Objectives The effects of soil application of different doses of vitamin B6 on the fruit quality were studied in order to provide a new method to improve fruit quality of Fuji.

Methods The doses of vitamin B6 of 0 (control), 3, 5 and 7 g per plant were added into soil 60 cm away from the Fuji apple trunk, and two application tine of April and June were set in 2013 and 2014. Contents of nitrogen, phosphorus, potassium, soluble solids, vitamin C and aroma components of the fruits were determined when the fruits were ripe.

Results The total nitrogen, phosphorus and potassium contents in treatment of 7 g plant in April were the highest of 2013 and 2014, which were to significantly higher than the control. The quality indicators of 7 g per plant in both April and June treatments were significantly higher than those of the control in both 2013 and 2014, and the difference in the quality indicators between the two application time were significant (except the hardness indicator of 2014). In 2013 and 2014, the relative content of total esters in 7 g per plant treatment was significantly higher than that of the control. The relative content of ethyl-2-methyl butyrate in esters was significantly higher than that of the control (except 3 g per plant in April 2013 and 7 g per plant in June 2014). The content of ethyl-2-methyl butyrate of 7 g per plant in April was the highest in the current year, and the differences with other treatments were significant. The relative content of ethyl butyrate, ethyl caproate, butyl 2-methyl butyrate, isopropyl 2-methyl butyrate in treatment of 7 g per plant in both application times in 2013 and 2014 were significantly higher than that of the control, and also significantly higher than those of other does treatments.

Conclusions Application of vitamin B6 7 g/plant in April performs best in improving the fruit nutritional quality and single fruit weight, but application of B6 7 g/plant in June peforms best in improving the quality of fruit aroma. Therefore the doses of vitamin B6 of 5 g or 7 g/plant is recommanded under the conditions of this study.