Detailed Explanation of Softwood Cutting Propagation Techniques for Cherry Blossom
Cherry blossom (Prunus serrulata Lindl.) is a deciduous tree of the Rosaceae family, with a height of 5-25 cm, bearing corymbose or racemose inflorescences composed of 3-5 flowers, with white or pink petals, single or double, flowers and leaves emerging together or flowers before leaves, blooming in April-May. When spring arrives and flowers bloom, the trees are covered in blossoms competing in beauty, with brightly colored, fragrant, elegant and dignified flowers, making it a famous ornamental flowering tree for landscaping.
Cherry blossoms are usually propagated mainly by grafting, mostly using single-petaled cherry blossoms or cherry as rootstock, performed by cut grafting or cleft grafting before early spring flowering, and there are very few reports on the application of cutting propagation. In recent years, our experiments on softwood cutting propagation of cherry blossoms have shown that within 25 days after cutting, the average rooting rate was above 95%, with a maximum of 20 roots per plant, and most were cortex-type roots, with some callus-type roots. The transplanting survival rate was above 90%. The techniques are described below.
1 Collection and Treatment of Cuttings
From early to mid-June to early to mid-September, collect semi-lignified branches grown in the current year, cut them into 10-15 cm long segments, keep 2-3 leaves at the top of each segment, remove the remaining leaves together with their petioles, and make a flat cut at the lower end of the cutting with a sharp blade, requiring a smooth cut surface. Bundle the prepared cuttings into small bundles of 50 or 100 pieces, and in a cool, moist place, soak the base of the cuttings about 3-4 cm in a solution of ABT Rooting Powder No. 1 (developed by the ABT Research Center of the Chinese Academy of Forestry) at a concentration of 50 mg/L for 5-8 h, or in a solution at a concentration of 100 mg/L for 2-4 h.
2 Cutting Method and Post-Cutting Management
2.1 Cutting Bed Setup
Choose a cool, well-drained location to build a small plastic arched shed 1.2-1.5 m wide and 5.0-6.0 m long, with an arch height of 70-90 cm. First dig down 25 cm at the bottom, then lay about 10 cm thick cinder, and on top lay about 10 cm thick expanded perlite or green sand as the cutting substrate, and water thoroughly.
2.2 Cutting
Insert the cuttings into the cutting bed at a plant spacing of 3 cm and a row spacing of 5 cm (with the leaves of adjacent cuttings not overlapping). When cutting, first make holes with a short wooden peg slightly thicker than the cutting, then place the cutting into the hole, firm the substrate around the cutting so that the substrate is in close contact with the cutting. The cutting depth is 4-5 cm.
2.3 Post-Cutting Management
Immediately after cutting, sprinkle thoroughly with clean water and cover the shed film tightly, maintaining relative humidity above 95%. Thereafter, spray an appropriate amount of clean water once every morning. The temperature inside the arched shed should be maintained at around 30°C; if it exceeds 35°C, water may be sprinkled to cool it down. The substrate temperature should preferably be around 25°C. In the early stage after cutting, the amount of water sprinkled should be relatively larger, then gradually reduced. When the cuttings begin to root (generally about 15 days after cutting), ventilation may be carried out appropriately in the morning and evening, then gradually increase the ventilation amount and extend the ventilation time. When the roots of the cuttings reach 3-5 cm in length and each cutting has 3-5 roots, they can be transplanted.
3 Transplanting
Before transplanting, gradually open the shed film, harden the seedlings for about 7 days, and reduce the amount of water sprinkled. When transplanting, directly move the hardened cutting seedlings into the field, water thoroughly immediately, and shade with a shade net for a few days, avoiding exposure to strong sunlight. Alternatively, first move them into nutrient pots (the culture soil should have good permeability), then place them in a small arched shed, water thoroughly, cover with shed film, keep moist and shaded for a few days. At first, ventilate in the morning and evening every day, gradually increase the ventilation amount after 2-3 days, open the shed film after 10 days, remove the shading material, and after another 4-5 days of hardening, they can be moved into the field.