① Determine the seedling stage. In the case of greenhouse cultivation, when the soil temperature is stable at 65438 05℃ and the temperature in the greenhouse is not lower than 65438 05℃, it is generally 65438 05℃, and the seedling emergence and sowing date will be advanced by 25 ~ 30 days. Greenhouse cultivation can be carried out 45 ~ 50 days in advance.
② Preparation before seedling raising. Watermelon cultivated in greenhouse can be sown 45 ~ 50 days in advance. During this period, the northern region planted seeds at 65438+ from the end of June to the beginning of February. At this time, the outside temperature is very low, which is not suitable for the growth of watermelon seedlings. Therefore, heating equipment must be used to ensure the temperature required for seedling stage. There should be heating equipment before seedling raising.
A. raising seedlings in greenhouse. If conditions permit, you can use a heating greenhouse, that is, a back wall with a fire path for indoor heating, or you can use a solar greenhouse and use geothermal lines to raise seedlings.
No matter heating greenhouse or sunlight greenhouse, it is necessary to cover the film about 15 days before seedling raising to improve the ground temperature and air temperature in the greenhouse. Cover the grass curtain at night to prevent the heat loss in the greenhouse.
B. preparation of nutrient soil in nursery. The structure and composition of nutrient soil directly affect the growth of watermelon roots and seedlings. There should be no germs, eggs and weeds, fertile soil, comprehensive nutrition, loose texture, and water and fertilizer conservation. Grasp the tightness when preparing. When transplanting is too loose, it is easy to break and damage the root system, which affects the survival. Too tight actually affects the normal growth of hair roots and seedlings.
Nutrient soil can be made from vegetable garden soil, paddy field topsoil, weathered pond mud, furnace ash, cattle, horse, pig manure and poultry manure in a certain proportion. The specific proportion can be flexibly grasped according to the local soil conditions, and it is best to compost it three months before use, mix it evenly and use it after screening. When necessary, a small amount of chemical fertilizer can be added to the nutrient soil, but the dosage must be controlled and mixed well with the soil to avoid burning the roots. Its dosage is 0.25 kg urea, 1 kg calcium superphosphate, 0.5 kg potassium sulfate or 1.5 kg nitrogen, phosphorus and potassium ternary compound fertilizer per cubic meter of bed soil.
When necessary, the bed soil should be disinfected. The common method of soil disinfection is to use 200 ~ 300ml of 40% formalin per cubic meter of culture soil, add 25 ~ 30kg of water, stir evenly, sprinkle it into the soil, cover the soil with plastic film for 2 ~ 3 days to achieve full sterilization, and then spread it out to give off medicine gas before use, which can prevent sudden collapse at seedling stage. Pouring 800 times 90% crystal trichlorfon on the bottom of the seedbed can effectively prevent the harm of earthworms and crickets.
③ Seed treatment and sowing before sowing.
The growth of watermelon at seedling stage is related to fruit setting in the later stage, which is the main condition affecting yield and quality. Therefore, seedlings are the foundation, and cultivating a strong seedling is the key to the whole growth period.
Criteria for strong seedlings: suitable seedling age, complete cotyledons, thick and short hypocotyls, flat and thick cotyledons, short internodes, dark green leaves, stretched roots and white and tender; Anatomically, the tissues are closely arranged and the protective tissues are developed; Physiologically, tissue water content is low, cell fluid concentration and sugar content are high. The seedlings with the above characteristics have cold tolerance, strong adaptability, high physiological activity and quick seedling delay after planting.
Cotyledons are the main source of nutrition and energy in the early stage of watermelon seedlings. It stores a lot of nutrients and provides energy for seed germination and seedling growth. Cotyledons are the main organs assimilated after excavation. Although it is very small, its photosynthetic efficiency is stronger than that of growing plant leaves, which provides nutrition for seedling root growth and leaf and flower differentiation and plays a decisive role in seedling growth. Therefore, it is of great significance to ensure the normal growth and long-term maintenance of cotyledons.
