1, Temperature: Watermelon is a thermophilic crop, extremely cold-resistant, and will die in case of frost. The suitable germination temperature of seeds is 28℃-32℃. If it is lower than 20℃ or higher than 40℃, it is difficult to germinate. The suitable growth temperature of watermelon is 18℃-32℃. The growth temperature of root hair is 65438 04℃, and the suitable temperature for root growth is 25℃-28℃. The suitable temperature for seedling stage is 22℃~25℃, and that for jointing stage is 25℃ ~ 28℃. The suitable temperature for fruit expansion and ripening is 28℃-32℃. When the temperature is insufficient, the fruit expands slowly, the fruit is not big, the peel becomes thicker, the meat is thick and hard, the sugar content decreases, and the quality and yield are not ideal.

2. Humidity: Watermelon is a drought-tolerant crop, but it needs a lot of water during the whole growth period. Especially in the heading, vine extension and expansion stages, it is especially necessary to meet its demand for water in order to obtain high quality and high yield. Watermelon likes dry climate, and rainy climate is easy to get sick. However, excessive water shortage will affect the normal growth and development of plants, or it is difficult to bear melons, or the fruits are small, which is not conducive to the formation of high quality and the improvement of yield. Watermelon is extremely intolerant to waterlogging. If there is water in Gua Tian, the roots will suffocate and plants will die due to lack of oxygen in the soil. Rainy watermelon growth period will lead to vine overgrowth, difficulty in pollination, difficulty in fruiting, and decline in yield and quality.

3. Illumination: Adequate illumination is the most important condition for watermelon cultivation. During the whole growth period of watermelon, there must be at least 600 hours of light time to meet the needs of growth, flowering and fruiting. The normal growth of watermelon needs more than 5 hours of light every day on average. Insufficient light, low temperature, increased humidity, excessive growth of stems and leaves, serious diseases, few female flowers, and difficult to bear fruit. Especially in the flowering and fruiting period, if it rains for a long time, although the plants develop well, it is difficult for political parties to bear fruit. Even if the weather improves in the future, it will fail to bear fruit because the stems and leaves are too lush or the diseases are serious, which will lead to the failure of cultivation.

4. Soil: Watermelon is a deep-rooted crop, because its root system is delicate, drought-resistant and moisture-proof. Therefore, sandy soil with good drainage, deep soil layer and fertile soil should be selected.

Cultivation. Watermelon is suitable for growing in nearly neutral soil. Watermelon can grow normally in the soil with total salt content below 0.2% in the range of PH 5~8.

Fusarium wilt is easy to occur, so it is necessary to apply alkaline fertilizers such as lime and plant ash to neutralize and improve the soil, and good results can be obtained.

5. Rotation: Watermelon should not be continuously cropped, and the continuous cropping plots often fail due to illness. In particular, watermelon Fusarium wilt is a serious disease during continuous cropping, which requires crop rotation. Self-rooted seedlings in the same plot should be rotated at least once every five years. Wheat, corn, sorghum, rice and sugarcane are the best crops for watermelon, so avoid stubble.

Second, the cultivation techniques

1. Timely sowing: Nursery in protected land, sowing in the middle and late March in northern Zhejiang.

Sow in early and middle March. The seedlings are about 30 days old and transplanted in the open field. The live broadcast of open space will be carried out around April 10.

2. Seed treatment: soak the seeds with 55℃ hot water and warm water before sowing, and naturally cool them to kill the pathogenic bacteria on the surface of the seeds. Or use 50%

500 times of solution, in which watermelon seeds are soaked 1 hour, can also achieve the purpose of disinfection and sterilization.

3. Accelerating germination: Soak the seeds 2 days before sowing to accelerate germination, soak the sterilized seeds in clean water for 4 hours at room temperature, then wrap the seeds with gauze and rub them in warm water until the water is clear. Wipe off the water and mucus on the seeds and dry them indoors in a warm and sunny place for half an hour. After the seeds are dried, spread them on 2-3 layers of dense wet cloth. Seed sowing thickness should be less than 3cm, covered with 2-3 layers of wet cloth, placed in enamel pots or other containers, and then placed in incubators or other heat sources. The temperature in the seed pile is kept at about 30℃, and it is turned once after 20 hours to make the seeds evenly heated. When applying dry cloth, wash it thoroughly with warm water and wring it out. Under the above conditions, the seeds can germinate after 36 hours.

