Abstract: Controlled release nitrogen fertilizers(CRNF) are physically prepared from the granules of the soluble nitrogen fertilizers by coating them with film-forming materials to reduce their dissolution rate.These fertilizers are made to release nitrogen nutrient gradually to synchronize with the nitrogen requirement of crop plants during different growth stages.This study quantified the effect of CRNF on root morphological and physiological characteristics during late growth stages of hybrid rice,and lipid peroxidative products,active oxygen scavenging enzymes in root system during the root senescence process of hybrid rice.The results showed that the CRNF could increase the root dry weight,root length,and root length density,while the root radius became smaller during later growth stages of hybrid rice.At the meantime,the CRNF(decreased) the MDA contents but increased active oxygen scavenging enzyme activities.The CRNF could also increase the activity of SOD,POD and CAT during root senescence process,and the gradually release of nitrogen nutrient from the CRNF could decrease the production and accumulation of active oxygen in the root system,thus enhance the activities of active oxygen scavenging enzymes.Therefore,the CRNF could significantly retard the senescence and decline of nitrogen absorbing capacity of the root systems through regulating nitrogen release rate from CRNF during late growth stages of(hybrid) rice.