A. soak seeds to accelerate germination. Soak the seeds in warm water at 55℃, stir 15 minutes, soak for 6-8 hours, and put them in a thermostat at 28-30℃ to accelerate germination. Wash with clean water 1 ~ 2 times a day. The gauze or towel used to wrap seeds should not be too wet, just keep it wet. When the humidity is too high, the seeds absorb too much water and are easy to rot. The factors affecting germination are temperature, moisture and gas, so the three conditions of temperature, moisture and gas should be adjusted well when germination. Qi is used to supplement oxygen by changing water in the process of germination, which promotes rapid and uniform germination. Generally speaking, Xin Jing 1 watermelon germinates at 30℃, 75% in 24 hours and over 90% in 48 hours.
B. sow seeds. Before sowing, make a good seedbed, put the prepared nutrient soil into a 8 cm nutrient bowl or a nutrient paper bag, lay it flat and arrange it closely, so as to water evenly, keep warm and keep water, and prevent the paper bowl from breaking. After putting it away, fully water it to ensure the water demand at seedling stage, sow it after underwater infiltration, germinate a bowl of seeds, with radicle facing down and seeds lying flat. After sowing, cover the sieved moist pastoral soil with the same thickness, which is about 1 cm. Too shallow, the topsoil is easy to dry, and the seeds are easy to "wear hats", which affects the development of cotyledons and seedlings. Do not water after sowing and covering the soil, and keep the soil loose.
After sowing, cover the seedbed with a small arch shed to maintain humidity, raise temperature and promote seedling emergence. If the geothermal line is used to raise seedlings, cover the shed with electricity after sowing and keep the ground temperature at 18 ~ 20℃. Cover the shed with straw curtains at night to keep the temperature inside the shed.
Generally, seedlings can emerge 4-5 days after sowing. When the seedlings break the soil, cracks appear in the nutrient bowl, and water is easy to be lost. It is necessary to cover them with a layer of sieved and moist fine soil in time. And open the shed during the day to avoid burning seedlings at high temperature.
④ Key technologies that should be paid attention to in seedling management.
A. temperature management. Temperature change management should be adopted. From sowing to germination, higher temperature is needed to accelerate the emergence of seedlings, so the seedbed should be closely covered, and the temperature of the seedbed should be increased by full illumination during the day, and the ground temperature should be increased by using a hotline at night, and covered with a straw curtain for insulation. Before excavation, the temperature in the shed was 28 ~ 30℃, and the soil temperature was above 65438 08℃. After emergence, the temperature should be reduced appropriately, and it should be kept at 20 ~ 25℃ during the day and at 15 ~ 18℃ at night. If the seedbed temperature is too high during this period, the hypocotyl will be elongated, which will easily form "tall seedlings" and the growth potential will be weak. After the true leaves are unfolded, the hypocotyl will not be excessively elongated, and the temperature can be appropriately increased, and kept at 25 ~ 28℃ during the day and at 18 ~ 20℃ at night to accelerate the growth of melon seedlings. About a week before planting in the field, the bed temperature should be gradually lowered, and the film should be uncovered for outdoor exercise to improve adaptability.
The hotbed of electric hot wire is heated by sunlight during the day, and the soil temperature is controlled at 18 ~ 25℃ before sowing, and electric heating is used in cloudy days and at night. Heat it for 4-6 hours every evening before the true leaves appear, and control it at18-22℃. If the outdoor temperature rises after the first real leaf appears, there is no need to heat it.
The ventilation of seedbed should be gradually increased. First, uncover the membranes at both ends, and then open the air outlet at the side. Vents should be leeward to prevent cold air from blowing directly on seedlings. Pay close attention to the bed temperature on sunny days, and let the air cool down in time to prevent seedlings from being injured by high temperature. Two tendencies should be avoided in temperature management of seedbed. One is that the temperature of the seedbed is too high, and the seedlings are weak and have poor adaptability. The other is to emphasize the cooling movement unilaterally and uncover the film prematurely. The seedlings grow slowly under the influence of low temperature, and in severe cases, stiff seedlings and "old seedlings" appear. The correct method is to master flexibly according to the above principles and the climatic conditions at that time, and to require the seedling age to reach 3-4 true leaves (referring to self-roots) within 30-35 days.