4. Sowing: The seeds that accelerate germination should be planted in the sowing hole or nutrition bowl when the buds grow to 0.5cm, and the soles of feet should be watered before sowing. Seeds should be laid flat on the soil surface. If the bud is curved, the bud end should be downward, and the seed should be covered with 2 cm of soil. After the plastic film is covered, a small greenhouse is formed in the sowing hole. As soon as the seeds touch the soil, a small hole is dug in the top film outside the greenhouse. With the increase of the outside temperature, the hole gradually becomes larger until the melon seedlings are led out of the film and sealed with soil pressure film. Don't lean the film on the stem to avoid high temperature burns, causing disease or seedling death.

5. Seedling raising: Seedling raising in a nutrient bowl in a greenhouse or a small arch shed is convenient for seedling management, sowing time is advanced, and it is easy to ensure the whole seedling after planting. Nutritional products can be made of plastic bowls or paper or plastic films. Bowl height 10cm, upper caliber 8- 10cm.

( 1)

Preparatory work:

It should be nutritious and permeable. Generally use one third.

Manure, one third of plant ash. Due to the difference of soil and fertilizer texture, the proportion of its components can be changed appropriately. It is advisable to water until the wet and dry conditions are moderate, and the hands are clenched into balls, which are loose but not hard. Per cubic meter

Phosphate fertilizer or three noes should also be added

2kg, mix well.

(2) Bagging and sowing: put the prepared nutrient soil into a nutrient bowl, gently compact the nutrient soil in the bag, and place it neatly and tightly on the seedbed. Water is poured on the seedbed, and the seeds with accelerated germination are placed in the center of the nutrient bowl, one in each bowl, and covered with 1.5-2cm of moist nutrient soil.

(3) Seedling management: Before the seedlings are unearthed, heat preservation and moisture preservation are the main methods. The temperature of seedbed should be kept between 25-30℃ to promote the rapid emergence of seedlings. It is easy for seedlings to grow in vain from behind the soil until the first real leaf appears. Timely and proper ventilation is the main measure to prevent them from growing in vain. During this period, the temperature in the bed should be reduced to 22℃-25℃ during the day and 65438 05℃-65438 08℃ at night. After the first true leaf appears, we can know that when the temperature rises, it is 25℃-28℃ during the day and 18℃- 10℃ at night. About 7 days before sowing, stop watering the seedbed and gradually exercise the seedlings according to the weather conditions. When raising seedlings, in the temperature range, the illumination time of seedbed should be extended as much as possible to make the growth bond of seedlings strong.

6. Land preparation: Southeast

The area is large, and the watermelon should be ridged to prevent water accumulation in the field. Generally, the row spacing is 2.5m-3m, which should be combined with soil preparation.

Fertilizers are applied in layers, and all 667m2 are applied.

high quality

About 1500kg, according to

, applying three elements.

15-50kg, phosphate fertilizer 50kg, potassium sulfate10-20kg.

7. Planting: When the daily average temperature outside is stable above 14℃ and the watermelon seedlings have three leaves and one heart, it is the suitable planting period for watermelon. Different planting densities

, different varieties, generally 400~450 large fruit varieties /667㎡, 500 medium fruit varieties /667㎡. Before planting, punch holes on the ridge surface covered with plastic film according to the plant spacing. The aperture should be the same as the diameter of the nutrition bowl, with a general aperture of 10cm and a depth of 10cm. Before transplanting, completely empty the nutrition bowl, take out the nutrition bowl, and transplant the seedlings with soil into the planting hole. The planting depth is about 1cm higher than the boundary surface, and slightly higher than the boundary surface after sinking. Plant straight and upright, cover with soil around, and gently press. If the soil is dry when transplanting, water it.

8. Pruning: Watermelon pruning forms include one vine, two vines, three vines and many vines.