Detailed Explanation of Key Techniques for Autumn and Winter Cuttings of Prunus x cistena

    Prunus x cistena (prunsxcistenena) is a deciduous small tree of the Rosaceae family and Prunus genus, reaching about 2.5 m in height. Its leaves are long-ovate or ovate-lanceolate, 4-8 cm long. The leaf surface is red or purple, with the underside even redder, and the tips of new leaves are bright purplish-red, making it very attractive for landscaping and beautification. The flowers are pale pink, blooming from April to May. It prefers light and a warm, humid climate, and has low soil requirements. It is cold-tolerant and drought-tolerant, with a high transplant survival rate, and tolerates pruning well; it can be shaped into balls or planted in masses as color bands. The wood is bright purplish-red. It leafs out from mid-April to early May and drops its leaves in late November, remaining purplish-red from bud break to leaf fall. It is a world-famous foliage tree species, commonly used for planting along streets, in parks and courtyards.

Prunus x cistena is generally propagated by grafting, but this method has high costs, slow propagation, easy variation, and a short lifespan. In recent years, the author conducted technical experiments on autumn and winter hardwood cuttings of Prunus x cistena. The results showed that this method has low cost and fast speed, with a cutting survival rate of over 95%.

The key techniques for autumn and winter hardwood cuttings are briefly introduced as follows:

1. Cutting selection: For cutting preparation, select vigorous 2-3 year old plants as mother trees. After leaf fall in late autumn, cut disease-free and pest-free current-year branches from the mother trees. Alternatively, in combination with shaping and pruning, use the cut thick, plump-budded branches free of pests, diseases and mechanical damage as cuttings. Cut the selected cuttings into 25-45 cm segments, bundle them in groups of 100-150, and store them buried in wet sand, one layer of sand and one layer of cuttings, and seal well to prevent bud sprouting from excessive temperature or water loss from air exposure.

2. Nursery site selection and preparation: For nursery site selection and land preparation, choose a site with convenient drainage, irrigation and transportation. The soil should be deep, fertile, loose sandy loam. Before land preparation, evenly spread 1.2-1.5 tonnes of decomposed farmyard manure per mu (1 mu = 1/15 ha), and spread 1.6 kg of 50% carbendazim into the soil for soil sterilization and disinfection; then spread 4 kg of 50% zinc-phosphide granules to kill underground pests. Then deep plow, harrow finely, level the land, remove weeds, waste agricultural film and other debris, and make beds. Prunus x cistena prefers a humid environment but does not tolerate waterlogging, so it should be planted in a high, dry place, and never in a low-lying area. The bed length depends on the nursery site; the bed width is 1-1.5 m and the height is 30 cm. Leave a ditch between beds, 40 cm wide and 30 cm deep. After making the beds, press lightly, harrow and level the bed surface, and prepare for cutting.

3. Cutting time: mid-November to mid-December.

4. Cutting method: Before cutting, first remove thin and weak branches and water-loss shriveled parts from branches just cut or stored in wet sand. Then, from bottom to top, cut the long branches into cuttings 15-18 cm long with 5-8 buds. Cut the lower end of the cutting near a bud into a smooth horseshoe-shaped slant to increase the contact area between the cambium and the soil, which helps rooting. Cut the upper end of the cutting flat 0.8-1 cm from the bud eye. After cutting, immediately soak the lower slanted end in clean water for 15-20 hours so the cuttings fully absorb water. Place the base of the prepared cuttings into a 10-fold mixed solution of 10% B-indoleacetic acid and B-indolebutyric acid, dip for 12 seconds, then remove and air-dry before inserting to promote rooting. Insert the cuttings into the soil with the slanted end down, at a spacing of 6 cm x 8 cm, with the upper bud exposed 0.5-1 cm above the ground. Immediately after cutting, irrigate with water until fully soaked through, which helps the cuttings bond tightly with the soil. After the ground surface dries slightly, cover with double-layer thin plastic film to preserve moisture. At the same time, build a 1 m high thick plastic small arch shed on the bed surface with the same width as the bed. Straw curtains or reed curtains can be laid over it to help keep warm and protect against cold.

5. Management of cutting seedlings: After cutting, shading must be done well, with a light intensity of about 30% being suitable. If the seedbed has plastic film and a small arch shed, it can be kept for a long time without watering; if the soil under the plastic film is dry, irrigate once along the bed ditch. The temperature is best controlled between 16-25°C, and the humidity at about 80%. When the minimum temperature drops to minus 5°C, add straw curtains outside the arch shed for freeze protection and insulation; after the minimum temperature rises to 0°C, uncover the straw curtains during the day and put them down at night; when the minimum temperature reaches above 5°C, open the arch shed during the day and ventilate appropriately to prevent high-temperature scorching of seedlings. To prevent mold on the substrate and cuttings, regularly spray antifungal agents such as carbendazim and thiophanate-methyl. In early March, when seedlings are 3-5 cm tall, the root system is basically formed, and young roots can grow to 1-3 cm. Uncover the plastic film during the day for ventilation and hardening of seedlings, gradually increasing ventilation as the seedlings grow. From mid-to-late March to early April, pay attention to keeping the seedbed moist. In mid-April, remove the shed film and fertilize, weed and water in time. At this point, transplant into pots, preferably into simple thin-walled soft plastic pots. The soil in the pots should be compacted so that the soil forms a clod when planting out. Shade and water, place under a shade shed, and plant out after 1 week.

6. Management of transplanted seedlings: In late April, choose a rainy day or after 4 p.m. on a sunny day for transplanting. Before lifting seedlings, fill the plastic pots with enough water to help reduce root damage when lifting, and the roots should be kept with a soil ball. At transplanting, the spacing is 30 cm x 50 cm. Before transplanting, apply 4-5 tonnes of decomposed farmyard manure and 50 kg of 15% ternary compound fertilizer per mu, then deep plow and harrow finely before transplanting. After planting, water thoroughly. Keep the nursery land neither dry nor overly wet, and strengthen the control of pests, diseases and weeds. In early June, before rainy days or before irrigation when the soil is dry, spread 25 kg of urea per mu to promote seedling growth. During the growing season, appropriate topdressing should also be applied. Apply a nitrogen, phosphorus and potassium compound fertilizer once each in early spring and early summer, and apply a layer of barnyard manure again in late autumn. For newly planted seedlings and seedlings with poor growth due to nutrient deficiency, foliar fertilization can be carried out at a concentration of 0.5%, sprayed in the early morning or evening. It should not be done at midday when light is strong, nor before or after rain. The number of sprays should preferably be 3 times, with an interval of 10-15 days. In the same year, transplanted seedlings can reach an average height of 1.2-1.5 m and a ground diameter of 1-1.5 cm.