Abstract: In order to make a reasonable recovery of nitrogen for oilseed rape with dual purpose for vegetable and oil,field trial was conducted to study the effect of topdressing of nitrogen in the period of stem clipped on the yield and N use efficiency. The results showed that topdressing of nitrogen before stem clipped（Q）,topdressing of nitrogen after stem clipped（H）,topdressing of nitrogen before and after stem clipped（QH） could improve the yield of oilseed rape significantly by 6.3%~10.8% compared with that of the treatment without topdressing（CK）. The yield of the QH treatment was increased by 4.2% significantly compared with that of the Q treatment. The application of topdressing of nitrogen in the period of stem clipped could improve the pod number by 18.4%~31.9% significantly,and had no obvious effect on the height,primary branch number,secondary branch number,seeds per pod and thousand-seed weight. The results of nutrient uptakes showed that topdressing of nitrogen before and after stem clipped could improve the N uptakes. The N uptakes of the Q treatment,H treatment and QH treatment were increased by 3.2%,17.7%（P<0.05） and 15.5%（P<0.05） respectively compared to that of the treatment of CK. Significant difference was found in added N use efficiency among different treatments. The N use efficiency of the H treatment was highest,which increased by 4.5 times compared to that of the Q treatment.

Key words: oilseed rape with dual purpose for vegetable and oil, stem clipped, nitrogen, yield