B. light The light transmittance of plastic film is about 70%. If the cover is tight, the relative humidity of the air will reach saturation and the light transmittance will be lower. Therefore, we should strive for more light in management. If a new film is used, the cleanliness of the film surface is maintained and the light transmittance is increased; Uncover the film early and cover the film late within the allowable range of bed temperature to extend the illumination time; Proper ventilation can reduce the humidity of seedbed; Uncovering the film on a warm sunny day can effectively improve the lighting conditions of the seedbed. In continuous rainy days, try to ventilate as much as possible, for example, ventilate with bricks or wooden sticks at a certain distance from the bed side to cool down and increase the light.
Using heating greenhouse or sunlight greenhouse to raise seedlings. When the seedlings are unearthed, open the shed and straw curtain during the day to increase the light time.
C. moisture. The watering of seedbed should be strictly controlled in the early stage, because the seedbed is fully watered before sowing. After sowing, the seedbed is mainly insulated, and the water evaporation is not great. Watering will reduce the temperature of seedbed and increase humidity, which will easily lead to seedling overgrowth and diseases. Fine soil can be used to reduce water evaporation. When the topsoil turns white and cracks appear, it can cover fine soil, increase soil surface humidity and protect roots. Cover the seedlings when they are in full bloom.
In the middle and late stage of seedling raising, the temperature is relatively stable, the ventilation increases, and the soil evaporation increases accordingly. Seedling true leaves 1 ~ 2 pieces, which can be properly watered and replenished. Water is usually cooked at noon on sunny days, and the amount of water should not be too much. After watering, cover with a film after the water on the plant surface evaporates to avoid the high humidity of the seedbed. Watering before planting 1 time. This time, we should fully water it to prevent the loose roots from affecting the slow seedlings.
Watermelon has a short seedling stage and does not need multiple fertilization. Usually no more topdressing. However, the low temperature and insufficient illumination during seedling raising, especially the rainy days in the south, lead to slow seedling emergence, slow seedling growth and long seedling stage. If the nutrient soil for seedling is not fertile, the seedlings will be thin and yellow, and the true leaves will be too small to stretch out. It is necessary to supplement nutrition by spraying fertilizer on the leaves or irrigating the roots to make the seedlings grow healthily. Spraying can use 0.3% urea and 0.2% potassium dihydrogen phosphate as topdressing outside the roots, and can also use biological agents such as foliar treasure and spraying treasure as topdressing outside the roots.
D. pest control. The main diseases at seedling stage are damping-off, anthracnose and aphids. Disease prevention is the mainstay, and seedbed management mainly controls humidity to prevent the occurrence of damping-off disease, epidemic disease and anthracnose due to excessive humidity. If it happens, 800% Du Rui EC should be used to irrigate the roots to prevent and control Rhizoctonia solani. Control anthracnose with 600 ~ 800 times thiophanate methyl. 1500 ~ 2000 times omethoate mixture to control aphids.
(2) Grafting and seedling raising.
① The necessity and advantages of watermelon grafting seedling.
In recent years, the cultivation area of watermelon protected land in Beijing has increased year by year, and the problem of continuous cropping has become increasingly prominent. Long-term continuous cropping will worsen the soil environment and lead to serious occurrence of soil-borne diseases and insect pests such as Fusarium wilt and nematodes. Usually, measures such as crop rotation, soil disinfection and pesticide irrigation can be adopted to solve the obstacles of continuous cropping. Crop rotation, soil disinfection and pesticide irrigation have a long cycle, which not only causes a lot of pesticide residues, but also has high cost. Grafting and root-changing cultivation technology is an important way to solve soil-borne diseases and continuous cropping obstacles of watermelon at present. Grafting watermelon can not only reduce the occurrence of diseases and insect pests, but also improve stress resistance, fertilizer and water utilization rate, increase yield and improve quality. It is a technical measure to increase watermelon production and income, with short cycle, less investment and quick effect.
