Rooting Effect of Softwood of Betula alnoides Under the Influence of Age of Mother Tree, Plant Growth Regulation

In order to solve the problem of low cutting roting rate of Betula alnoides, the shoots of B. alnoides of different ages were treated with different plant growth regulations. Indolobyric acid, naphthoacetic acid and indolobyric acid + naphthoacetic acid were set as different plant growth regulations, and 1.0 g/L, 0.5 g/L and 0.1 g/L were set as 3 factors and 3 levels orthogonal tests with different concentration gradients. The results showed that the age of the mother tree, the type of the plant growth regulation and the concentration of the plant growth regulations all had significant difference on the rooting rate of the cutting of B. alnoides in southwest China, which were the main factors affecting the rooting rate of B. alnoides cuttings. The order of the influence degree was the type of the plant growth regulation, the age of the mother tree and the concentration of the plant growth regulation. When the mother trees were 1-year-old and treated with 1.0 g/L indolobutyric acid, B. alnoides had the best cutting rooting effect, and the rooting rate reached 79%.