Spring Asparagus Planting: Seedling Raising Methods and Key Technical Points
How do you raise seedlings for spring asparagus planting? Please advise. Asparagus production generally adopts seedling raising and transplanting. Centralized seedling raising and transplanting gives a high emergence rate, can save seeds, lower costs, facilitates centralized management, helps prevent and control pests and diseases and cultivate strong seedlings; it can extend the growing period in the planting year and increase the yield in the second year; when transplanting, the seedlings can be...
How do you raise seedlings for spring asparagus planting? Please advise.
Asparagus production generally adopts seedling raising and transplanting. Centralized seedling raising and transplanting gives a high emergence rate, can save seeds, lower costs, facilitates centralized management, helps prevent and control pests and diseases and cultivate strong seedlings; it can extend the growing period in the planting year and increase the yield in the second year; when transplanting, the seedlings can be oriented and planted according to the growth direction of asparagus, which facilitates ridging, spear harvesting and management operations.
1. Cultivation season and sowing period
Asparagus is mostly sown in spring, but can also be sown in autumn. Spring sowing is generally done from February to April, with planting from April to June, and spear harvesting begins in the spring of the second year; autumn sowing is done from August to September, with planting from October to November, and spears can be harvested in the autumn of the second year. The sowing period can be set 60 to 80 days before the planting date, depending on the previous crop and seedling raising conditions.
2. Selection of the seedling raising site and preparation of the seedbed
The seedling raising site should be loam or sandy loam with loose soil, fertile soil and good aeration, with conditions for irrigation and drainage, and an open, well-ventilated environment. Since asparagus and allium vegetables are both crops of the Liliaceae family, in order to reduce the occurrence of pests and diseases, plots whose previous crop was allium vegetables are not suitable as a seedling raising or cultivation site for asparagus.
3. Seedling raising methods and seedbed preparation
The main seedling raising methods include solar greenhouse seedling raising, plastic low-tunnel seedling raising, cold-frame seedling raising and open-field seedling raising. The use of nutrient pots for seedling raising is advocated, as it causes less root damage at transplanting and gives a high survival rate.
1. Solar greenhouse seedling raising: Nutrient pots can be used for seedling raising. The nutrient pots should be prepared before sowing, and the diameter of the nutrient pots is generally 8 to 10 cm. The nutrient soil is prepared with 30% garden soil, 35% barnyard manure, 30% peat soil, 1.5% compound fertilizer, 0.5% urea, 1% phosphate fertilizer and 20% potassium chloride, then sieved, put into pots and placed in the bed. Before placing them, use 4 to 5 kg of phoxim per mu of seedbed, add an appropriate amount of sandy soil to make medicated soil and spread it on the seedbed to prevent underground pests. Cover with film and straw mats 10 to 15 days before sowing to raise the temperature.
2. Low-tunnel or cold-frame seedling raising: The cold frame can be made before winter, generally made into a south-facing cold frame 1.5 m wide and 10 to 15 m long, with the north wall 10 cm higher than the south wall. Nutrient pots can be used for seedling raising, and the preparation method of the nutrient pots is the same as for the solar greenhouse. The prepared nutrient pots are placed in the cold frame or low tunnel.
3. Open-field seedling raising: Apply 3000 to 5000 kg of decomposed compost and 50 kg of Sakefu compound fertilizer per mu, spread evenly and plow 25 cm deep, then make beds after fine soil preparation, making beds 1.2 to 1.5 m wide, and level the bed surface so that the soil is fine and crumbly and the bed surface is flat. For planting white asparagus, use 60 to 70 g of seed per mu, occupying 20 to 30 sq m of seedling land; for planting green asparagus, use 90 to 100 g of seed per mu, occupying 30 to 40 sq m of seedling land.
4. Seed soaking and sprouting
Asparagus seeds have a thick, hard coat and strong cutinization, absorb water with difficulty and germinate slowly. To promote asparagus seed germination, the seeds must be sprouted before sowing. Before sowing, the seeds can first be dried in the sun for 1 to 2 days, then the shriveled seeds and insect-damaged seeds are floated off with clean water, soaked for 10 to 12 hours in a 300-fold dilution of 50% carbendazim, then soaked for 2 days in warm water at 30°C to 35°C, changing the water 1 to 2 times a day. Once the seeds have absorbed enough water, take them out, put them in a basin, cover them well with wet gauze or a towel, or wrap them well with wet gauze or a towel, and place them at 25°C to 30°C to sprout, rinsing with tap water 2 to 3 times a day, and sow promptly after germination.
5. Sowing
Before sowing, water the nutrient pot seedling bed or open-field seedbed thoroughly, and after the water seeps in, spread a thin layer of soil. On the open-field seedbed, draw lines at a spacing of 10 cm between plants and rows, or cut soil blocks 10 cm square with a knife, take one germinated seed and sow it in the center of the square or the center of the nutrient pot, cover with medicated soil 2 to 3 cm deep, and cover with film after sowing. In the open field, broadcast sowing or furrow drilling can also be used.
6. Seedbed management
1. Temperature: The suitable temperature for asparagus germination is 25°C to 28°C. For low-tunnel or cold-frame seedling raising, the daytime temperature should be controlled at 25°C to 28°C and the nighttime temperature at 15°C to 18°C. After emergence, keep it at 25°C during the day, with the lowest temperature not below 8°C and the highest not above 30°C; ventilate promptly when it exceeds 30°C. Gradually increase ventilation to harden the seedlings so they adapt to the external natural environment. When the seedlings have more than 3 aboveground stems, they can be transplanted.
2. Water and fertilizer: Before emergence, the seedbed soil should be kept moist; otherwise, water promptly. After emergence, the seedling root system is weak, so water promptly when dry. When the seedlings are about 10 cm tall, apply a thin organic liquid fertilizer with the water once, such as fully decomposed human manure and urine or biogas slurry, or apply urea and potassium chloride, etc. with the water. Topdress 2 to 3 times during the seedling stage, so that the seedlings can fully accumulate assimilated nutrients in the later growth stage and be cultivated into strong seedlings.
3. Intertillage and weeding: After emergence, remove the plastic film immediately. For broadcast sowing, thin the seedlings after full emergence, keeping a spacing of 7 to 10 cm. During the seedling raising period, weed frequently and loosen the soil with timely intertillage. Hill up appropriately so that the scale buds develop thick and strong and the seedlings are prevented from lodging. When the seedlings meet the standards for transplanting, they can be transplanted. The transplanting standards are: seedling height about 0.3 m, with more than 3 aboveground stems and more than 5 underground storage roots.
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