The advantages of grafting cultivation are as follows:
A. overcoming continuous cropping obstacles and improving disease resistance. Grafting seedling is to select melon crops that are resistant or immune to watermelon Fusarium wilt as rootstocks to achieve the purpose of disease resistance and even immunity. In addition, the commonly used rootstock varieties have strong resistance to soil-borne diseases and insect pests, so the stems and leaves of grafted seedlings grow vigorously, the stress resistance is enhanced, and the harm degree of some diseases in stems and leaves is often reduced.
B. improve the utilization rate of fertilizer and water. Because rootstocks are all wild or cultivated varieties, the root system is developed, the ability to absorb fertilizer and water is stronger than that of cultivated self-rooted watermelon, and the root system is widely distributed, so that water and nutrients can be utilized in a larger soil volume range. In addition, rootstocks have strong fertility absorption, so the growth of aboveground parts increases correspondingly, the leaves become thicker, the leaf area increases, and photosynthesis is strengthened. Therefore, to achieve the same growth potential, it is necessary to reduce the amount of fertilization, which is 20% ~ 30% less than that of self-rooting, thus improving watermelon.
C, the stress resistance of watermelon is enhanced, and the yield increase effect is obvious. Most grafted plants show strong growth potential, and their adaptability to low temperature, drought or humidity, strong light or weak light, saline-alkali or acidic soil is higher than that of ungrafted watermelons. Early spring can be sown early, with longer fruiting period and more obvious yield increase. Generally, the yield per mu can be increased by over 30%. For example, grafted watermelon can increase production by 30% ~ 50%.
D. it can improve the quality and flavor of fruits. As long as the appropriate rootstock is selected, the quality of the grafted fruit will not decrease, and the quality and flavor of the fruit can be improved. For example, the grafted watermelon has increased sugar content, geometric shape, good appearance and bright and delicious flesh.
E. save labor, trouble and cost. Using grafting technology to plant watermelon does not need to stubble again, which saves land resources, and the technology is simple and easy to learn, master and apply.
F, preserving propagation materials and expanding propagation coefficient. In the case of rare or few propagation materials, in order to avoid accidental loss, branches or shoots can be grafted on suitable rootstocks to cultivate plants, so as to preserve the materials and expand the propagation coefficient.
② Preparation before grafting.
The following preparations must be made before watermelon grafting:
A. preparation of grafted rootstock and scion seeds. Before watermelon grafting, the seeds of rootstock and scion needed for grafting should be prepared in advance according to the requirements of different grafting methods.
B. select the appropriate grafting site. Watermelon grafting has strict requirements on the grafting site. Appropriate conditions such as temperature, humidity and light should be made in the site to ensure the survival rate of grafted seedlings.
C. prepare the tools needed for grafting. The appliances needed for watermelon grafting mainly include sunshade nets, trays, watering pots, blades, bamboo sticks, grafting clips, clean water, disinfectants, wooden boards and benches.
D, seedbed preparation and nutrient soil configuration. According to the way of raising seedlings, select the appropriate seedbed, and configure high-quality nursery nutrient soil according to the growth and development characteristics of watermelon rootstocks and scions and the requirements for nutrition.
E, prepare seedling pots and trays. According to the needs of watermelon grafting rootstock and scion, prepare seedling pots and trays with appropriate sizes. Generally, grafted rootstocks of watermelon will be planted in seedling pots, and grafted scions of watermelon will be planted in seedling trays.
(3) Selection of watermelon grafting site.
Watermelon grafting site should be carried out in solar greenhouse or plastic greenhouse, and the grafting site should maintain a certain temperature and humidity to avoid seedling wilting. Pay attention to the disinfection of related appliances when grafting, and keep the grafting parts clean and tidy. The specific requirements are:
① temperature. The temperature of grafting site is 25 ~ 30℃ during the day, 18 ~ 20℃ at night, and the ground temperature is 22 ~ 25℃. Because the temperature is too high, it is easy to cause the grafted seedlings to lose water and wilt, which reduces the survival rate of grafted seedlings. Too low temperature affects the wound healing of grafted seedlings and also affects the survival rate of grafted seedlings. For places where the ground temperature can't reach, we can increase the ground temperature by increasing geothermal lines to meet the temperature requirements of grafted seedlings.
