Detailed Explanation of Cutting Propagation Techniques for Japanese Late Cherry during Full Bloom

  Cherries are brightly colored and very magnificent, making them important ornamental flowering trees for gardens. They are suitable for group planting in courtyards or in front of buildings, and can also be used as street trees along paths. Japanese late cherry has large flowers, double petals, vivid colors, fragrant scent, and a long flowering period, making it an excellent variety among cherries. Propagating Japanese late cherry by grafting results in slow seedling formation and cumbersome operations, while using hardwood cutting techniques makes rooting very difficult. Through continuous exploration and experimentation, a fast and efficient method for propagating Japanese late cherry was finally found: using vermiculite as the substrate and inserting one-year-old branches with young shoots during the full bloom period.

  Propagating Japanese late cherry by inserting one-year-old branches with young shoots during the full bloom period has the characteristics of fast seedling formation, simple operation, easy rooting, and a high survival rate. The key technical points for cutting propagation of Japanese late cherry during full bloom are introduced as follows:

  [Substrate]

  Expanded vermiculite is used as the substrate, maintaining a pH of 6.2. The author found that at night, the temperature of the vermiculite seedbed was 2°C to 3°C higher than that of a soil bed, while at noon the temperature was 1°C to 2°C lower than that of a soil bed. This indicates that the vermiculite seedbed has a small day-night temperature difference and greater accumulated heat, with good insulation effect, which is beneficial to root growth. In production, granular vermiculite is preferred, as it has good permeability and is favorable for rooting. Powdery vermiculite is sticky and has poor air permeability. When raising seedlings, do not mix soil into the vermiculite, otherwise root rot easily occurs.

  [Cutting Time]

  It can be carried out from April to July. The experimental records are shown in the table below: From the table above, it can be seen that the survival rate of cuttings during the full bloom period of cherry is the highest, because at this time the plant is in its peak physiological activity period and is easy to root. For cuttings taken on April 28, after transplanting on June 28 there was no recovery period; 5 days later, new buds of 0.5 cm sprouted, and after 4 years of cultivation, the tree was full of flowers.

  [Selection and Treatment of Cuttings]

  1. Selection of cuttings: Cut 15 cm long branches from vigorous mother trees, with the upper end bearing new shoots of the current year and the lower end being one-year-old branches. The leaves on the new shoots can produce nutrients, and the one-year-old branches have already become lignified, making them easy to survive as cuttings. Experiments have shown that the vast majority of 3- to 6-year-old branches used as cuttings rot and die. It can thus be seen that the survival rate of cuttings is related to age; the older the branch, the weaker its physiological function and the harder it is to survive.

  2. Treatment of cuttings: Before inserting, remove the leaves on the portion to be inserted into the vermiculite, keeping the upper leaves. Dip the cuttings quickly in 1000 ppm naphthaleneacetic acid. That is: insert the base of the cutting 2 to 3 cm into a 1000 ppm naphthaleneacetic acid solution, then immediately take it out for insertion, dipping and inserting as you go.

  [Cutting Method]

  Use bricks to build a seedbed 20 cm high and 1 m wide (length depends on the number of cuttings). Spread 2 to 3 cm of river sand on the bottom layer of the seedbed, then fill in 15 cm of vermiculite. Install one centrifugal spray nozzle every 1 m, or connect a sprayer wand to a tap water pipe for misting. In early May, set up a shade shed, use branches as a fence around it to block wind, and to keep warm and moist, a plastic shed cover can also be set up over the seedbed. Insert the cuttings vertically in rows into the vermiculite, with a plant spacing of 2 cm and a row spacing of 4 cm, and water thoroughly after insertion. A cutting depth of 6 to 8 cm is appropriate, because according to observation, the temperature at a depth of 5 cm is on average 2°C to 4°C higher than at a depth of 10 cm, and most callus tissue and adventitious roots form at 6 to 8 cm.

  [Post-Cutting Management]

  Frequent misting to keep the leaf surface moist is the key to survival. At noon when the temperature is high, the number of mistings should be even greater and the intervals should be shorter. At night and in the morning when there is dew, misting may be omitted. The relative air humidity should be maintained above 90%, and the vermiculite moisture should be maintained at 58% to 60%. Before rooting, this standard must be reached, and special attention should be paid before callus tissue forms. In early May, a shade shed should be set up to prevent exposure to the scorching sun. When the temperature inside the plastic shed exceeds 35°C, open both ends of the shed for ventilation, and after the temperature drops to 27°C, seal it again. If the weather is too hot, water can be sprayed outside the plastic shed, which can both lower the temperature and avoid excessive water spraying causing too high a moisture content in the vermiculite.

  [Transplanting Time and Method]

  Transplant promptly when the root system of the cuttings grows to 6 to 8 cm. If transplanted too late, the root system of the cuttings will turn brown and rot, and the leaves will gradually turn yellow. This is because vermiculite can only keep warm, retain moisture, and provide aeration, playing a role in promoting rooting, but it has no nutrients to supply continued growth of the cuttings. In addition, cuttings with few roots or only callus tissue and no roots should remain in the seedbed and be transplanted after the roots have grown well.

  Creating an environment suitable for the continued growth of cutting seedlings is the key to ensuring survival after transplanting. Choose a fertile plot that does not accumulate water, make a north-south oriented bed 8 m long and 0.3 m wide, mix in sandy loam and deep plow 30 cm, then cover with 2 cm of sandy loam. Level the bed surface, plant one row per bed, with a plant spacing of 30 cm. Place the root system of the cutting together with the surrounding vermiculite into the planting hole, and fill the hole with sandy soil. Do not press hard, to prevent breaking the tender roots. Immediately irrigate the bed surface thoroughly, and set up a 1.2 m high shade shed above it. Mist 2 to 3 times a day to keep the leaf surface moist, and water the ground frequently, alternating between dry and wet. Seedlings transplanted in this way do not undergo a recovery period, have a high survival rate, and grow normally.