The main methods of propagating cut roses are cuttings, grafting, and tissue culture. In production, grafted seedlings are more commonly used. 1. Cutting propagation (1) Softwood cuttings. Automatic intermittent spray cuttings are often used. ① Cutting bed setting. Use bricks to build a ridge-shaped cutting bed with a width of 100-120 cm, a length of 4 meters or 8 meters (depending on the conditions), and a depth of 30 cm. Water supply pipes are installed between the beds, and a sprinkler is installed every 150-200 cm.
The automatic control system is composed of relays, solenoid valves, and electronic leaves. A 12-15 cm thick coal slag layer is placed at the bottom of the cutting bed as a water seepage layer, and a 15-20 cm thick vermiculite layer is placed on top as the cutting medium. ② Selection of rose cuttings From June to October, you can select strong, semi-lignified branches that have flowered but have not yet sprouted axillary buds. Depending on the length of the internodes, cut them into segments of about 10 cm with 2 to 3 buds. The upper cut should be 0.3 to 0.5 cm from the upper bud, and the lower cut should be 1 to 2 mm close to the base of the lower bud, retaining the two leaflets on the upper part. ③ Root promotion treatment and cuttings. Quickly dip the base of the cuttings with 400 mg/kg indolebutyric acid, then cut them with a row spacing of 7 cm and a scion spacing of 2.5 to 4 cm. The relative humidity of the cutting bed surface should be maintained at about 70%, and the average temperature in the cutting bed should be 27 to 28℃. Rooting will occur in 20 to 30 days.
(2) Cuttings with heels. ① Cutting bed preparation. Choose flat, well-drained sandy loam. First, loosen and level the soil. Then create a standard seedbed 1 to 1.3 meters wide and adjustable in length. The bed should be loose and flat. Top it with a 5-centimeter-thick layer of medium-grained river sand, evenly mix in 1/3 of loose loam, and level it. ② Selecting Cuttings. In mid- to late April, select newly emerged, strong shoots 7 to 9 cm in length.
When removing cuttings, break them off. Be sure to include the heel (the meristem at the base of the cambium), as this is crucial for ensuring the survival of the cuttings. To prevent wilting, it’s best to plant cuttings in the cool mornings and evenings, immediately following the cutting. Remove the base leaves before inserting into the soil, leaving as many remaining leaves as possible. Insert the cuttings 1.5 to 2 cm deep into the soil, spacing them so they don’t shade each other.
After grafting, keep the temperature at 25-30℃ and the relative humidity of the air at above 80%; it will heal and take root in 20-25 days. 2. Most of the seedlings used for grafting cut roses are bud-grafted seedlings. The rootstocks used are the most common and most stress-resistant wild species of the genus, such as wild rose, pink rose and thornless dog rose. The latter is resistant to powdery mildew and has no thorns, making it an ideal rootstock.
Grafting by T-budding is the simplest. (1) Preparation of rootstock. In late autumn and early winter (i.e. mid-November to early December), cut a large number of rootstock cuttings, 20-21 cm long, remove the lower buds with a sharp knife, and only keep the top three buds. According to the diameter of the rootstock, grade them appropriately and soak the rootstock in 500-1000 times streptomycin solution for 10 minutes to prevent the occurrence of bacterial root cancer.
Then treat with 400 mg/kg naphthaleneacetic acid, and then insert the rootstock cuttings into a sunny bed in the open field, sheltered from the wind, with a spacing of 5 cm * 15 cm. The rootstock cuttings can also be buried in sand in the winter (bury the cuttings in a 50 cm deep pit in the shade in wet sand. In winter, prevent the sand from drying out too much and causing the cuttings to dry out). When the soil thaws in spring, take out the cuttings. If some callus tissue has formed at the base of the cut, it should be cut in time.
The management after cutting is the same as cutting propagation, but the wild rootstock takes root faster and has a higher rooting rate. It can be used as a rootstock after about one and a half months. The standard rootstock should be a two-year-old seedling with a diameter of 8 to 13 mm, healthy and free of diseases and insect pests. (2) Specifications of the rootstock. According to general regulations, the diameter of the rootstock for T-bud grafting is 0.5 to 2.5 cm; the bark is quite thin, the growth is active, and the epidermis is easy to separate from the wood.
The grafted bud should be grafted on the smooth epidermis of the rootstock 4 to 5 cm above the ground. When grafting rootstocks planted in rows, it is best to have all the grafted buds on the same side for easy management and inspection. If the rootstock is a potted seedling, this restriction does not apply. (3) Bud grafting time. It can be carried out during the growing season, usually in mid-March, early to mid-July to mid-September. Select branches that have sprouted in the same year as the scion, and the axillary buds on the scion should be well developed and full.
