Detailed Explanation of Key Techniques for High-Yield Watermelon Cultivation

What is the most enjoyable thing about summer? Nothing beats "blasting the air conditioner under a quilt while watching movies and eating watermelon." Indeed, watermelon has almost become synonymous with summer; the mere thought of summer brings watermelons to mind. Watermelon quenches thirst and relieves heat, making it one of the fruits commonly kept at home during summer. For farmers, watermelon is also a good planting choice, so how can watermelons be grown for high yield? What are the key points of watermelon cultivation? The following is presented by Qinnong Net: the key technical points for high-yield watermelon cultivation.

The cultivation process of any agricultural product cannot do without the five basic steps of land selection -- seed selection -- sowing -- application of water and fertilizer -- harvest, and watermelon is no exception. What this article presents, however, focuses on the three key periods after adequate preparatory work such as land selection and seed selection has been done, specifically as follows:

I. Sow and germinate seeds at the right time, and carefully raise and transplant seedlings

1. Sowing period. For open-field sowing, mid-to-late April is suitable; if the supply period is to be delayed, sowing can be done in early June; if insulated seedling raising is used for early supply, sowing can be done in late March to early April.

2. Seed rate. Use 1-1.5 liang of seed per mu of field; hybrid watermelon seeds are larger, so use 2-2.5 liang per mu of field.

3. Seed soaking and germination. First soak the seeds in warm water at 50-55 degrees C (if no thermometer is available, use two parts boiling water plus one part cold water) for 15-20 minutes, then add a small amount of cold water to bring the water temperature down to about 30 degrees C. Wait for the water to cool naturally and soak for 2-3 hours. Then put the soaked seeds into a small cloth bag, rinse clean with clear water and air-dry, mix with an equal amount of clean wet river sand, wrap in cloth and spread flat to a thickness of about one finger for germination. The suitable temperature for watermelon seed germination is 30-35 degrees C; they can also be placed in a 30 degrees C constant-temperature chamber or beside a stove for germination. Generally after 48 hours all seeds can germinate.

4. Open-field sowing. When the sprouts grow to 1-2 fen, they can be selected for sowing, with 2-3 seeds per hill. When sowing, point the sprout tip downward and cover with soil about 2-3 cm thick. Immediately after sowing, water to settle the roots; if the weather is sunny, water once more on the 2nd-3rd day. When the seedlings have 2-3 true leaves, thin to a final stand, removing the weaker plant from hills that have two plants, and promptly fill in gaps where plants are missing.

5. Insulated seedling raising. For seedling raising in nutrient pots covered with plastic film, meticulous work is required, and the following key links should be handled well. (1) Making the nutrient pots. The pot bodies can be made from old newspapers or book paper into paper tubes 20 cm long, 13 cm wide, 8-10 cm high, and 6 cm in diameter. (2) Preparation of nutrient soil. Use 60-70% garden soil that has not grown cucurbits in recent years, add 10-15% sieved coal ash or burnt soil ash, add 20-25% decomposed pig and cattle manure and 0.2% phosphate fertilizer, and mix thoroughly. At least 300 jin or more should be prepared per mu. After mixing, pile it up, cover it tightly, and keep it for later use. (3) Management and transplanting of film-raised seedlings. Once true leaves appear, pay attention to ventilating the seedbed, letting in light, and adjusting temperature and humidity to prevent the occurrence and harm of damping-off, anthracnose, and Rhizoctonia solani. When the watermelon seedlings have two leaves, choose good weather to harden the seedlings and uncover the film. When the watermelon seedlings have two leaves and one heart or three leaves and one heart, and the outside temperature has stabilized at 15 degrees C, they can be transplanted to the field in a timely manner.

II. Reasonable close planting and good fertilizer management

1. The planting density of watermelon varies with variety and soil fertility, and about 450 plants per mu is suitable. For varieties with medium vigor, about 500 plants is suitable. That is, with a bed width including trenches of 9 chi, plant one row along each side of the bed, with a plant spacing (hill spacing) of 2.6 chi.

2. Cultivate and loosen the soil and remove weeds in a timely manner. Generally, cultivate 2-3 times. In topdressing, grasp the principle of small meals but frequent feeding, first light and then heavy.

