Abstract: Abstract：In the present study，three-year old‘Changfu 2’apple trees grafted on dwarfing interstock
（M26）were respectively planted with different planting depth in Yangling，combined with the
investigation of Fengxiang，Yongshou and Pucheng，Shaanxi Province. Then these trees were used to
investigate the effects of the planting depth on root system growth，root hormone，fruit yields and quality.
The results showed that，in the treatment with 15 cm planting depth of dwarfing interstock，fine roots
（＜ 2 mm）mainly distributed in the soil layer of 0–40 cm，and the number of fine roots was 13.6%–
41.5% more than other treatments，total roots number was 18.2%–33.3% more than other treatments，the
root dry weight was 11.2%–68.4% of that in other treatments. Moreover，15 cm treatment showed more
competitive advantage，i.e.，the quantity of fruit yields，single fruit weight，soluble solid contents，fruit
hardness，fruit coloring and the titratable acid. Furthermore，the 15 cm planting depth had highest level ofIAA，ZR and GA contents，but the contents of ABA was at the lowest level. the ratio of （IAA + GA + ZR）/ ABA
was at the peak，which helps to stimulate the growth of roots. These results indicate that 15 cm planting
depth of dwarfing interstock can promote the growth of root，increase fine and total root numbers so that
apple trees obtain more nutrition by root and have good fruit quality.

Key words: apple, interstock, planting depth, distribution of root system, hormone, yield, quality