Detailed Explanation of Key Points for Early Spring Greenhouse Cultivation Techniques of Winter Melon

Winter melon (scientific name: Benincasa hispida (Thunb.) Cogn.) is an annual herbaceous plant with tendrils on the stem that can climb and vine, large leaves, and yellow flowers. The fruit is spherical or elongated cylindrical, with hairs and white powder on the surface, and dark green or light green skin. It is a relatively common vegetable.

Growth Habits of Winter Melon

The stem of winter melon has fine hairs; the leaves are slightly round and palmately lobed with hairs on the surface; yellow flowers; round, flat-round or oblong fruit, with size varying by variety, ranging from several jin to several tens of jin; the skin of winter melon is green, and the mature fruit of most varieties has white powder, thick and loose juicy white flesh, with a mild taste; white flat seeds, some with narrow wing-like edges.

When young, the melon is green and hairy; after ripening, it turns bluish, with a hard thick skin covered in powder, and fat white flesh. The melon pulp is called "gualian", which is white and spongy like cotton and can be used for washing clothes. The seeds in the pulp are called "guaxi" and grow in rows. It ripens in the winter months, hence the name winter melon. After frost, the winter melon is harvested; the flesh can be steamed and eaten, or preserved as candied fruit with honey; the seed kernels are also edible. It can serve as both a vegetable and a fruit. Any harvested melons should avoid contact with alcohol, lacquer, musk and glutinous rice, otherwise they will certainly rot.

Early Spring Greenhouse Cultivation Techniques of Winter Melon

I. Seedling Raising: For early spring winter melon production, short-vine early-maturing varieties should be selected, and seedlings should be raised in mid-to-late December. During seedling raising, the temperature should be 25-28°C during the day and 13-15°C at night. If this temperature cannot be reached, heating wires or a water stove can be used for heating. To ensure whole-root transplanting, seedling raising in 9 cm × 9 cm nutrient soil blocks is required. Transplanting should be done when the seedlings reach 50 days of age, with 5 leaves, a stem diameter of more than 5 mm, and a plant height of 18 cm.

II. Transplanting: The transplanting time is mid-to-late February. Before transplanting, the soil should first be prepared. Open furrows at a uniform row spacing of 70 cm, choose clear and fine weather, place the seedlings along the furrow, then water. After the water is absorbed, close the soil into single ridges with a ridge height of 15 cm and width of 25 cm. The suitable transplanting density is about 2,500 plants per mu.

III. Management After Transplanting: Winter melon in solar greenhouses must be cultivated on trellises. When building the trellis, one trellis per row is required, using bamboo poles or wooden sticks to build a "door"-shaped flat trellis with a height of about 80 cm, and the top of the trellis should be firmly tied with wooden poles or small bamboo poles. Timely remove side branches other than the main vine, leaving 1 main vine. When guiding the vines onto the trellis, let the melon vines cross on the ground before going onto the trellis; that is, when one row of melon vines climbs on the ground to the second row, guide the vines onto the trellis, and when the second row climbs on the ground to the first row, guide them onto the trellis. In this way, the fruit-setting position is exactly on the opposite cultivation ridge, which is relatively neat and convenient for management. Prune regularly to prevent multiple heads and tangled vines, and maintain the dominance of the main vine. Before fruit setting, temperature management should be proper, with 28-30°C during the day and 13-15°C at night.

For early spring production of winter melon in solar greenhouses, generally the second female flower bud is retained, at the 10th-12th leaf. During normal growth, the female flower opening position is exactly on the cultivation ridge. After flowering, both hormone treatment and artificial supplementary pollination measures must be adopted to ensure stable fruit setting, and after fruit setting, rapid growth and early marketing. In greenhouses, air humidity is high and temperature is high; after flowers open, anther dehiscence and pollen shedding are slow. Therefore, after the female flower of the second fruit bud opens, use 100 ppm of 2,4-D to smear the melon stalk of the flower from 8-9 a.m.; after 10 a.m., the anthers crack and begin to shed pollen; around 11 a.m., carry out artificial pollination in time. Only 1 fruit should be pollinated per plant, and the rest should be removed in time. After fruit setting, a temperature of 30-32°C during the day and 15-18°C at night is relatively suitable.

After winter melon sets fruit, if water and fertilizer are timely, it can be marketed in 25-28 days. When the young melon is about 50 g (such as the size of an egg), it is necessary to water and topdress in time. When watering, apply 25 kg of urea per mu, and after 8-10 days, choose clear and fine weather to water and topdress again. When watering, prevent flooding irrigation, so as not to submerge the young melon and cause fruit abortion. After watering, increase ventilation to prevent excessive air humidity and disease. During the melon swelling stage, the temperature requirement is 30-35°C during the day and 15-18°C at night. To reduce nutrient consumption, remove the lower old leaves in time.

When the first melon is harvested in late April, strengthen water management again, which can promote continuous fruit setting.

Cracked winter melons will seriously affect appearance and quality. In addition, cracked melons also allow pathogens to invade the melon and reproduce, causing partial deterioration or rot of the winter melon, which is very unfavorable for storage and sales and brings economic losses to vegetable growers. The following are several effective measures to prevent winter melon cracking:

(1) Select crack-resistant varieties;

(2) In rainy areas or rainy seasons, adopt cultivation methods with deep furrows, high beds, or ridging and trellising;

(3) Increase application of organic fertilizer, increase soil permeability and water retention, make soil water supply uniform, promote robust plant growth, and prune in time so that the fruit develops normally;

(4) The fruit tip and the peel touching the ground are thick, with fewer wall cell layers. During cultivation, they can be turned over to promote fruit development and prevent cracking. When necessary, spray 0.1% zinc sulfate or copper sulfate solution during the fruit expansion period to improve heat resistance and crack resistance.

(5) Spray gibberellin solution after petals fall off, once every 7 days for 2-3 consecutive sprays, which can also prevent fruit cracking.