Latest Technical Method Tutorial for Cucumber Grafting
Cucumber grafting is a cultivation method in which the cucumber roots are replaced by pumpkin roots. Because pumpkin roots are well developed, tolerant of low temperatures and resistant to high temperatures, and not susceptible to soil-borne diseases, the cucumber plants grow vigorously, and it has a preventive effect against many diseases, especially Fusarium wilt, and brings early maturity and high yield.
Variety selection and seed soaking for sprouting
The main variety is black-seeded pumpkin (Cucurbita ficifolia), with a seeding rate of 1.5 kg per mu, and 4400-4700 seeds per kg. Before sprouting, the seeds should be dried in the sun for 1-2 days, soaked in warm water for 6 hours, rubbed and washed 3-4 times, and after soaking, dried at room temperature of 12-14 degrees C for 18 hours to make the seed coat dry, then sprouted at 30 degrees C, and germination begins in 2 days.
Grafting methods
1. Approach grafting. First sow cucumbers in beds, and sow pumpkins 5 days later. Pumpkins are sown in nutrient pots. The nutrient soil in the pots can be filled to 70 percent of the height. Pumpkin seedlings emerge in 2-3 days, and after about 10 days, when the pumpkin has grown to one true leaf and one heart leaf, grafting begins. Before grafting, first make a bamboo stick; the bamboo stick is whittled from a bamboo strip, with the handle part flat and the very tip cylindrical, and the smooth surface of the bamboo strip below the tip whittled into a blade. When grafting, first use the blade part of the bamboo stick or a razor blade to remove the pumpkin growing point from the cotyledon area, and use the tip of the bamboo stick to make a scratch at the lateral buds at the base of the two cotyledons to prevent lateral buds from growing. At 0.5 cm below the pumpkin growing point, use a razor blade to cut downward a slant about 1/2 of the stem thickness. For the cucumber, cut upward at 1.5 cm below the growing point a slant about 2/3 of the stem thickness. The slant length of the cuts on both cucumber and pumpkin is about 1 cm. Insert the two cuts into each other so they fit together. Clip a grafting clip at the joint, then add some bed soil into the nutrient pot, cover the cucumber root system and water thoroughly, and enter the late-stage grafting management. After 10 days, use a blade to cut off the cucumber root and remove the clip.
2. Root-cut approach grafting. Sow cucumbers after the pumpkin seedlings emerge, which can save the root-cutting step. Grafting begins when the pumpkin has grown to one true leaf and one heart leaf. The pumpkin cut and the method of removing the growing point are the same as for approach grafting. For the cucumber, at 1 cm below the growing point, insert it into the pumpkin cut so they fit together. Clip a grafting clip at the joint or wrap and tie it with a strip of plastic film.
3. Horizontal insertion grafting. This method also involves sowing cucumbers after the pumpkin seedlings emerge, saving the root-cutting and grafting-clip steps. When the pumpkin has grown to one true leaf and one heart leaf, remove the growing point, and at 0.5 cm below the growing point, use a bamboo stick slightly thicker than the cucumber stem to pierce vertically through the pumpkin stem, with the bamboo stick protruding slightly. For the cucumber seedling, when the cotyledons are fully expanded, cut a 30-degree slant at 1-1.5 cm below the growing point, and insert it downward, cut side facing down, into the insertion hole in the pumpkin stem. Choose thick, strong cucumber seedlings for this; do not use leggy seedlings.
4. Slant insertion grafting. The sowing of pumpkin and cucumber and the size of the seedlings are the same as for horizontal insertion grafting. First use the tip of a bamboo stick to make a slightly penetrating hole slanting at a 45-degree angle to the stem on one cotyledon side of the pumpkin, then cut a cucumber seedling with just fully expanded cotyledons at about a 30-degree slant at 1 cm below the cotyledons, and insert it downward into the slant insertion hole in the pumpkin stem.
Management after grafting
After grafting, the cucumber seedlings are best placed on lower shelves in the greenhouse; if placed on the ground, first spread straw. Then water thoroughly and spray 800-fold chlorothalonil solution to prevent disease. Cover the seedlings with a small arched tunnel so that the humidity in the first 3 days can reach saturation, that is, water droplets appear on the film on the second day after covering, and the film must be sealed tightly. Cover the small arched tunnel with paper quilts to shade the light so that the seedlings do not see light in the first 3 days, but be careful to open the tunnel to check, re-align cuts that have not matched up, and re-graft cucumber seedlings that have wilted. Through heat preservation or heating, make the daytime temperature in the first 3 days reach 25-30 degrees C and the nighttime temperature 15-20 degrees C. On the 4th day after grafting,
expose to light for 1 hour in the morning and evening each. On the 5th day, 2 hours each; on the 6th day, 3 hours each; on the 7th day, full light can be given. At this time, remove the lateral buds that were not cleaned off from the pumpkin cotyledons.
The survival rate of grafting is closely related to post-grafting management, especially the humidity in the first 3 days, which must reach saturation with no light.
Precautions for grafting
1. Sow earlier. Grafted cucumbers have a seedling-recovery process; pumpkin roots tolerate low temperatures and can be planted early, so sow about 10 days earlier, otherwise early maturity will be affected.
2. Ethephon treatment. The temperature required for grafted seedling recovery is relatively high, which raises the node position of cucumber fruit set and reduces the number of fruits. Therefore, ethephon treatment is needed to lower the fruit-setting node position and increase the number of fruits. The method is, when the cucumber has grown 1-2 true leaves, spray the leaves with 100 ppm ethephon, and spray again after 1 week. In addition, pay special attention that if it is a first-generation hybrid cucumber variety, ethephon treatment is not suitable, because it itself usually has very strong fruit-setting ability, and treatment will instead cause the flower-topped phenomenon.
3. Use ecological control for downy mildew as much as possible. Grafting basically eliminates vine-cutting disease (Fusarium wilt), but other diseases and downy mildew cannot be directly controlled, so ecological control should be adopted, using four-stage variable-temperature management to create temperature and humidity conditions unsuitable for the occurrence of downy mildew, combined with chemical control.
4. Apply more compound fertilizer. Grafting allows continuous cropping for many years, but it often leads to an imbalance in soil nutrient ratios and a lack of certain nutrients. Therefore, apply more farmyard manure and compound fertilizer. For example, add 1 tube of Yemianbao and 0.5 kg urea to 50 kg water for foliar topdressing.