Current market price of watermelon per jin and the harvest time and methods for winter-spring crop cultivation
Watermelon, also known as summer melon, cold melon, and Qingmen Lvyu Fang, is a common annual fruit in our country. Because of its juicy and sweet flesh and its ability to aid digestion, promote urination, and reduce fever, it is deeply loved by people. So what is the current market price of watermelon per jin? When is the winter-spring crop planted? When is it harvested? How is it grown?
Latest market price:
Planting time:
Raise seedlings in early to mid-January, transplant in February, and begin marketing in mid-to-late April to early May.
Harvest time:
Early-maturing varieties reach maturity 28 d after flowering, while mid-maturing varieties need 28-32 d. To judge whether a watermelon is ripe, make a comprehensive analysis based on the color of the rind, glossiness, wax bloom, shape of the fruit stalk, degree of pubescence shedding, the dried node position of the tendril, and the sound and vibration when patted or tapped. Generally, a mature fruit has clear rind stripes and a glossy surface, the navel and fruit stalk shrink, the fruit stalk pubescence falls off, and when patted by hand or flicked with a finger, it gives a low, dull thudding sound. During harvest, it must be handled gently.
Cultivation techniques:
1. Variety selection
Watermelon varieties for early-maturing greenhouse cultivation should have: female flowers at low node positions and a high female flower rate, with about 30 d from female flower opening to fruit maturity; relatively strong tolerance to low temperature and weak light; steady growth and strong fruit-setting ability on the main vine; and no strict requirements for harvest maturity. Therefore, choose early-to-mid-maturing varieties with good early maturity, excellent quality, good yield potential, strong stress resistance, and no strict requirements for the fruit's mature harvest period.
2. Land preparation and fertilization
Apply 5000 kg of high-quality farmyard manure, 200 kg of cake fertilizer, 30 kg of potassium sulfate, 100 kg of superphosphate, and 50 kg of ammonium bicarbonate per 667 sq m. Fertilizer should be applied to the soil in 2 applications, namely a broadcast application over the ground and a concentrated application in furrows under the cultivation ridges, and thoroughly mixed with the soil. Use the method of planting in wide and narrow rows with double rows and vines climbing toward each other. The narrow row spacing is 60 cm, and the wide row spacing is 180 cm. Open north-south furrows on the melon rows according to the row spacing, apply fertilizer and irrigate in the furrows, then draw soil back to form cultivation ridges and vine-climbing beds about 15-20 cm high. Cover the two cultivation ridges with plastic film.
3. Timely transplanting
Transplant when the soil temperature under the film in the shed is stably above 15°C. In terms of seedling age, transplant when the watermelon has three or four true leaves, 25-30 d after grafting. Transplanting should be done on a sunny morning and completed before 14:00, preferably with 3-5 sunny days after transplanting. Planting density must not be too dense; generally plant about 800 plants per 667 sq m. After transplanting, build small arched tunnels on the cultivation ridges to help increase temperature and preserve moisture.
4. Management after transplanting
(1) Temperature management
The 7 d after transplanting is the key period for seedling recovery. Generally, keep the greenhouse closed without ventilation, at 25-30°C or slightly higher during the day on sunny days and 18-20°C at night. Pay attention to insulation at night and on cloudy days. Keep the soil temperature in the small arched tunnels in the greenhouse above 15°C and the air temperature above 10°C. When the air temperature in the small arched tunnels exceeds 30°C, ventilate from both ends to prevent high-temperature damage to the seedlings.
(2) Fertilizer and water management
Fertilization and irrigation must be carried out reasonably according to soil moisture and plant growth. Generally, apply a heavy topdressing after fruit setting, that is, when the watermelon is the size of an egg, the surface pubescence gradually falls off, and the melon surface shows obvious gloss, flush chemical fertilizer with water, using 20-30 kg of compound fertilizer per 667 sq m. Water demand increases during the fruit enlargement period, and generally watering is needed two or three times. At this time, watering should be done simultaneously in the planting beds and the vine-climbing beds. Stop watering in the late fruiting stage to avoid affecting watermelon quality. In the later stage, foliar topdressing is mostly used, spraying the leaves with a mixture of 0.3% urea plus 0.2% potassium dihydrogen phosphate, and pesticides for disease and pest control can also be added at the same time.
