Abstract: A field experiment was conducted during 2002—2007 to evaluate effects of various drip fertigation frequencies（4 times/year，10 times/year，16 times/year）on tree growth，fruit yield and quality of Trovita sweet orange（Citrus sinensis Osbeck）on‘Carrizo’citrange [Poncirus trifoliata（L.）Raf.] × Citrus sinensis Osbeck] rootstock（planted in 2001）in calcareous purple soil in Zhongxian County of Chongqing. The control trees were fertilized（10 times/year）by broadcast application. The results showed that tree trunk circumference，tree height and canopy diameter did not show significant response to fertigation frequency；And no significant difference existed between fertigation treatments and control for tree growth. However，fertigation treatments showed significant effects on increasing fruit yield with 29.4%–36.5% more accumulative yield than the control，but high fertigation frequency did not increase fruit yield. No significant effects was observed for fertigation on fruit quality. It is recommended that citrus growing in calcareous purple soil should be drip fertigated 4 times a year.

Key words: Citrus sinensis Osbeck, Trovita sweet orange, drip fertigation, tree growth, fruit