In 2002, the Beijing Vegetable Research Center carried out a large-scale watermelon root-grafting technology promotion in the West melon demonstration area of ​​Panggezhuang, Daxing District. The demonstration zone successfully used the root-separation grafting method to successfully grow 1 million commercial seedlings in spring. The success of this technology depends on The staff at the base strictly followed the technical regulations developed by the author. The technical regulations to be formulated are summarized below for reference by technicians and farmers. First, use 50 plug tray rootstock, scion use of 288 holes, 128 hole plug or plastic seedling plate, cut grafted grafted seedlings inserted in 50 plug tray. Second, the matrix matrix can choose to use peat, vermiculite, perlite, with a ratio of 3:1:1, the matrix ratio formulated in volume ratio. Add 100g carbendazim or 200g chlorothalonil per cubic meter of substrate and mix well for matrix disinfection. Third, the selection of rootstock stocks Rootstocks are mainly used for melon and pumpkin. Commonly used squash varieties include Jingxin Anyuan, Qianggang No. 1, Nanyang No. 1 and Qiang Gang No. 2. Commonly used varieties of squash include Jingxin No. 2 and black-skinned squash. 4. Seed treatment and sowing methods Seed disinfection and soaking and germination should be carried out before sowing. The method is: soaking seeds with 100% solution of formalin for 30--60 minutes, or 500--600 times of 50% carbendazim. The solution was soaked for 60 minutes. The sterilized seeds were rinsed with clean water and soaked in clean water. Can also be soaked in warm water, rootstock seeds and watermelon seeds can be used 55--60 °C warm water soaking, soaking process must be constantly stirred, then soaked in 25 - 30 °C water temperature, rootstock seeds soaked 12 - 24h after the seeds removed Seed coat mucus, rinse with water 2 - 3 times, can be wrapped with a damp cloth, germination at 28 - 30 °C conditions. When the radicle on the seed extends about 3min, it is planted in a 50-hole plug tray. The temperature is kept at room temperature 28--30°C during the day and 18--20°C at night, and the substrate temperature is maintained at about 21°C. When 70% of the seed is arched, the temperature is lowered, and the temperature is 20-25°C during the day and 15°C at night. The temperature of the substrate is maintained at about 17°C. During this period too high temperature can easily lead to seedlings leggy, too low when the cotyledon drooping, decaying roots or tripping, pay special attention to cloudy temperature management do not appear low night high reverse temperature difference. The scions were soaked when the rootstock grew to the first true leaf spit, and germinated 6-8 hours later. When the shoot length was 2mm, they were sown in 288-well, 128-well plug trays or plastic seedlings. After sowing, the temperature was kept at 28--30°C during the day, 15-18°C at night, and the temperature of the substrate was maintained at about 21°C. The first true leaf of the rootstock was flat and the cotyledons were grafted when flattened. V. Grafting methods and field management Grafting methods are cut at about 6cm below the rootstock cotyledons, and the true leaves and growing points of the rootstock are removed. A 3mm thick bamboo stick is used, and one end is sharpened to a semi-conical shape with a length of 1cm. 5mm diameter and diameter of watermelon seedling hypocotyl is equivalent, about 2.5mm, the scion cutting a knife at 1cm below the cotyledon. When grafting, the bamboo stick will be obliquely inserted 5mm deep from the rootstock leaf, and the epidermal hypocotyl epidermal Make a slight break, then insert the sharpened scion and insert it tightly. After grafting, the grafted seedlings were inserted into a water-drenched plug, the depth was about 3cm, the air temperature after grafting was kept at 28--30°C, the temperature of the substrate was kept at 21-25°C, and the film was grafted on the grafted seedlings to block the light for the whole day. Humidity is adjusted to more than 95%. After about 3 or 4 days, it began to reduce the shading time, and gradually increased ventilation. After 1 week, temperature and light management returned to normal and the substrate temperature was maintained at 17--21°C. Afterwards, the temperature management grew as the grafted seedlings grew and the night temperature gradually decreased. When the watermelon seedlings grew to 2 leaves and 1 heart, the night temperature remained at 15-16°C, which was favorable for the differentiation of female flowers. Seedling water management should maintain 75%-80% of the maximum water holding capacity of the nursery substrate. Too little water in the matrix will promote the formation of male flowers and cause flower topping. In principle, water temperature is not controlled during seedling period. Before the planting, exercise at low temperature, during the day 22--24 °C, 13--15 °C at night is appropriate. After the grafting, the nutrient solution was poured according to the growth condition of the grafted seedlings, and the nutrient concentration was N: 150--400 mg/kg; P2O5: 200--450 mg/kg; K2O: 570--800 mg/kg: Ca: 50--80 mg/ Kg; Mg: 20--25 mg/kg. Sixth, pest control rootstock and scion after the emergence of Spray 400 grams of -600 times the liquid to prevent the occurrence of damping-off, the day before grafting, the rootstock and scion seedlings sprayed 15% 75% chlorothalonil WP 800 times. Spraying agrochemical streptomycin 200mg/kg on the 5th day after grafting to prevent rotten seedlings. After spraying germicide every other week, it can also be sterilized with chlorothalonil aerosol 1--2 times in the breeding greenhouse to prevent diseases. occur. Pests can be selected according to the occurrence of the corresponding agent for prevention and treatment. VII. Commodity seedlings are planted after 20--25 days after standard grafting. The roots are thick and well developed. The height of the plant is about 15cm, the stem diameter is 3.5-4mm, and there are 3--4 true leaves, and the leaf area reaches 20--30. Square centimeters can be sold as commodity seedlings. China Agricultural Network Editor