Watermelon seedlings that have just been transplanted into the greenhouse have high weather temperature, dry soil and less watering for the first time. Can you water them every day?

1. Environmental conditions suitable for watermelon growth. Temperature: Watermelon is a warm 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 temperature of root hair growth is 65438 04℃, and the suitable temperature of root system 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 skin is thick, the meat is rough 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 fruit-bearing stage, leaf-spreading stage and expanding stage, the demand for water must be met in order to obtain high quality and high yield. Watermelon likes dry climate, and rainy climate is easy to get sick. Too little water 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 resistant to waterlogging. If there is water in Gua Tian, the roots will suffocate and plants will die because of lack of oxygen in the soil. Rainy growing season of watermelon will lead to overgrowth of vines and leaves, difficulty in pollination and fruit setting, and decrease of 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, high humidity, overgrown stems and leaves, serious diseases and few female flowers all make it difficult to bear fruit. Especially in the flowering and fruiting period, if it rains for a long time, the plants will develop well, but it is also difficult to bear fruit. Even if the weather gets better in the future, the cultivation will not bear fruit because the stems and leaves are too lush or the diseases are serious. 4. Soil: Watermelon has slender roots and is resistant to dry and wet. It is a deep-rooted crop and should be planted in sandy loam with good drainage, deep soil layer and fertile soil. Watermelon is suitable for growing in nearly neutral soil. Watermelon can grow normally in soil with PH value of 5~8 and total salt content less than 0.2%. Fusarium wilt is easy to occur in acidic soil, so it is necessary to apply alkaline fertilizers such as lime and plant ash to neutralize and improve the soil, which can achieve good results. 5. Rotation: Watermelon is not suitable for continuous cropping. Due to many diseases, cultivated plots are often not harvested. Watermelon Fusarium wilt, in particular, is a serious disease in continuous cropping, which requires rotation. Self-rooted seedlings in the same plot should be rotated at least once every five years. Crops before watermelon are wheat, corn, sorghum, rice and sugarcane, so avoid stubble. 2. Cultivation techniques 1. Sowing in time: Sow in protected land in the middle and late March in northern Zhejiang, and sow in the middle and late March in southern Zhejiang. The seedlings are about 30 days old and transplanted in the open field. The outdoor live broadcast will be held 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 make 500 times solution with 50% carbendazim and soak watermelon seeds in it 1 hour, which can also achieve the purpose of disinfection and sterilization. 3. Accelerating germination: Soak the seeds two days before sowing to accelerate germination, soak the sterilized seeds in clear water at room temperature for 4 hours, then wrap the seeds with gauze and rub them in warm water until the water is clear. Wipe off the water and soil 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. It is advisable to spread the seeds with a thickness less than 3cm, then cover them with 2-3 layers of wet cloth, put them in an enamel pot or other container, and then put the container in a thermostat or other heat source. Keep the temperature in the pile at about 30℃, and turn it once after 20 hours to make the seeds heated evenly. When covering the 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 0.5 cm. Pay attention to watering the soles of your feet before sowing, and the seeds should be 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 being covered with plastic film, the seeding holes form a small greenhouse. Just after the seeds touch the soil, a small hole is dug in the top film of the greenhouse. With the increase of external temperature, the holes gradually expand until the melon seedlings are led out of the film and sealed with soil pressure film. Don't lean on the stem to prevent high temperature burns, which may lead to illness or seedling death. 5. Seedling raising: seedling raising in greenhouse or small arch shed with nutrition bowl is convenient for seedling management, sowing time is advanced, and it is easy to ensure the whole seedling after planting. Nutritional plastic bowls can also be made of paper or plastic film, with a height of 10cm and an upper diameter of 8- 10cm. (1) Preparation of nutrient soil: nutrient soil should be rich in nutrients and have good permeability. Usually made of one third of decomposed fertilizer and one third of plant ash. According to different soil and fertilizer textures, the proportion of ingredients can be changed appropriately. Water to moderate humidity, hands are not hard to hold together, loosen and bond. Each cubic meter of nutrient soil should also be added with 2 kilograms of phosphate fertilizer or three-no compound fertilizer, and fully mixed. (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 in the seedbed. Water the seedbed, put the germinated seeds in the center of the nutrient basin, one in each basin, and cover with 1.5-2 cm moist nutrient soil. (3) Seedling management: Before the seedlings are unearthed, it is mainly to keep warm and moisturize. The temperature of seedbed should be kept between 25-30℃ to promote the rapid excavation of seedlings. After the seedlings are planted, it is easy to grow in vain until the first real leaf appears. Timely and proper ventilation is the main preventive measure. During this period, the bed temperature should be reduced from 22 ~ 25℃ during the day to 15 ~ 18℃ at night. After the appearance of the first true leaf, it is known 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 raise seedlings according to the weather conditions. When raising seedlings, the illumination time of the seedbed should be extended as much as possible within the temperature range to make the seedlings grow vigorously. 6. Land preparation: there are many areas in the southeast coastal areas. Watermelon planting should be ridged to prevent water accumulation in the field, and the general row spacing is 2.5m-3m. Combined with soil preparation, farmyard manure and chemical fertilizer should be applied in layers. 667m2 of fully decomposed farmyard manure is about 1500kg. According to soil fertility, apply ternary compound fertilizer 15-50kg, phosphate fertilizer 50kg and potassium sulfate 10-20kg. 7. Planting: When the outside daily average temperature is stable above 14℃ and the watermelon seedlings have three leaves and one heart, it is the suitable time for watermelon planting. Planting density varies with soil fertility and variety. Generally, there are 400~450 large fruit varieties /667m2 and 500 medium fruit varieties /667m2. Before planting, holes should be punched on the ridge surface covered with plastic film according to the plant spacing, and the aperture is the same as that of the nutrition bowl, with a general aperture of 10cm and a depth of 10cm. Before transplanting, pour the nutrition bowl thoroughly, 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. Direct planting, surrounding soil, gentle pressure. If the soil is dry when transplanting, water it. 8. Pruning: Watermelon pruning forms include one vine, two vines, three vines and many vines.