② Humidity. The relative humidity of the air at the grafting site must be kept above 90%. Because high humidity is beneficial to the wound healing of grafted seedlings, if the humidity is too low, it is easy to cause the grafted seedlings to lose water and wilt, reducing the grafting survival rate.
③ illumination. Grafting parts should not be exposed to direct sunlight. In the process of grafting operation, we must pay attention to avoid direct sunlight, because direct sunlight can easily lead to dehydration and wilting of grafted seedlings, thus affecting the survival rate. We can take the measure of covering the shed film with a sunshade net to keep the scattered light and meet the lighting requirements of grafted seedlings.
(4) Grafting equipment required for watermelon grafting.
The appliances needed for watermelon grafting mainly include: sunshade net, tray, watering can, blade, bamboo stick, grafting clip, clean water, disinfectant, wooden board, bench and so on.
① sunshade net. Covering the outside of the greenhouse film plays the role of shading and cooling, and prevents grafted seedlings from dehydration and wilting due to direct sunlight.
② Tray. Used for rootstocks, scions and grafted watermelon seedlings. If there is no tray, plastic boxes can be used instead.
Three small watering cans. Used to spray water on grafted seedlings. If the grafted seedlings lose water and wilt, they can be remedied by spraying water in time with a watering can.
④ leaves. Used to cut off the growing points and heart leaves of rootstocks and cut rootstocks and scions. That is, the double-sided blade for general shaving is broken in half when grafting, which not only saves the blade, but also is convenient to operate.
⑤ Bamboo stick. In the insertion method, it is used to jack up the stems of rootstock seedlings and stir up the heart leaves and growing points of rootstock seedlings. Bamboo sticks are generally made of thin bamboo chips, with a length of 10 ~ 12 cm and a width of 0.3 ~ 0.5 cm. The jack end should be determined according to the thickness of rootstock, which is beneficial to the connection between scion and rootstock and ensures the survival rate of grafted seedlings.
6. Grafting clip. After grafting is completed, the joint of rootstock and scion should be fixed with special grafting clip. At present, there are two kinds of grafting clips on the market, one is a round grafting clip and the other is a square grafting clip. It should be noted that if the old grafting clip is used, it should be soaked in 200 times formaldehyde solution for 8 hours in advance for disinfection.
All landowners clear water. It must be kept clean during grafting, so clean hands and grafting equipment should be washed with clean water at any time.
8 disinfectant. Generally, the disinfectant used is 500 ~ 800 times that of 50% carbendazim or 75% chlorothalonil solution, which is used as the disinfectant for spraying grafted seedlings before and after grafting.
Pet-name ruby boards and benches. The function of the board is to build a grafting workbench, which is convenient for grafting operation and improves grafting speed.
(5) Factors affecting the survival of watermelon grafting.
① Compatibility between rootstock and scion. The affinity between rootstock and scion is reflected by affinity. Affinity refers to whether the rootstock and scion can survive after grafting and whether they can grow normally after survival. Therefore, the compatibility between rootstock and scion is not only the primary factor affecting the survival of grafting, but also the key to the normal growth of grafted seedlings after survival.
② Quality of rootstock and scion. In the process of grafting survival, cell division and callus formation need certain nutrients as the basis. If the rootstock and scion grow healthily and have sufficient nutrition, the callus will form rapidly and richly, which is beneficial to survival. Therefore, it is of great significance to cultivate age-appropriate rootstocks and scions with developed roots and strong stems and leaves to improve the survival rate of grafting.