(3) Pruning and vine pressing, retaining fruit first
25-30 d after transplanting, when the vines are 30-35 cm long, in addition to retaining the main vine, select and retain 1 robust side branch at the base of the main vine, and remove all other secondary and tertiary vines, always maintaining 2 vines, one main and one side vine. This method has more fruit-setting opportunities, less likelihood of empty plants, and a larger leaf area, which helps increase single fruit weight.
(4) Artificial pollination
Watermelon cultivation in solar greenhouses must be artificially pollinated. Artificial pollination not only increases the fruit-setting rate by 32%-40% compared with natural pollination, but also purposefully adjusts the fruit-setting position, coordinates the balanced growth among fruits, and gives each fruit sufficient nutritional area to ensure large fruit and high quality. Watermelon flowers open from 05:00-09:00, and pollen is most abundant and has the strongest vitality from 06:00-09:00. Under general weather conditions, artificial pollination should be completed before 09:00, and under special weather conditions it should also be completed before 10:00. The method is to take an open male flower, turn back the petals, expose the stamens, and smear the stigma of the female flower. Smearing should be gentle, and the pollen should be distributed evenly. One male flower can pollinate 3-5 female flowers.
5. Control of watermelon diseases and pests
(1) Anthracnose
Watermelon anthracnose is a fungal disease. It is more severe in low-lying areas with poor drainage, or where there is excessive nitrogen fertilizer, poor ventilation, and continuous cropping. Watermelons from severely affected fields or harvested after rain can also develop the disease during storage and transport. In the early stage of the disease, spray 70% thiophanate-methyl plus 75% chlorothalonil wettable powder at 800 times dilution, or 25% pyraclostrobin emulsifiable concentrate at 2000-3000 times dilution, once every 7-10 d, for two or three consecutive treatments.
(2) Damping-off
This disease mainly occurs when seedlings have one or two true leaves, and there is less incidence after 3 true leaves. Seeds can be treated with 72.2% propamocarb hydrochloride aqueous solution at 500 times dilution, or seed-dressed with 50% thiram wettable powder at 0.2%-0.3% of seed mass. For field control, spray 68.75% propamocarb hydrochloride · fluopicolide suspension concentrate at 800-1200 times dilution, or 69% dimethomorph • mancozeb wettable powder at 1000-1500 times dilution, once every 5-7 d depending on disease severity.
(3) Fusarium wilt
Watermelon fusarium wilt, also called wilt disease, occurs relatively severely in the old watermelon-growing areas of Henan Province. In the early stage of the disease, leaves gradually wilt from the back toward the front, resembling water shortage, and it is most obvious at noon. First, select disease-resistant varieties, practice rotation with other crops, control nitrogen fertilizer application, and increase phosphorus and potassium fertilizers and trace elements. Before transplanting and seedling recovery, or in the early stage of disease on scattered diseased plants, drench the roots with 5% junduqing aqueous solution at 800 times dilution, or 50% compound thiophanate wettable powder at 500 times dilution, or 50% carbendazim wettable powder at 500 times dilution, using 0.25 kg of solution per plant, for two or three consecutive treatments depending on disease severity.
(4) Melon aphid
Melon aphid, namely cotton aphid, commonly known as honey insect. Adult aphids or nymphs gather on the undersides of leaves and tender tips to suck sap and secrete honeydew. After melon seedlings and growing points are damaged, leaves curl, growth stagnates, and they may even wilt and die. When leaves of adult plants are damaged, they may wither and fall early, shortening the fruiting period and causing yield reduction. Melon aphids develop quickly and reproduce strongly. They can develop and reproduce at 10-30°C, with the optimum temperature being 16-22°C. Under suitable temperature and humidity conditions, one generation can be completed every 5-6 d. For chemical control, use 5% imidacloprid emulsifiable concentrate, 3% acetamiprid emulsifiable concentrate, or 2.5% cyhalothrin emulsifiable concentrate, or 50% fenpropathrin emulsifiable concentrate at 2000-4000 times dilution. These insecticides cannot be used singly for a long time, as resistance is easily produced, so rotating several pesticides is recommended.