Detailed Explanation of Key Technical Points for Potato Sprout Planting

In order to prevent potato degeneration, prevent ring rot, and solve the problem of insufficient supply of improved seeds, we conducted a sprout planting experiment from 2000-2002 using the potato variety Longshu No. 3. The results were: light field disease, a yield of 3600 kg/mu, large and uniform tubers, and a high marketable rate. The cultivation techniques are introduced as follows:

(1) Raising seedlings

1. Selecting land and making beds. Choose a plot with flat terrain, loose soil, and convenient water source as the seedling-raising site. The seedbed width is 1.2 m, and the length is determined according to the planting area. Dig out the topsoil from the seedling-raising site, use subsoil to build the ridges, first add topsoil, then add a 10 cm thick layer of horse manure and a 5 cm thick layer of nutrient soil (prepared at a ratio of high-quality farmyard manure:garden soil = 1:5), making a 30 cm deep heated seedbed.

2. Sowing and management. In late April, select seed potatoes with uniform tuber shape, consistent size, and plump eyes, place them with the eyes facing upward, arrange them neatly to fill the seedbed, cover with nutrient soil (same as above) 3-4 cm thick, water thoroughly, and spray-disinfect with a 50% carbendazim wettable powder 800-fold solution.

During the seedling-raising period, the soil should be kept moist, and water should be applied whenever it dries. The temperature should be maintained at 10-20°C. If the temperature is too low, a small arched shed can be made on the bed surface to keep warm, so as to ensure seedling emergence.

(2) Field transplanting

1. Land preparation and film mulching. Deeply plow the soil 20 cm, apply organic fertilizer 3000-5000 kg/mu and ordinary superphosphate 20 kg/mu as base fertilizer. Remove weeds, stones, and other debris. Make ridges with a bottom width of 120 cm, a surface width of 110 cm, and a height of 10 cm, with a ridge spacing of 40-50 cm. To save water, leave a hidden irrigation ditch 10 cm deep and 10 cm wide in the middle of the ridge surface, so that under-film hidden irrigation can be carried out during drought. Before ridging, the soil should have good moisture. If the bottom moisture is insufficient, water thoroughly first, and cover with film immediately after ridging.

2. Transplanting. About 10 days after sowing, when the seedlings grow to 6-10 cm long and have 5-7 leaves, dig out the tubers, break off the seedlings together with the fibrous roots, and transplant them onto the previously made ridges, planting 2 rows per ridge with a plant spacing of 30 cm. When planting seedlings, first use a hole puncher to make holes 6-8 cm deep on the ridge, plant 1-2 seedlings per hole, then fill with wet soil and press the holes firmly to facilitate heat preservation and moisture retention. Return the seed potatoes after sprout removal to the original place to continue raising seedlings; sprouts can be removed 3-4 times.

(3) Field management

1. Water management. After potatoes are planted in the field, there must be good moisture during the seedling recovery period. If necessary, holes can be opened in the film at both ends of the hidden irrigation ditch to inject water until the hidden irrigation ditch is full, and the holes should be sealed promptly after irrigation.

2. Topdressing. During the rosette stage of potatoes, apply urea 8-10 kg/mu and potassium sulfate 20 kg/mu as a one-time topdressing. When using hole application, make holes 10 cm away from the plants and apply, or inject with a fertilizer gun; when using furrow application, open a furrow 10 cm away from the plant rows and broadcast, then cover with soil after irrigation.

3. Cultivation and weeding. Carry out cultivation in a timely manner and remove weeds between rows in the field to help preserve soil moisture. Combined with cultivation, earth up the plants to increase yield per plant.

4. Pest and disease control. During the growth period of sprout-planted potatoes, prevention work for pests and diseases should be done well. Once pests or diseases occur, measures should be taken immediately to achieve "early treatment and treatment while small." A common disease is potato late blight. When central diseased plants appear, spray around them with a 70% thiophanate-methyl wettable powder 800-1000-fold solution for control.

(4) Precautions. First, strictly select seed potatoes according to requirements; the seed potatoes are required to be pure in variety, smooth in surface, and free of pests and diseases. Second, seed potatoes used for sprout-planted seedling raising can produce 2-4 sprouts each time and can have sprouts removed continuously 3-4 times, so the utilization rate of seed potatoes is very high. After each sprout removal, promptly return them to the seedbed for another round of seedling raising. Third, the seedling raising period in the seedbed is usually 3-5 days earlier than direct sowing, so the seedling raising time should be determined according to the planting period and the number of days required for seedling raising, to prevent too-early planting from being attacked by late frost.