The rootstock bark is easy to peel, the operation is convenient, the efficiency is high, and after grafting, the healing is fast and the survival rate is high. (4) Bud grafting operation procedure (Figure 2-3). T-bud grafting step 1. Rootstock Preparation: ① Make a vertical incision approximately 2.5 cm long on the rootstock. ② Make a horizontal incision above the vertical incision. Twist the knife to pry apart the two skin layers. 2. Bud Preparation: ① Start cutting about 1.3 cm below the bud and work your way upwards until you reach 2.5 cm above the bud. ② Make a horizontal incision approximately 2 cm above the bud, penetrating the cortex into the xylem to remove the bud. 3. Grafting: ① Insert the bud into the two pried-apart skin layers. ② Make sure the horizontal incisions on the bud and the rootstock are aligned. ③ Secure the bud joint with wrapping. ① Make a vertical incision on the rootstock first, then a horizontal incision to form a T-shape. After making the horizontal incision, use a knife to pry apart the skin layers to facilitate insertion of the bud. Be careful not to make the incision too long.
② After preparing the rootstock and inserting the bud, remove the shield-shaped bud from the scion. The specific method is to start cutting from approximately 1.3 cm below the bud on the scion and work your way up to approximately 2.5 cm above the bud. The shield-shaped bud piece should be as thin as possible, but thick enough to maintain a certain degree of rigidity. A second horizontal incision should be made 1.3 to 2 cm above the bud to remove the bud piece.
③ Insert the shield-shaped bud piece with the bud between the two pried-apart pieces of epidermis, aligning the top of the bud piece with the horizontal incision on the rootstock. The bud piece should be firmly attached to the rootstock and covered with the two pried-apart pieces of epidermis, but leaving the bud exposed. ④ Bind with film or rubber bands, keeping the graft tightly attached to the rootstock until fully healed. Do not cover the bud when binding; tuck the end of the band under the adjacent loop.
The tightness of the binding is crucial: too loose a band will not secure the graft; too tight a band will cause the tape to become too thin and deteriorate quickly, leading to premature damage before the graft heals. Generally, the buds are tied from top to bottom to prevent them from being squeezed out of the horizontal incision. ⑤ After bud grafting, after one week in summer, if the petiole on the scion falls off immediately when touched by hand, and the skin color of the bud grafted in the T-shaped mouth is normal, it means that the graft has survived; otherwise, it means that the graft has not survived.
If there is enough time, you can graft again on the other side of the rootstock. The temperature is low in spring and autumn, the healing speed is slow, and the survival time is longer. Using a bud to propagate a plant is a rapid propagation method in conventional propagation. It can well maintain the characteristics of the variety and has a strong root system, which will lay a good seedling foundation for rose cut flower production. (5) Precautions for grafting propagation.
First, the grafting knife must be sharp and disinfected to prevent infection at the interface. Second, the grafting bud should be of appropriate length and thickness, with the rootstock and bud fitting snugly together. The binding should be secure and airtight. Third, the nursery should be watered before and after grafting to keep it moist, but the water should not soak the grafting bud. Fourth, the grafting process should be quick and accurate. Fifth, after the grafting takes place, any new buds on the rootstock should be promptly removed. When the grafting bud grows to over 15 cm, the rootstock strip should be cut off. Sixth, the nursery where the seedlings are grafted should be regularly loosened, weeded, and pest and disease controlled.
1. Cutting Method. Softwood cuttings should be taken in late spring or early autumn. Using a sprayer will enhance survival. This method can be used year-round, but rooting is most effective when the soil temperature is 20.5°C, the air temperature is 10°C, and the relative humidity is 70%-80%.
2. Grafting Method. The rootstock is usually wild rose seedlings. The optimal grafting period is January to February, and the main grafting methods are bud grafting and branch grafting.
3. Tissue culture. Select nodes 3 to 7 of recently flowered, semi-lignified branches. Remove the leaves, disinfect, and cut into single-bud segments for culture.
What are the techniques for growing cut roses?
Netting: When the plant reaches a certain height, flowering branches tend to fall over or bend. Some varieties have wide branch angles. Therefore, netting should be placed vertically on both sides of the bed. The width of the net should be determined by the bed surface. Generally, the net should be 18.5 x 18.5 cm, with poles at both ends, 1.8 to 2.3 meters high. Use nylon rope to connect the meshes on both sides. Pull the ends tight to open the net, allowing it to be moved up and down. Ground cover: Covering the ground with straw, wheat straw, sawdust, cottonseed hulls, etc. can inhibit soil moisture evaporation, reduce irrigation frequency, mitigate surface erosion, replenish CO2, and buffer temperature and humidity. Drip irrigation is preferred for watering. If watering with a hose, keep the nozzle close to the ground and spray at medium pressure, avoiding wetting the leaves. Fertilization: Cut roses require a large amount of fertilizer, primarily organic fertilizer (basal fertilizer). Chemical fertilizers are also needed to supplement the mineral elements in organic fertilizers, especially potassium. This is generally supplemented with each watering, such as KH2PO4. Liquid fertilizers can also be mixed and applied as a topdressing. Typical concentrations are 1%-2% for root application and 0.1%-0.2% for foliar spraying. During the growing season, increase the application of phosphorus and potassium fertilizers and reduce the application of nitrogen fertilizers.