Cultivation and Management Methods and Technical Key Points for Cut-Flower Roses
Roses, with their brilliant colors and delicate fragrance, have always been cherished by people. Cultivating fresh cut-flower roses in solar greenhouses allows year-round supply to the market and is truly another new path for farming families to prosper.
1. Graft propagation. Use wild roses (Rosa multiflora) or dedicated rootstock varieties as rootstock, and adopt the branch grafting method or the bud grafting method for grafting. Sow the rootstock in early April and transplant in April of the following year. The seedbed should be fertile, loose sandy soil, with a plant-to-row spacing of 20 cm x 80 cm. Perform bud grafting in June, and lift the seedlings for field planting in the spring of the third year.
2. Soil preparation. Choose fertile, loose sandy loam rich in organic matter and well drained, use fully decomposed livestock manure as base fertilizer at 45,000 kg to 60,000 kg per hectare, then disinfect the soil. The methods are: methyl bromide, 10 kg per 100 sq m, after treatment cover the soil with plastic film for more than a week; chloropicrin, 7.5 liters per 100 sq m, after treatment cover with plastic film for more than two weeks; DD mixture, 2.8 liters per 100 sq m, after treatment cover with film for more than two weeks.
3. Scientific planting. Use the raised-bed planting method. The bed is 1 m wide and 10 cm to 15 cm high, with two rows planted per bed, a large row spacing of 90 cm to 100 cm, a small row spacing of 30 cm, and a plant spacing of 20 cm, giving a density of 6 to 8 plants per sq m, with a walkway between beds 20 cm to 30 cm wide.
4. Adjusting temperature and humidity. For solar greenhouse cultivation, the daytime temperature should preferably be 20°C to 25°C, with a maximum not exceeding 28°C; the nighttime temperature should be kept at 12°C to 15°C; relative humidity should be 65% to 75%; pay attention to ventilation.
5. Rational fertilization. Roses like fertilizer; you can apply fertilizer to the roots or spray foliar fertilizers such as monopotassium phosphate, urea, Gaomeishi, and ferrous sulfate on the leaves. Apply little but often. Generally, apply liquid fertilizer once every 10 days, and apply compound fertilizer in winter.
6. Water management. Water when dry and drain when wet. After the seedlings are planted in spring, water thoroughly, loosen the soil after watering, and thereafter water as needed according to conditions. In summer, when soil temperature is high, watering should be done after 5 p.m. Roses tolerate drought but fear waterlogging; when rainfall is heavy, pay attention to drainage, and frequently weed and loosen the soil.
7. Pruning and pinching. 1. Pruning. Roses should be pruned before planting, and after planting the flower buds should be removed promptly. Begin harvesting flowers after 3 to 5 strong branches have grown. Thereafter, prune 3 to 5 times each year, and tidy the branch shape at any time, leaving 2 to 4 buds on each branch when cutting. When cutting, leave 1 cm above the bud, and cut obliquely downward toward the other side of the branch. The cut should be smooth. There are two types of pruning: first, low pruning, that is, leaving only two buds from the base of the branch upward and cutting off the upper part of the branch; this pruning method produces long and thick branches, large flower buds, and good quality. Second, high pruning, in which more buds are left on the lower part of the branch, more new branches are produced, and more flowers bloom, but the branches are short, the flower buds are small, and the quality is poor. Alternating these two pruning methods in production can control plant height and keep the roses at a longer growth cycle and higher productive capacity. Grafted seedlings are renewed about once every 8 years. 2. Pinching. When a new shoot grows to 15 cm to 20 cm, remove about 3 cm from the top, thereby promoting side buds to grow into side branches; when they reach a certain length, pinch again about 2 times, until the number of main branches and side branches of the whole plant is sufficient to produce a large number of flowers. Pinching in the early stage is to adjust plant shape, and after flowering it is to control the flowering period. When the flower bud reaches 10 mm to 13 mm in diameter, pinch off the branch tip down to the second leaf, which can advance the flowering period by about 7 days.
8. Pest and disease control. Ventilation reduces the incidence of disease; eliminate and burn virus-infected branches; through 4 weeks of high temperature, viruses in the plant can be eliminated or reduced. Common rose diseases are black spot, powdery mildew, rust, and so on, which can be controlled with 80% mancozeb wettable powder or 50% benomyl wettable powder at 800 to 1,200 times dilution. To control pests such as aphids, thrips, leaf rollers, and scarab beetles, use 50% fenitrothion at 1,000 times dilution.
9. Harvesting and grading. Roses should be cut when temperature is low and humidity is high. Generally, flower harvesting begins about 10 months after planting, harvesting when the flower buds are slightly open (about 2 days before blooming). The cut branches should have 5 internodes or a somewhat longer length. After cutting, immediately place them in water, transport them back to the workroom for grading, and tie every 10 branches into 1 bundle. Grading standards: grade one product has a branch length of 55 cm to 60 cm and uniform flowers; grade two product 45 cm to 54 cm; grade three product 35 cm to 44 cm; below grade 35 cm or less. After packaging with cellophane, trim the branches evenly and place them in water.
10. Preservation and storage. Cut roses have a short vase life and do not tolerate long-distance transport. Treating with 8-hydroxyquinoline sulfate and storing in a cold room at 3°C to 4°C can keep them fresh for 3 days. If cut roses are not to be marketed @#@136@#@ and need long-term storage, they can be placed in a sealed cold room with 1% oxygen, 5% carbon dioxide, and a temperature of 0°C to 1°C, where they can be kept fresh for 20 days to 30 days.