The method of grafting grafted watermelon seedlings by top insertion method has many disadvantages for factory production. In 2001, China introduced a new grafting technology, that is, the method of cutting off the root graft, and changed the method of traditional grafting using the root system of the rootstock. In order to remove the root system of the rootstock and induce graft healing, new roots were induced in the rootstock. The cutting-root grafting method has proved to have many obvious advantages in the demonstration and promotion. The seedlings produced by the method of cutting off the roots are thick, uniform in growth, and the root systems are well developed after planting. Watermelon cutting root grafting seedling technology has been widely applied in factory cultivation seedling production in China. The production of watermelon grafted seedlings of Chuanhua Dadi Group basically adopts the method of root grafting.
First, rootstock and scion sowing date
The use of gourds as root stocks should be sowed two days earlier than the scion.
Second, soaking and germination
1. Rootstocks: Rootstock seeds should be sunned for 2-3 days before sowing. They should be soaked with warm water of 55-60°C before sowing. When soaking, they should be continuously stirred until the water temperature drops to 30°C. After cooling, they are soaked in 2% bleach solution for 15 minutes. Clean and then soaked with water for more than 16 hours, then wash 2-3 times until sowing.
2. Scion: Before sowing, use 55-60°C warm water to soak seeds and disinfect them. The water temperature should be washed 2-3 times after being cooled naturally, soaked for 6-8 hours and then washed 3-4 times until sowing.
Third, sowing
1. Rootstocks: Use a 45 cm and 45 cm seedlings to plant the seedlings. Spread a 3-5 cm thick, well-sterilized, seedling-specific substrate in the pan. Seed sown after compaction. The row spacing is 5 cm. Plant spacing is 1.5- 2 cm, seed direction is consistent, about sowing 220-230. Then use a sterilized fine sand to cover about 1.5 centimeters, fully watered and placed in the germination room at 28-30 degrees Celsius to germination, when the arboreal moved to nursery greenhouse.
2. Watermelon: Use the same square plate to spread 3-5 cm thick substrate first. Watermelon seeds should be sowed on top. Then cover the substrate with 2 cm or so. Place it in the germination room at 28-30°C after watering. Pay attention to watering. Should not be too much, otherwise it will affect the seed germination. After germination, see the light in time for shelling, but the light should not be too strong.
IV. Pre-grafting management
1. Rootstock: Before the emergence, the sand should not be dried. When the seedlings are out, the water should be controlled in due time. The general principle is to water the sand in the morning and see the sand in the evening. Before the grafting, pests and diseases should be prevented and treated. In general, 75% chlorothalonil 800 times solution should be sprayed on the cotyledon flats, and 70% thiophanate-methyl 800 times solution and 72% agricultural streptomycin 4000 times solution should be sprayed on the day before grafting.
2, watermelon in the germination room after germination promptly fill light, spray water, Qi seedlings into the nursery greenhouse to see the natural light, the substrate should not be too dry, spray 1 time before grafting 70% thiophanate-methyl 1000 times.
V. Grafting
1. Suitable period for grafting: The true size of the rootstock is the same as the five-centimeter coin; the watermelon leaves are flat.
2. Preparation: Rootstocks are budded one day before grafting, and irrigated 0.5-1 hour before grafting. When watering watermelon seedlings, spray water. Before cutting, the seedbed in the surviving area should be disinfected and warmed up 1 hour earlier. Fix a worker to cut rootstocks and watermelon seedlings.
3. Grafting method: The rootstock is cut off from the cotyledon 5 cm below, and the watermelon seedling is cut off at the bottom. When grafting, use a special grafting sign to insert and remove the grafting mark obliquely downward from the vertical part of the vertical cotyledons of the rootstock. The depth is 0.5 cm to avoid uncovering the epidermis. Watermelon seedlings are cut along the front and back of the stalk in the direction of the stalks, and should not be too thick. Cut the knife at 0.5 cm and quickly insert the rootstock. After grafting, put it in the carton and moisturize until it is cut.
4. Cutting: Choose 72 seedling plug trays for common nursery substrate, and dip the grafted seedlings after dipping into the bottom water. The cutting depth is about 3 cm. Immediately after cutting, it is placed in the seedbed of the living area.
5. Grafting points: Grafting personnel, cutting personnel, cutting seedlings and logistic personnel are to be determined the day before grafting. Operational quality inspection personnel should be arranged during large orders to guarantee the quality and quantity of grafting on the same day; preparatory work before grafting, including grafting tools, Towels, grafting trays, disinfectant and grafting labels.
Six, survival management
1. Temperature: 3 days after grafting, the temperature requirement is relatively high, during the day 26-28 °C, 22-24 °C at night, when the temperature is higher than 32 °C, it should be ventilated and cooled, and in the next few days, the temperature should be appropriately reduced by 2-3 °C according to the wound healing condition. . 8-10 days after entering the normal management of seedlings.
2. Humidity: The humidity of the first two days after grafting requires more than 95% of the humidity. When the humidity is low, spray humidification. As the ventilation time increases, the humidity gradually decreases to about 85%. After 7 days, normal seedlings humidity management was approached according to healing conditions.
3, light: two days after grafting to shading, see the natural light sooner or later a few days later, in the management as the situation gradually lengthened the light time, allowing mild wilting. 8-10 days can completely remove the shade net.
4. Ventilation: Under normal circumstances, two days after grafting, it shall be closed and not ventilated. Only when the temperature is higher than 32°C can it be ventilated. Ventilation begins on the third day after grafting. The first is ventilation in the morning and evening. Afterwards, the ventilation volume and the ventilation time are gradually increased. , Spray water before wilt film cover. 8-10 days after entering the normal management of seedlings.
VII. Management after survival
1, fertilizer and water management: timely control of water after survival, is conducive to promoting root development. Under normal circumstances, first apply fresh water first, and then apply nitrogen, phosphorus, and potassium to fertilizers of 15%, 0.15% and 20%, 10%, and 20%, respectively, and dilute the concentration between 50-120 cm/kg. Use alternately. Water and fertilizer before shipment should not be too much, easy packing and transplanting seedlings.
2, in a timely manner to sprout: The rootstock sprouts rapidly under high temperature and high humidity environment, affecting the normal growth of watermelon seedlings, so should be promptly removed after survival.
3, hardening seedlings: 5-7 days before delivery to reduce the temperature of 2-3 °C, and to control the fertilizer.
4. Pest control: Pest prevention after grafting is very important, and it is necessary to spray pesticides on a regular basis. Diseases at the seedling stage mainly include damping-off, epidemics, anthrax, powdery mildew, leaf spot, and downy mildew. You can choose 70% thiophanate-methyl 800 times, 70% mancozeb 800-fold, 75% Chlorothalonil 600-800 times solution, 25% metalaxyl 1500 times solution, 64% antivirus 600-800 times solution, 30% Tetracycline 3000-5000 times solution, 10% Shigao 2500-3000 times solution, 72 % Streptomycin 4000-5000 times of agricultural streptomycin, insecticide fungicides alternating use, spraying once every 7-10 days, the control effect is very good.
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