Comprehensive information on seedling raising

Yùmiáo means cultivating seedlings. The original meaning is to cultivate seedlings in nurseries, hotbeds or greenhouses in preparation for transplanting to the ground for planting. It can also refer to the stage when various organisms are artificially protected until they can survive independently. As the saying goes, "The growth of the seedlings is half the harvest." Seedling cultivation is a labor-intensive, time-consuming, and highly technical task. Basic introduction Chinese name: Seedling Pinyin: yùmiáo Definition: Characteristics of cultivating seedlings: labor-intensive, time-consuming, and highly technical Basic information, seedling facilities, sowing, selection of plug trays, substrate selection and filling, drilling and sowing, uniform coverage, Daily management, water management, fertilizers and nutrients, pest and disease control, plant type control, basic information. Zhengzhou Zhonglian Chemical's technical staff found through research that in the past, most of the seedlings used traditional open-field direct seeding or used Yang Qi, improved Yang Qi and solar greenhouse seedlings. Due to poor equipment and the influence of natural conditions, seedlings are long-lived, of poor quality, of varying sizes, and costly. Natural disasters such as freezing damage or pests and diseases often cause a shortage of seedlings. Furthermore, traditional seedling breeding technology only relies on experience, and there are many technical errors. In particular, it is difficult to master and promote seedlings based on experience alone. For this reason, we recommend the centralized seedling transplanting method, which has many benefits, such as: 1. Convenient management in the early stage of centralized seedling cultivation, especially pest control; 2. The seedlings will not be slowed down after planting and the plants will grow neatly; 3. The substrate used for seedling cultivation The nutritional formula is reasonable, the cultivated seedlings are strong, have well-developed root systems, grow quickly, have good flower bud differentiation, increase yields and can be marketed earlier; 4. The special substrate for seedlings is used to be pathogen-free and non-toxic, which reduces the occurrence of soil-borne diseases; 5. Plastic tray seedlings Easy to transport, saving effort, time and labor. Seedling facilities 1. Selection of nursery sites. The nursery sites should be located in a place with convenient transportation, flat, open land, no accumulation of water, and a water source and power supply. The environmental conditions of the nursery sites must meet the requirements for pollution-free production. At the same time, it meets the needs of building nursery sheds and other facilities according to the scale of nursery. 2. Basic facilities: The nursery shed adopts a standard steel frame greenhouse, which is generally 6m wide, 1.8m high and 20m long. If economic conditions do not allow it, a bamboo frame greenhouse can also be used. The size of the nursery shed can be adjusted according to the scale of the nursery. The plastic film and sunshade net covering the seedling shed should be selected according to the weather conditions and the needs of the seedling raising process. Greenhouse covering materials mainly include films, sunshade nets, insect-proof nets, etc. 3. Selection of seedling plug trays: Choose 72 holes for peppers, tomatoes, and eggplants, 54×28cm soft disks, each hole has a diameter of 3.8cm at the top, 2.0cm at the bottom, and a hole depth of 4.6cm. Bitter melon, pumpkin, green (yellow) melon, melon, and winter melon: Select 50 holes, 54×28cm floppy disk, each hole has a top diameter of 5 cm, a bottom diameter of 2.2 cm, and a depth of 5 cm. In addition, used plug trays may be infected with residual pathogenic bacteria and insect eggs, so they must be cleaned and disinfected. The method is to first remove the residual matrix in the seedling tray, rinse it with clean water, dry it, and soak it in 500 times carbendazim solution for 12 hours or 1000 times potassium permanganate solution for 30 minutes for disinfection. Formaldehyde solution and bleaching powder solution can also be used. Carry out disinfection. Sterilized plug trays must be thoroughly washed with water and dried before use. 4. Preparation of seedling substrate. The seedling substrate uses high-temperature retting coconut bran: disinfected topsoil (fields that have not been planted with melons and vegetables for 2-3 years): organic fertilizer (organic fertilizer must use products that meet the specifications of the industry standard NY525. The organic matter content is not less than 30% or the chicken manure, cow manure, and pig manure after high-temperature retting) are mixed thoroughly in a volume ratio of 70:27:3. Put the substrate into the rootstock seedling plug tray, spray the plug tray with Julixing activated rooting dispersant or spray the seedling plug tray with 50% carbendazim 600-800 times solution, and water the seedling substrate thoroughly. You can also choose to purchase special substrate for seedlings. The price of seedling substrate is about 1 yuan/plant for melons, 0.7 yuan/plant for peppers, tomatoes, and eggplants. 5. Seedbed setting: When raising seedlings in a standard steel frame greenhouse, two seedbeds can be set up on the left and right, with an operating lane left in the middle. The specifications of the seedbed are: the width of the seedbed is 2m, each bed has 6 rows of seedling trays arranged vertically, the operating channel between the two beds is 0.6m wide, and the distance between the edge of the bed and both sides of the greenhouse is 0.7m. The length of the seedbed depends on the specific conditions of the greenhouse. Multi-span greenhouses can arrange seedling trays according to the above method. When raising seedlings, lay an undamaged film on the surface of the seedbed to retain moisture and prevent seedling roots and excess water and nutrient solution from seeping into the ground. According to the above settings of the seedbed, about 2,600 floppy disks can be placed in the seedling shed per acre (667㎡). The seedling cultivation time is about one month. One emergence of seedlings in the nursery can provide 50 to 80 acres of peppers, about 100 tomatoes, 80 to 100 acres of eggplants; 80 to 100 acres of melons, 40 to 50 acres of cucumbers, 200 acres of winter melons, pumpkins, There are about 220 to 250 acres of bitter melon. 6. Setting of nutrient solution pool Fertilization is in the form of spraying. The construction of nutrient solution pool can be adapted to local conditions and according to specific conditions. The volume is configured according to the standard of spraying 1--1.5kg/㎡ on the seedbed area. Sowing: Choose an appropriate plug tray, select a good substrate, fill the substrate correctly, drill a hole, sow the seeds evenly into the center of the hole, cover the seeds evenly, and water appropriately. This completes the first step of factory-based plug seedling cultivation.