③ Seedling age of rootstock and scion. The seedlings of rootstocks and scions are too tender, the tissues are too tender, the ability to provide nutrients and resist injury is weak, it is difficult to survive and the operation is inconvenient. If the rootstock and scion are too old, the degree of lignification of seedling stems is high, which is not conducive to the formation of callus. Especially for watermelon rootstock seedlings, the cavity in the center of the stem (called pith cavity) is formed when the seedling is a little older and increases with the increase of seedling age. When grafting, the incision is easy to reach the pith cavity, which makes it difficult to combine the scion and rootstock closely, and enables the scion to grow new roots along the pith cavity to reach the soil, so as to prevent soil-borne diseases through grafting. If it is a rootstock seedling with pith cavity, it is necessary to master the depth of incision when cutting. For older seedlings, the ratio of incision depth to stem diameter should be reduced accordingly to avoid cutting into pulp cavity. Therefore, the appropriate rootstock and scion age should be selected when grafting. In addition, according to different grafting methods, it is also important to cultivate seedlings suitable for rootstocks and scions. For example, the docking method requires that the size of rootstock and scion seedlings is equal or similar; When the high grafting method is adopted, it is required that the scion seedling age is small, the rootstock seedling age is 5 ~ 7 days, and the stem is roughly smaller than the rootstock.
④ Grafting technology. The tight combination of rootstock and scion section is the key to callus formation and the interconnection of rootstock and scion vascular bundle. Rootstock and scion can only be close to each other if their sections are flat and smooth. Therefore, when cutting, the blade should be sharp, and choose a blade with good quality to avoid repeated cutting. The incision depth should be appropriate, and the incision is too deep, which is easy to cut into the medullary cavity; The incision is too shallow, the contact surface between rootstock and scion is small and the healing area is small, which affects the survival rate. When fixing the contact surface between rootstock and scion, try to make the vascular bundle opposite. When fixing with grafting clips, pay attention to tightness. Too tight, easy to crush seedlings; Too loose, not easy to clamp, easy to cause scions to fall off.
⑤ Management technology after grafting. Besides the above factors, the survival rate of grafting is directly related to the management after grafting. The environmental conditions of grafting are very important, mainly referring to the temperature, humidity and illumination of the grafting site. Proper temperature is not only convenient for operation, but also beneficial to wound healing.
(6) Selection of seedbed and configuration of nutrient soil.
The seedbed should be located in the solar greenhouse with heating facilities, and the seedbed with low border which is beneficial to grafting should be selected, and the border surface in the seedbed must be flat to facilitate the placement of nutrition pots. The seedbed is generally 1.2 ~ 1.5 m wide and 5 ~ 6 m long, and its edge is about 20 cm below the ground or ridge. In winter and early spring, in order to improve the ground temperature and ensure the temperature, a ground hotline should be added, and a temperature controller should be added if possible to ensure the uniformity of seedling emergence at constant temperature.
The allocation of nutrient soil must meet the nutritional requirements of muskmelon rootstocks and scions, with superior cultivation conditions, loose, breathable, comprehensive nutrition, water and fertilizer conservation, and no pests and weeds. There are three ways to select its assignment.
(1) Select 50% peat and 50% fertile garden soil (the garden soil must be melons that have not been planted in recent years, and it is best to borrow soil from fields where crops such as onions, garlic and ginger have just been planted), and sieve the soil to remove impurities such as stones, weeds and sundries. Add ternary compound fertilizer 1 kg, 500 g urea and 50% carbendazim 100 g into each cubic meter of matrix, and mix well.
② Soilless seedling raising. According to the ratio of vermiculite to peat 1: 3 (by volume), in addition, ternary compound fertilizer 1 kg, 500g of urea, 50% carbendazim100g and appropriate trace elements are added to each cubic meter of substrate; Pay attention to the configuration to be fully mixed evenly and finely.
(3) According to the fully fermented high-quality organic fertilizer and garden soil without melon and vegetable planting, the ratio is 1: 1, in addition, ternary compound fertilizer 1 kg, urea 500 g, carbendazim 50% 100 g, and a small amount of trace elements, miaosu and bactericide are added to each cubic meter of substrate.
(7) Use the electric hotline to create a breeding ground.
Generally, there are 2 ~ 3 hotbeds for watermelon grafting and seedling raising, and each hotbed is independently controlled by a geothermal line, which is convenient for future temperature management. For rootstocks and scions of grafted watermelon seedlings, the power requirement of electric hotline is generally per square meter 100 watt. If possible, it is best to install a temperature control instrument and an electric hotline to facilitate temperature control.
