Analysis of Medicinal Resources of Tree Peony Bark and Seed and Seedling Propagation Techniques

Medicinal Resources of Tree Peony Bark, Seed and Seedling Propagation

(I) Propagation Methods and Materials

The propagation methods of tree peony are divided into sexual propagation and asexual propagation. Different propagation methods use different germplasm materials.

(1) Sexual propagation uses seeds as germplasm material.

(2) Asexual propagation includes division, grafting, cuttings, layering and tissue culture, etc. ① Division uses the multiple small tree peony plants divided from a tree peony as germplasm material; ② Grafting uses 6-10 cm one-year-old vigorous branches growing from the lower part of the tree peony, with healthy terminal buds and 2-3 lateral buds as scions for germplasm material; ③ Cuttings use current-year soil sprout branches growing from the root area of the tree peony, or stems that are strong, with plump terminal buds and free of pests and diseases as cuttings; ④ Layering uses tree peony branches as germplasm material; ⑤ Tissue culture uses tree peony embryos, flower buds, stem tips, young leaves, etc. as material.

(II) Propagation Techniques

Sexual propagation of tree peony, also called seed propagation, is a propagation method that uses seeds formed by fertilized ovules during the sexual development stage of tree peony for propagation. Asexual propagation includes cuttings, division, grafting, layering, tissue culture and other methods. The specific propagation methods are listed below.

(2) Grafting. Tree peony grafting should be carried out after early autumn and before Double Ninth Festival, with the most suitable time around White Dew, when the grafting survival rate reaches as high as 80%-90%. For grafting, herbaceous peony roots or tree peony seedlings can be selected as rootstock, and 6-10 cm one-year-old vigorous branches growing from the lower part of the tree peony, with healthy terminal buds and 2-3 lateral buds, can be selected as scions. Tree peony grafting usually adopts the forms of branch grafting and bud grafting. Branch grafting can be further divided into dug grafting and in-situ grafting.

① Branch grafting

·Dug grafting:Herbaceous peony roots or tree peony roots can be selected as rootstock. First use a knife to cut both sides symmetrically into a wedge shape at 2-3 cm from the lower end of the scion, at the same time cut the top of the rootstock flat, then from one side cut downward with one knife to make a split with a depth of 2/3 of the rootstock diameter and a length of 3-4 cm. Then insert the scion into the split so that the cambium layers of both are aligned and closely connected; bind tightly with hemp rope or plastic film strips, and smear the interface with clay slurry, then plant.

In-situ grafting:Cut off all branches above 5-6 cm of the aboveground part of the original tree peony plant; the remaining method is the same as dug grafting.

② Bud grafting: generally carried out from June to July, when the survival rate is relatively high. Select seedling tree peony plants as rootstock, and use plump and full buds on current-year branches as scions. Make a horizontal cut about 2 cm below the axillary bud of the plant, and perform ring peeling or cut out a square bud as the grafting bud; then cut a surface of the same size on a rootstock branch of the same thickness, then attach the grafting bud to the cut surface and bind tightly with hemp rope or plastic film strips.

③ Suitable time for grafting tree peony: Tree peony grafting depends on specific temperature and humidity. Grafting after early autumn and before Double Ninth Festival, especially around White Dew, has the highest survival rate.

(3) Cutting propagation. Around the Autumn Equinox, cut two-year-old thick and full branches into 10-15 cm long cuttings, treat with 500-1000 mg/L gibberellin (GA3), and insert into sandy loam soil with appropriate humidity. If selecting current-year vigorous sprout branches, then around September cut them into or treat with 500 mg/L indoleacetic acid (IAA), and insert 2/3 of the branches into sandy loam soil with appropriate humidity. If selecting current-year vigorous sprout branches, then around September cut them into cuttings with 2-3 buds, treat with 500 mg/L naphthaleneacetic acid (NAA) or 300 mg/L potassium indolebutyrate (IBA), then insert into a mixed substrate with a sand-to-soil ratio of 1:1, and culture at 18-25°C for 20-30 days to produce adventitious roots.

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