How can high yield be achieved in delayed autumn cultivation of potatoes?

Delayed autumn cultivation of potatoes means that potatoes planted in the open field are covered with a shed and plastic film before the arrival of early frost, so that they are protected from early frost damage, make full use of late autumn light conditions, extend the potato growth period, increase yield, improve market quality, and achieve high yield and high efficiency.

1. Site selection

Choose plots with loose, slightly acidic soil, rich in organic matter, deep plow layer, and easy drainage and irrigation. The previous crop is best to be millet, wheat, or corn; for vegetables, the previous crop is best to be scallions, garlic, celery, or carrots. Remember that continuous cropping must not be practiced, and the previous crop must not be a plot of Solanaceae crops, in order to reduce potato diseases and nutrient deficiency symptoms.

2. Seed potato treatment

1. Seed selection: The seed potatoes are required to have the characteristics of this variety, be virus-free whole small tubers of 30-50 g, and be free of deformities, disease, and rot. Planting whole tubers has the advantages of drought resistance, full and strong seedlings, giving full play to the apical dominance of seed potatoes, obtaining high yield, and reducing disease transmission.

2. Sprouting: Generally, sprouting is carried out 30-40 d before sowing. It can be done indoors or in a greenhouse. First spread 1 layer of wet river sand on the ground, place 3 layers of seed potatoes on the sand, and cover the seed potatoes with 1 layer of wet sand. The moisture of the sand should be such that it does not form a ball when held in the hand, and the temperature should be maintained at about 15°C. When the sprouts are about 1-2 cm long, they can be sown.

3. Sowing

1. Fertilization and land preparation: Before sowing, apply base fertilizer in combination with plowing. Apply 3000 kg of fully decomposed organic fertilizer per 667 sq m. In drought, water should be applied to preserve soil moisture and ensure water supply before emergence. Level the soil and rake it fine to facilitate sowing.

2. Sowing time: About 1 week after the Beginning of Autumn. If the temperature is still very high, delay sowing for a few days. Sowing too early, when the air temperature and soil temperature are too high, easily causes seed rot, dead seedlings, and severe pest damage, with uneven emergence. Sowing too late shortens the effective growth period and affects yield.

3. Reasonable close planting: The planting density is closely related to soil conditions and water and fertilizer conditions. Generally speaking, plots with good soil conditions and high water and fertilizer conditions can appropriately increase density, and vice versa can appropriately reduce density. In most cases, generally about 5000 plants per 667 sq m. If less than 4500 plants per 667 sq m, it is easy to produce a relatively large proportion of large tubers, and these large tubers are prone to hollow heart. The main cause of hollow heart is uneven supply of water and fertilizer, especially after a period of drought followed by rainfall, when the supply of water and nutrients is insufficient and the tubers expand rapidly. This is worth noting. When the drought lasts too long and rainfall occurs relatively late, tubers of normal size can also develop hollow heart.

4. Sowing: Sow in shallow furrows opened on flat ground, then cover with soil and form ridges, so that the seed potatoes are located in the middle and upper part of the ridge, reducing soaking of the seed potatoes by accumulated water in the furrows. Ridging helps with watering to lower temperature or drainage during waterlogging. The soil cover should not be too thick; the depth is 8-10 cm, so that the potatoes emerge as quickly as possible. After sowing, smooth the ridges to preserve soil moisture, and spray the herbicide acetochlor. Apply 50 kg of compound fertilizer, 25 kg of potassium sulfate, 1.5 kg of borax, 1.5 kg of zinc sulfate, and 1 kg of phorate per 667 sq m.

4. Field management

1. Watering and earthing up: At the bud stage, carry out the first intertillage, and combine it with weeding and earthing up. High earthing up is required to prevent the potatoes from turning green. Thoroughly pull out diseased plants (the surrounding soil should also be removed) and off-type plants, and carry out the first watering. Complete earthing up before the plants close the rows at the flowering stage, and according to rainfall conditions, water a second time at the full flowering stage to promote the plants to enter the tuber-setting stage earlier. Stably supplying the water and nutrients needed for potato growth is an important measure to ensure high yield and high efficiency of potatoes; otherwise, hollow heart and secondary growth are very likely to occur. If heavy rain falls during the growth period, drain promptly and immediately loosen the soil with a hoe so that the soil is loose and breathable. Stop watering 1 week before harvest.

2. Film-covering time: Before the arrival of Frost's Descent, cover with film when the daytime temperature is below 15°C and the nighttime temperature is below 7°C. In order to withstand heavy snow and strong winds, a steel pipe structure is generally used, and ordinary agricultural film is selected for the greenhouse film.

3. Temperature control and ventilation: Ventilate appropriately according to weather changes. When the temperature outside the shed is above 20°C during the day and above 10°C at night, ventilate day and night, maintaining 20-25°C during the day and 10-15°C at night inside the shed. When the temperature outside the shed is about 15°C during the day and about 7°C at night, do not ventilate at night to avoid frost damage. If humidity inside the shed is high, ventilate promptly during the day.

4. Pest and disease control: Mainly prevent late blight. When the leaf wetness period exceeds 10 d and the temperature is between 15-20°C, late blight infection is very likely to occur. Once such climatic conditions appear, protective fungicides should be sprayed before late blight lesions are found: 70% Kelu at 700-800 times, Score 70-100 g/667 sq m. To control aphids, use 5% pirimicarb at 2000 times, and 1% abamectin at 2000 times.

5. Harvesting

About 100 d after emergence, harvest at the proper time according to the size requirements of market potatoes and weather conditions. Harvest on sunny days. After the tubers are slightly dried, remove diseased, insect-damaged, rotten, deformed, green, and cracked tubers, then grade and package them.

6. Economic benefit analysis

Cultivation experiments in recent years have shown that varieties with a long growth period obtain relatively higher economic benefits, because such varieties can be harvested as late as the end of December, greatly increasing yield, and at this time it is deep winter, when various vegetables are relatively scarce, and potatoes are also a relatively popular vegetable, so sales volume is large and prices are high. Based on an increase of 500-750 kg per 667 sq m and a wholesale price of 1.50 yuan per kg, the increased economic income per 667 sq m is 750-1000 yuan.