The specific operation method is: it is best for three people to lay the hotline together. First, dig the seedbed. Generally, the seedbed is 5-6m long,1.2-1.5m wide and10cm deep. Be sure to flatten the bottom of the cup and step on it. Then prepare a small wooden stake inserted into the underground hotline, the length is about 15 cm. Step one, insert a small stake. The reasonable distance from common watermelon seedlings is 8 ~ 10 cm. Step two, pay off. One person at each end of the seedbed is responsible for hanging the line and the other person is responsible for paying off the line. Starting from one end, the heating wire must be kept on a horizontal plane, and the heating wire should be tightened and straightened when winding the stake. The number of wires must be even, so that the two wires can be on the same side and it is convenient to connect the power supply. Step 3, install the control gate and temperature controller. The fourth step is to scatter the soil and bury the thread. After the laying of the electric hotline is completed, the electric hotline should be covered with soil and buried, and it should not be exposed. The thickness of the soil is 5 cm, so it is better to flatten the border and prepare for seedling raising.
(8) Selection of seedling pots and pans and filling of nutrient soil.
Generally, only 8 cm× 8 cm or 9 cm× 9 cm is used for grafting watermelon rootstocks. The purpose of using nutrition bowl for rootstock seedling raising is to reduce the damage to root system during transplanting, which is beneficial to rapid seedling delay. As for the requirement of filling nutrient soil, since the rootstock seeds are directly planted in the nutrient bowl, it is best not to fill the nutrient soil too full, usually 7% ~ 80% full. The tightness of loading soil should be appropriate, too loose is not conducive to the growth of rootstocks, too tight is not conducive to ventilation, and it is easy to form water, so we must master the tightness of loading soil.
The scion seedling tray can be a flat-bottomed seedling tray, and the method of loading nutrient soil is basically the same as that of rootstock.
Rootstocks can also be cultivated in 72-hole trays. Put the cultivated peat and vermiculite nutrient soil into a 72-hole hole plate, and scrape it with a wooden board without compaction. After installation, water thoroughly with a watering can. Before sowing, use the same 72-hole tray, put it on the installed tray, and press it down from above by hand. The depth of this hole is about 1 cm. Then sow, cover with vermiculite, cover evenly, and put on the seedbed prepared in advance.
(9) Conditions of rootstock.
Rootstock should have the characteristics of resistance to diseases such as Fusarium wilt of melons, strong affinity with scion watermelons, high grafting survival rate, stable growth of grafted seedlings, normal fruits, no adverse effects on fruit quality, and convenient operation during grafting. The following aspects should be considered when selecting rootstocks.
① Disease resistance.
A. The main purpose of watermelon grafting is to prevent Fusarium wilt. Rootstocks not infected with watermelon Fusarium wilt were selected, and rootstocks of vegetable center breeding materials were screened in 1997, and two rootstocks with excellent comprehensive properties-Qianggang 1 and Qianggang No.2 were bred.
Xin Jing stock 1 was bred by 200 1.
B. fight against acute blight. Acute Fusarium wilt is a physiological disease, which occurs under the conditions of sudden rainfall, sunny day after heavy rain, high temperature, blocked root respiration and suffocation in the middle and late stage of results, resulting in root death. Without water absorption capacity, all the aboveground parts wilted and died within 1 ~ 2 days, and all crops were lost due to acute wilting. For example, in 1995, 3,000 mu of greenhouses in Sanhe County, Hebei Province failed due to acute wilt. Therefore, as a watermelon rootstock, the resistance to acute wilt must be considered.
2 affinity. According to some data, the genetic relationship between watermelon and other cucurbitaceae species is gourd, pumpkin, melon and cucumber in turn.
Affinity includes grafting affinity and raw affinity. Grafting affinity refers to the ability of rootstock and scion to heal; * * * Compatibility refers to the growth ability of scion and rootstock after grafting, including plant growth, flowering, fruiting and fruit development. * * * Grafted seedlings with strong affinity grow normally and grow more luxuriantly than self-rooted seedlings without grafting. If the affinity of * * * is weak, even if the grafting survives well, the later growth will be hindered, which is characterized by slow development, yellow seedlings and poor fruit setting.