Selection of plug trays: The smaller the plug tray, the more sensitive the plug seedlings will be to changes in moisture, nutrients, oxygen, PH value, and EC value in the soil. The deeper the hole, the more air there is in the matrix, which is conducive to ventilation, salt elution and ventilation, and is conducive to the growth of the root system. The depth of the matrix must be at least 5mm to have the effect of gravity, allowing the moisture in the matrix to seep down. The deeper the air enters the hole, the more oxygen it contains. The shape of the hole should be a square inverted trapezoid, which will help guide the roots to extend downward, instead of the roots wrapping around the inner wall like in holes with round or vertical sides. Deeper holes provide more favorable conditions for drainage and ventilation of the matrix. Some plug trays also have ventilation holes between the holes so that air can flow between the plants. Keep the leaves dry, reduce diseases, dry evenly, and ensure uniform growth of the entire plant. The color of the plug tray also affects the temperature of the plant roots. Generally, black plug trays are chosen in winter and spring because they can absorb more solar energy and increase the root temperature. In summer or early autumn, it is necessary to change to silver-gray plug trays to reflect more light and avoid excessive root temperature. White plug trays generally have higher light transmittance, which will affect root growth, so white plug trays are rarely chosen. Of course, white foam trays are an exception. Thoroughly cleaned and disinfected plug trays can also be reused. It is recommended to use safer quaternary ammonium salt disinfectants, which can also be used for sterilization and algae removal in irrigation systems to avoid the growth of bacteria and moss. It is not recommended to use bleach or chlorine for disinfection because chlorine will chemically react with the plastic in the tray to produce toxic substances. Matrix selection and filling matrix selection: A good matrix should have the following characteristics: ideal water capacity; good drainage and air capacity; easy rewetting; good porosity and uniform void distribution; stable vascular bundle structure , less dust; appropriate pH value, 5.5-6.5; contains appropriate nutrients to ensure the nutrient requirements before the cotyledons expand; extremely low salt level, EC should be less than 0.7 (1:2 dilution method); the size of the matrix particles is uniform Consistent; free of plant diseases, insect pests and weeds; consistent quality from batch to batch of substrate. Because the role of vermiculite with smaller particles is to increase the water retention capacity of the matrix rather than the porosity. To increase the drainage and breathability of your peat substrate, choose to add perlite instead of vermiculite. On the contrary, if you want to increase the water holding capacity, you can add a certain amount of small particles of vermiculite.