3. Seedling-promoting fertilizer: Application can begin when the watermelon seedlings have settled in and show true leaves, applying once every 10-15 days, each time 15-20 dan per mu (each dan contains 10% decomposed human and livestock manure, plus 1 liang urea, and 100 jin water). On rainy days, 3-5 jin urea per mu can be applied in holes 2-3 cun from the roots.

4. Vine-spreading fertilizer: Apply when the watermelon seedlings have 5-6 leaves, using 100-200 jin decomposed cake fertilizer and 10-20 dan human and livestock manure per mu, applied in holes opened one chi from the base of the plant in the direction of vine extension.

5. Fruit-fattening fertilizer: When 60-70% of the watermelons are as large as eggs, apply 100-200 jin cake fertilizer and 15-20 dan human and livestock manure per mu in holes.

First-fruit fertilizer: When most watermelons are as large as a bowl, use 15-20 jin urea + 5-8 jin potassium fertilizer per mu, mixed with water and applied near the base of the watermelon plant.

6. Second-fruit fertilizer: After the first batch of watermelons is picked, in order to grow the second and third batches well and prevent premature decline of the vines, apply 20-26 jin urea per mu.

III. Take multiple measures to increase the fruit-setting rate

1. Pruning and removing suckers: Pruning methods include single-vine, two-vine, and three-vine types. The single-vine type keeps the main vine and cuts off the side branches on the main vine. This method results in fewer leaves per plant and smaller fruit shape, and is generally only suitable under high-density conditions. The two-vine or three-vine type removes the side branches sprouting from the leaf axils of nodes 3-7 at the base of the plant, keeping only 1-2 branches that grow vigorously and in suitable directions. Pruning work should be carried out in stages, mainly in the early stage of vegetative growth and the early fruiting stage. The first pruning should be done when the 2nd-3rd female flower on the main vine opens and several relatively vigorous side branches have formed around the node of the female flower; side branches should be cut off in time. When the fruit set on the main vine is as large as an egg, pruning should stop. Sucker removal should be carried out from fruit setting until before the whole field of watermelons is harvested, wiping out excess suckers, reducing tender leaves and small leaves, retaining large and strong leaves, concentrating nutrients, and promoting fruit development.

2. Vine pressing and vine arranging: Vine pressing method: When the watermelon vine grows more than 1 chi and begins to fall over, press a clod of soil in the direction opposite to the extension of the main vine so that the main vine leans forward. To prevent damage from wind and rain, press once every 4-5 nodes thereafter. Vine arranging method: When the main vine extends, straighten the vine and arrange it evenly; afterward, simply keep the growing point in the correct position. Generally, arranging 3-4 times and pressing 3-4 times is sufficient.

3. Manual assisted pollination. Method: In the early morning, pick male flower buds that will open that day and place them in a small basin to let them open naturally. After the female flower opens, peel off the petals of the male flower and smear the twisted anthers onto the honeycomb-like stigma of the female flower. Each male flower can pollinate 1-2 female flowers. However, care should be taken not to touch the ovary so as to avoid damaging it. Pollination is generally carried out before 9 a.m. When field plants grow uniformly, the nodes at which female flowers open are relatively neat, and generally one flush of flowers is 5-6 days apart. Therefore, manual pollination need not be carried out every day; it is enough to select the ideal fruit-setting position and carry it out for 2-3 days at full bloom.

4. Fruit selection and retention. Generally, it is suitable to retain the fruit set by the 2nd-3rd female flower on the main vine. Without pruning, several fruits may sometimes set on one plant, and the fruit shape will be significantly reduced. Poorly shaped young fruits can be removed, leaving 1-2, concentrating nutrients and increasing fruit size.

5. Use of hormones. Spraying flower-and-fruit-preserving king can significantly increase the fruit-setting rate, but it must not adhere to young fruits.

To achieve high yield in watermelon cultivation, one can never do without practice and the accumulation of experience. The above is a summary compiled by Qinnong Net, based on the experience of others, of the key technical points for high-yield watermelon. When applying them in practice, fruit growers can combine their own experience and the local climate and environment, adapt measures to local conditions, and develop their own high-yield techniques.