Grafting affinity has a certain relationship with raw affinity, but they are not completely consistent. For example, some rootstock varieties have a high survival rate when grafted with watermelon, but after the plants enter the vine extension stage or fruit setting stage, the growth is blocked, the fruit setting is poor or the fruit cannot develop normally. However, the grafting survival rate of varieties with strong affinity is generally higher. Different grafting methods will also affect grafting affinity.
③ Fruit quality. As for the relationship between different rootstocks and watermelon fruit quality, it is generally believed that gourd rootstocks do not affect the sweetness, texture, color and flavor of fruits, while pumpkin rootstocks have poor fruit quality, which is mainly manifested in softening meat, worsening flavor, hollowness and increasing fiber.
Watermelon grafted with pumpkin affects flavor and appears hollow. The fiber content, skin thickness and sugar content of different rootstocks are different after grafting, which affects the quality.
(10) Determination of watermelon grafting method.
The grafting method of melon vegetables is mainly determined by the purpose of grafting, the types of rootstocks and scions, and the proficiency of grafting operators in mastering technology.
① Determine the grafting method according to the grafting purpose. For the purpose of disease prevention, attention should be paid to keeping the grafting site away from the ground to avoid pollution caused by adventitious roots or contact with soil at the interface. The selected grafting methods are splicing and pasting. If the purpose is non-disease prevention, grafting methods with high survival rate and easy management after grafting, such as grafting, can be selected according to the situation of rootstocks and scions.
② Determine the grafting method according to the variety types of rootstock and scion. If the scion seedling is small and the hypocotyl is thin, the insertion method should be adopted; If the scion seedling is large and the hypocotyl thickness is similar to that of the rootstock, the docking method is adopted; When the stems of rootstock seedlings are prone to cavity, grafting method should be adopted.
③ Determine the grafting method according to the skill of the grafting operator. If the grafting operator is skilled in grafting technology and the management level of grafted seedlings is high, methods with better grafting effect should be selected, such as insertion method and attachment method. If the grafting operator is not familiar with grafting technology and has no experience in grafting seedling management, then the grafting method with high survival rate of grafted seedlings should be chosen.
(1 1) Problems needing attention in soaking watermelon rootstocks and scions to accelerate germination.
(1) When using warm soaking method, to ensure the temperature of water, scald the seeds in hot water at 60 ~ 65℃ for 15 minutes, and then keep one-way stirring until the temperature drops to 30℃ for soaking. If you are not sure about the temperature, be sure to use a thermometer to test it, and replenish hot water in time when the water temperature is not enough.
(2) When soaking seeds with chemicals, the seeds must be soaked with clear water for 4-6 hours before soaking, and then soaked with chemicals. After being removed from the liquid medicine, the seeds must be washed with clear water and then germinated.
(3) When soaking seeds with chemicals, the soaking time and the concentration of liquid medicine should be strictly controlled. The time is too short or the concentration of liquid medicine is not enough to achieve the purpose of sterilization; On the contrary, if the time is too short or the liquid medicine is too high, the germination rate of seeds will be reduced.
(4) In the process of accelerating germination, the seeds must be turned frequently, and the seeds must be washed with warm water every day before germination to supplement oxygen. Good ventilation environment is conducive to seed germination.
(12) Grafting methods commonly used in watermelon and their characteristics.
At present, there are four main grafting methods of melon: docking method, inserting method, splitting method and sticking method.
① Plug-in method. Insertion method is to insert a bamboo stick into the top of the seedling stem of the rootstock and insert the cut scion into the hole. The grafting process is divided into four links, namely, the rootstock seedling is cored and inserted, the scion is cut and the scion is inserted into the rootstock. The main features are: a. Good disease prevention effect. The scion is far from the ground, which is not easy to cause soil pollution, so the disease control effect is the most obvious. B. the grafting speed is fast. The grafting method has few working procedures and saves working hours, so the grafting speed is fast. C. Grafting rootstock scions have high requirements and must be suitable for grafting.