Pay attention to the following points: Although imported peat is an ideal source of raw material for seedling cultivation substrates, due to its high price and non-renewable resources, Western countries have gradually switched to processed coconut shell crushing as the substrate. Source, the effect is just as good. They call it coconut peat. 1. The matrix should be fully moistened before filling, generally 60% is appropriate. Hold a handful of the matrix with your hand. If no water is squeezed out, it will form a ball when you release your hand, but if you touch it lightly, the matrix will spread out. If it is too dry, the substrate will collapse after future watering, resulting in poor ventilation and poor root development. 2. The filling degree of each hole must be uniform, otherwise holes with less matrix will dry faster, resulting in uneven water management; 3. The matrix of holes for sowing large seeds such as melons should not be too full; 4. Avoid squeezing the substrate, otherwise it will affect the air permeability and drying speed of the substrate, and because the substrate is pressed too tightly, the seeds will rebound, resulting in different shades of seeds when they finally germinate. Drilling holes and sowing seeds Note: The depth of drilling holes should be consistent to ensure that the depth of sowing seeds is also consistent. Generally, the larger the seeds, the deeper they can be sown. Evenly covering several common vegetable seeds require dark conditions to germinate smoothly, so it is also important to choose appropriate covering. There are several aspects to consider when choosing a covering: it can increase the humidity around the seeds and maintain good air permeability to provide sufficient oxygen to the seeds. It is recommended to use large grain vermiculite as mulch. Perlite coverings tend to breed moss. 5. Initial watering after sowing: Two options: When the seeds germinate on the seedbed, pour a small amount of water first. After all the plug trays are moved to the seedbed, water them again and again. If the seeds are in a germination room or a simple germination space (after being covered with grass thatch to retain moisture), they must be thoroughly watered before entering the germination room. It is recommended to use an atomizing nozzle or a nozzle with fine water spray. Daily management After the sowing work is completed, the daily management stage begins. It will be elaborated from four aspects: watering, fertilizing, pest and disease control and plant type control. Water Management The most important task in the seedling production process is water management. But in the actual work process, it is often done by people with little experience. Watering at inappropriate times or in the wrong way will seriously affect the production of plug seedlings. Never allow plug seedlings to completely dry; conversely, it will not work if the water in the matrix is ​​too saturated, which will cause root hypoxia (0-2%). Water management for plug seedling production generally takes the expansion of the cotyledons as the dividing line. Water management before the cotyledons unfold is relatively simple, that is, the lower half of the hole matrix must be kept moist at all times. Just control the alternation of dryness and wetness of the matrix in the upper half of the hole. After the cotyledons expand, the lower half of the hole substrate must be controlled to be dry or wet according to environmental changes and plant growth. You can dig up part of the substrate before watering and observe whether there is a certain amount of moisture in the lower part. Of course, it is an ideal testing method to hold up the plug tray and estimate its weight to judge the humidity of the substrate. The prerequisite is that you must have some experience to know the weight of the plug tray at different humidity levels.

You can also lift the plug tray to see if the substrate at the bottom of the plug tray has dried out to determine whether to replenish water. By watering, let 10% of the water seep out of the plug tray to enter the wet cycle. When fertilizing or applying pesticides, they must be watered thoroughly. When pouring water, just pour it until the water flows through the plug tray. Water in the matrix is ​​lost through evaporation and water absorption by the roots. The former plays a major role before the cotyledons expand; while after the cotyledons expand, the root's water absorption, which is dominated by transpiration, plays a major role. So at this time we have to judge how to water based on the impact of changes in environmental climate on plant transpiration. For example, in the following situations, it is more appropriate for the water to only reach half of the hole: 1. The weather changes from sunny to cloudy or cold, or the humidity in the greenhouse is extremely high. The water evaporates slowly, the transpiration is low, and the plug tray is not easy to dry out. 2. There is still a certain humidity in the lower part of the hole. 3. The seedlings need to be fertilized the next day. When the weather is hot, seedling growers can effectively control the seedlings by using the technique of half water flow. If watered too often, the plants will easily grow leggy, reduce the air permeability of the substrate, cause damage to the root system, and become susceptible to bacterial infection. Watering the greenhouse is the most important task and should not be performed by an inexperienced person. Watering requires more experience accumulated by workers on their own initiative rather than written or oral knowledge. A few notes on water quality: pH, alkalinity and EC. The pH value of production water should be in the range of 5.0-6.5, because most nutrients and pesticides are effective within this range, and the effectiveness beyond this range will be greatly reduced. The alkalinity of water represents its buffering capacity. If the alkalinity is too low, the pH value of the substrate will fluctuate widely with the pH of the fertilizer. This may lead to a lack of certain trace elements or poisoning. If the alkalinity is too high, it may also easily lead to a lack of certain trace elements, such as iron, boron, etc. EC value. Generally, the EC value of irrigation water without fertilizers must be lower than 1.0ms/cm to be suitable for production. High concentrations of soluble salts can reduce germination rates, damage roots and root hairs, and burn leaves. Do not let the substrate in the plug tray get too dry, otherwise the salt concentration around the roots will increase by 3-4 times. Generally, for soft water with very low calcium and magnesium content, the alkalinity is very low, so it is necessary to use an alkaline fertilizer containing calcium and magnesium, which can increase its buffering capacity. If the alkalinity is high, there is no need to use this type of fertilizer, and attention should be paid to adjusting it with acidic fertilizers. Special attention should be paid to the fact that in some areas in the north, when the summer rainy season comes, the hardness, pH value and EC value of groundwater will be significantly higher than usual, which can easily reduce the utilization rate of phosphate fertilizers and lead to iron deficiency and other trace element deficiencies. Especially when using manganese-containing broad-spectrum fungicides such as mancozeb, you must pay more attention to the occurrence and prevention of iron deficiency. Because iron is most likely to compete with manganese, when the substrate is humid and the temperature is below 15°C, and the pH value is higher than 6.5, iron will not be effectively absorbed by the roots. Fertilizers and Nutrients Selection of seedling fertilizers Generally speaking, a good commercial seedling medium can provide all the nutrients needed until the cotyledons are fully expanded. Because the plug container is small and rinses quickly, the pH value of the substrate changes quickly, and salt easily accumulates and damages the root system of the seedlings. Therefore, we must choose high-quality and stable water-soluble fertilizer as a nutrient supplement after the cotyledons are fully expanded. When choosing fertilizers, two factors should be considered: 1. The composition of nitrogen in the fertilizer itself: There are three types of nitrogen, which have different effects on plant growth. 2. Choose different fertilizer formulas depending on the regional environmental conditions and climate.

