However,BLCRF still increased dry root weight by 10.16%—16.84% compared to SNRSF with high K rate.It was concluded that single basal application of CRFs significantly promoted the development of rice root system,obviously multiplied root mass in deep layer,thus improved lodging resistance.