High-Yield Spring Cultivation Techniques for Potatoes in Double-Cropping Regions

I. Select High-Quality Virus-Free Seed Potatoes

In double-cropping regions, the spring period suitable for potato growth is relatively short (60-70 days), so it is essential to select early-maturing virus-free varieties with a short dormancy period, early tuber formation, rapid tuber expansion, strong stress resistance, and high quality and yield, such as Yupotato No. 1 and No. 2, and Favorita. The seeding rate is 120 kg per mu.

II. Early Cutting and Early Sprouting

1. Warm the seed potatoes and cut them. Before cutting, place the seed potatoes in a room or a sun-heated cold frame at 12-15°C for 5-7 days to warm them, prompting the seed potatoes to break dormancy and the eyes to sprout. About 25 days before sowing, cut the seed potatoes. Use the equal-division cutting method: for tubers under 25 g, simply cut off the navel end to stimulate sprouting; for tubers of 25-50 g, cut lengthwise into 2 pieces, using the terminal bud for strong growth vigor; for tubers of 80-100 g, cut vertically from top to bottom into 4 pieces; for larger tubers, start cutting from the navel end, cut to the middle-upper part, then make a cross-shaped vertical cut; large tubers can also first be cut vertically into two halves, then each half cut sequentially from the navel-end eyes. Requirements: each kilogram of seed potatoes should yield about 45 pieces, with uniform size; each piece should preferably be triangular with thick flesh; each piece should retain at least one eye, and the cut should be as close to the eye as possible; for large tubers, one eye can be divided into two sprouting pieces. The cutting knife should be sharp, thin, and clean. When a diseased or rotten tuber is encountered, sterilize the knife by soaking in a 5% potassium permanganate solution for 1-2 minutes. After cutting, spread the seed pieces in a sheltered, sunny place to dry the cut surfaces and promote wound healing.

2. Sprouting treatment. After the wounds heal, carry out sprouting. ① Indoor sprouting. Place the dried seed pieces in a basket, cover with moist burlap, and maintain at 15-18°C. ② Outdoor sprouting. Choose a sheltered, sunny spot to build a sun-heated cold frame for sprouting. The frame should be 1 m wide, with length depending on the amount of seed. Spread a 5 cm layer of wet sand inside, place a layer of seed pieces, sprinkle a layer of wet sand, place a layer of seed potatoes, then sprinkle another layer of wet sand. In this way, 2 layers of seed potatoes can be placed. Do not pile too thickly to prevent rot. Cover with straw mats at night, uncover at 8 AM, and cover again at 5 PM to ensure sufficient light. The temperature inside the frame should be maintained at 15-18°C.

III. Scientific Fertilization for High Yield

Choose flat terrain with convenient irrigation and drainage and fertile sandy loam soil for planting potatoes, and avoid continuous cropping with Solanaceae crops. Adopt a balanced fertilization method of "mainly organic fertilizer, combined with nitrogen, phosphorus, potassium, and micronutrients." For a field with a target yield of 2500-3000 kg per mu, the fertilization standard is: apply 5 cubic meters of high-quality barnyard manure per mu, 50-75 kg of potato-specific compound fertilizer or 25-30 kg each of diammonium phosphate, urea, and potassium sulfate, 1 kg of zinc sulfate, and 0.5 kg of borax. Apply farmyard manure in combination with plowing and land preparation; apply chemical fertilizers as seed fertilizer or topdressing, applied in bands at sowing. When using plastic film mulching cultivation, apply all fertilizers as base fertilizer at once; for open-field cultivation, reserve 25 kg of compound fertilizer or 40-50 kg of ammonium bicarbonate for topdressing when about 80% of seedlings have emerged, and apply the remaining fertilizers as base fertilizer at once, with a tillage depth of about 30 cm.

IV. Scientific Sowing for High Yield

1. Sow as early as appropriate. In double-cropping regions, the effective spring growing period suitable for potatoes is only 60-70 days, so sowing must be done as early as possible to achieve high quality, high yield, and high efficiency. The general requirement: begin sowing when the soil temperature at a depth of 10 cm reaches 7-15°C. Adjust the sowing time according to local climate conditions and sow as early as possible.

2. Sow deep with sufficient soil moisture. If the base soil moisture is insufficient, water first, then prepare the land, and then sow to ensure full emergence. In early spring, soil temperature is low and the air is dry. If protected cultivation is used, hilling is not easy, so deep sowing is necessary. The sowing depth for Yupotato No. 1 and No. 2 is 10 cm, and for Favorita it is 12-15 cm.

3. Sowing density and cultivation mode. For early-maturing spring potato cultivation, plastic film mulching, small arch tunnels, or greenhouse covering are suitable. Potato production in double-cropping regions uses ridge cultivation, preferably sowing on a sunny slope, on the west or south side of the ridge. Plant about 5500 plants per mu. For single-row planting, ridge height is 15-20 cm, with row spacing of 60 × 23 cm; for double-row planting, ridge spacing is 1 m, ridge width is 60 cm, ridge height is 15-20 cm, large row spacing is 60-70 cm, small row spacing is 40-30 cm, and plant spacing is 27 cm. Potatoes can be intercropped with corn, cotton, watermelon, taro, pepper, etc.

4. Sowing method. Choose to sow after a cold wave has passed and the temperature has risen, using east-west rows on a sunny slope. Before sowing, apply chemical fertilizer in a band along the sowing furrow, and shallowly hoe once to mix the fertilizer with the soil, ensuring the seed potatoes do not directly contact the chemical fertilizer to prevent seedling burn. When sowing, separate long sprouts from short sprouts to prevent large seedlings from suppressing small ones after emergence. After sowing, press appropriately to eliminate large clods, and use a rake to lightly pat or lightly sweep the ridge surface before covering with film.

V. Control of Major Diseases and Pests

1. Viral disease. This is the main cause of varietal degeneration and yield reduction in potatoes, so it should be a key focus of prevention and control. Use disease-resistant varieties and virus-free seed potatoes; adjust the sowing period, sow early and harvest early, avoid the peak migration of aphids, reduce aphid damage and transmission, and avoid the effects of high temperatures; promptly and effectively control virus-transmitting insects: aphids, whiteflies, tea yellow mites, etc.; immediately remove infected plants and use chemicals to create a barrier around them. Chemical control: at the early stage of disease, spray a mixture of sugar + vinegar + liquor + goat milk, or 1.5% Zhibingling II emulsifiable concentrate at 1000 times dilution, or a mixture of Tianfengsu + zinc sulfate + human antiviral ribavirin + goat milk.

2. Late blight. It easily occurs under conditions of low temperature and high humidity around flowering. Use spraying for prevention, focusing on the underside of leaves. Around flowering, spray preventively with 70% mancozeb wettable powder at 600 times dilution, or 25% metalaxyl wettable powder at 500-800 times dilution, or 58% metalaxyl-mancozeb wettable powder at 800 times dilution, once every 7 days for 3 consecutive times.