The adverse effects of high humidity on seedlings are as follows: internodes are too long, stem segments are too thin, branches are few, and roots are produced. At the same time, the absorption of calcium by the roots will be reduced under high humidity conditions, because of the impact of environmental humidity on vegetable seedlings: high humidity and poor ventilation can easily induce diseases. On the other hand, if the ambient humidity is too low, the transpiration of the plant will be too strong in an environment of high temperature and strong light. The water absorbed by the plant through the roots will not be enough to replenish the water lost by the leaves, and the stomata will close to protect the plant from losing water. excessive. Since the stomata are closed, carbon dioxide is also prevented from entering the plant, so photosynthesis will also stop and the plant will stop growing. Under low humidity conditions, the transpiration of plug seedlings is accelerated, which promotes the plant's absorption of calcium and magnesium. In the absence of water, the stomata will close. Growth is stopped, so low humidity results in stronger stems, greater resistance to stress, and better root development. Therefore, it is necessary to prevent the symptoms of calcium and magnesium deficiency on continuous cloudy days, and use leaves to supplement them in time. The normal leaf color should be pure green. If the lower leaves turn yellow, it means that the plant has insufficient nutrients or the root system is injured. Dark green leaves indicate too much ammonium fertilizer. Light green leaves indicate nitrogen deficiency, ammonium toxicity or magnesium deficiency. Pest and disease control: Plug seedlings last for a short period of time, so they are rarely threatened by pests and diseases. However, because they grow too densely and in large numbers, if the environment is poorly controlled or managed improperly, there will also be problems with pests and diseases. Plant type control For commercial seedling producers, neat and stocky plug seedlings are the common goal. Many breeders have put in a lot of effort into this. The most common method is to manually transplant the seedlings once in the middle stage of the seedling cultivation to solve the problem of neat transplantation. If you refer to our suggestions in previous work (choose seeds and substrates with high consistency, fill them correctly, drill holes evenly and sow seeds evenly, water them evenly), then the labor of this work can be greatly reduced.

In order to achieve short and sturdy seedlings, many seedling growers will choose to use chemical growth regulators to control the height of the plants in production practice. We would like to remind you that this is a more efficient but also more dangerous approach. First of all, we do not agree with the use of chemical hormones in food. The use of hormones again has many side effects, and there are certain requirements on the usage method and environmental conditions. For example, chlormequat can only slowly enter the leaves when the leaves are wet, so it is best to use it in the evening. Be sure not to use hormones when plants are short of water, otherwise they may cause phytotoxicity. Here are several ways to control plant height other than hormones: 1. Negative day-night temperature difference (nighttime temperature is 3-6 degrees higher than daytime temperature for more than 3 hours) is very effective in controlling plant height. The production method is to reduce the daytime temperature as much as possible. The temperature three or four hours before and after exposure. 2. Lowering the temperature, moisture or relative humidity of the environment, using nitrate nitrogen fertilizers to replace ammonium nitrogen fertilizers and urea fertilizers, or overall reducing the amount of fertilizer used, increasing light and other methods can inhibit the growth of plants. 3. There are also some mechanical methods such as stirring, vibration and increasing air flow, which can inhibit the growth of plants. For example, if you shake a tomato plant several times a day, the height of the plant can be significantly reduced. In this way, care must be taken to avoid damaging the leaves. This is not suitable for crops such as peppers whose leaves are easily injured. Of course, if you use hormones, especially chlormequat, excessively, drug harm will occur. In addition to spraying hormones with opposite effects to relieve the effect of the drug, and appropriately increasing water and ammonium nitrogen to promote growth, you can try foliar spraying of seaweed essence, which will achieve obvious results. If the roots located on the outside of the substrate and at the bottom of the plug are long and slender, they are often called water roots, which indicates excessive watering and the substrate is not breathable. Even if root hairs are produced, they will be lost when encountering high salt and drought conditions. The loss of root hairs will prevent the growth of seedlings, prolong the seedling slowing period after transplanting, and easily cause root rot due to bacterial infection.