Detailed Explanation of Key Management Techniques for Forcing Cultivation of Tulips

Tulip (Tulipa gesneriana), of the Liliaceae family and the genus Tulipa, is a perennial bulbous herbaceous flower, and is a world-famous material for cut flowers as well as flower beds and flower borders. Its elegant and graceful flower form and pure, simple fragrance make it deeply loved by people. Due to the tulip's own biological characteristics and ecological habits, under natural cultivation conditions in northwest China, people can only catch a glimpse of its elegance and splendor from May to June each year. In recent years, in order to enable tulips to appear on the flower market stage from New Year's Day to the Spring Festival, we adopted forcing cultivation methods in a solar energy-saving greenhouse, and summarized some successful experiences for reference by peers and flower enthusiasts.

1 Variety Selection

Two varieties that perform relatively well in northwest China were selected: Czoolden Apldoom and Oxford.

2 Test Site

Solar energy-saving greenhouse at the test site of the Horticulture Institute, Qinghai Academy of Agriculture and Forestry Sciences.

3 Cultivation Technical Regulations

3.1 Pre-sowing Preparation

3.1.1 Soil treatment: Between September 20 and 25, apply sufficient base fertilizer in the greenhouse: decomposed chicken manure 11250 kg/hm2, diammonium phosphate 375 kg/hm2, compound fertilizer 450 kg/hm2; and apply 25% carbendazim wettable powder 15 kg/hm2; ferrous sulfate 225 kg/hm2 and 3% carbofuran 75 kg/hm2 to disinfect the soil. After application, deep plough 20-25 cm and cover with plastic film.

3.1.2 Temperature control: After September 25, raise the temperature above 30°C to facilitate soil fertilization and sterilization and insect killing. By October 8, remove the greenhouse film and plastic film, and restore to the external ambient temperature.

3.1.3 Bulb treatment: After peeling, soak in 1000 times diluted 25% carbendazim wettable powder solution for 40-60 min, then air-dry for later use.

3.2 Sowing

3.2.1 Sowing time: October 15-20.

3.2.2 Sowing method: open furrows and sow in holes, furrow depth about 12 cm, plant spacing 15 cm × 20 cm, soil covering thickness 2 times the height of the bulb.

3.3 Field Management

3.3.1 After sowing, water thoroughly to settle the plants; under natural conditions the root system grows fully and the buds begin to sprout. By November the ground surface begins to freeze. Bulb growth stops. In late November, install the greenhouse film, raise the temperature to between 15-22°C, water thoroughly once, and the aboveground part begins to grow. Thereafter water once a week; after budding, appropriately control moisture, with watering once every 10 d being suitable.

3.3.2 Temperature: Throughout the entire growth process, temperature control is key. First, the root system is fully developed at a suitable temperature, then the vernalization process is completed through low temperature, and then growth and development proceed at a suitable temperature; the temperature control throughout the growth period is shown in the figure.

3.3.3 Topdressing: After December 1, in conjunction with watering, apply nitrogen, phosphorus and potassium compound fertilizer 3-4 times, each time 75-1125 kg/hm2. After December 20, apply foliar fertilizer monopotassium phosphate 1500 times diluted solution 2-3 times to promote budding and flowering.

3.3.4 Tiller removal: During the growth period, some daughter bulbs produced will sprout and grow; in order to avoid nutrient loss, promptly remove the sprouting shoots.

3.3.5 Pest and disease control: During the forcing cultivation of tulips, they are susceptible to damage from dry rot (sclerotium rot), flower-breaking virus disease, bulb rot, bulb mites and so on. The control methods are respectively:

① Dry rot (sclerotium rot): promptly remove diseased plants when found, and spray the remaining plants with 500 times diluted 80% zineb wettable powder solution.

② Flower-breaking virus disease and bulb rot: promptly remove diseased plants when found, and spray 1000 times diluted 40% omethoate emulsifiable concentrate for control; to reduce the chance of aphid virus transmission, 800-900 times diluted 25% derris extract can also be sprayed for control.

③ Bulb mite: inject and spray 1000 times diluted 25% chlorfenethol on the bulb.

4 Discussion

This method is only a method for making tulips available on the market from New Year's Day to the Spring Festival, and is one of the methods in tulip forcing cultivation. The relevant details still need further discussion.