Key Cultivation Techniques for Winter-Planted Potatoes in Guangdong

Guangdong's warm winter and abundant water sources give it resource advantages for developing winter-planted potatoes. The earliest winter-planted potatoes brought to market in Guangdong are a full 3 months earlier than those from other regions, making them the earliest fresh potatoes to reach the market in the world, with a market advantage. Winter-planted potatoes are currently one of the more ideal winter crops, and they are easy to cultivate, have a short production period, low cost, high yield and wide uses. The main cultivation techniques are as follows:

1. Seed treatment

Before sowing, sprouting and sunning of the seed potatoes is required. After harvest, potatoes have a 50-60 day dormancy period, and all seed potatoes that have not sprouted must be sprouted. Sprouting methods:

1. Separate storage. After buying the seed potatoes, spread them evenly in a dry, ventilated indoor place. If some tubers are found to be partly rotten, cut off the rotten parts.

2. Cutting into pieces. Do this 10 days before planting. The apical bud eyes of the potato sprout first and have an inhibitory effect on the sprouting of the middle and lower bud eyes; if the apical young shoot is damaged or cut off, the other bud eyes will sprout rapidly. In order to obtain more seed potatoes, the potatoes must be cut into pieces. The method is as follows: (1) Cutting method for large tubers of 2.5 liang or more: cut horizontally from the middle, cut the apical part lengthwise into 2-4 pieces, each piece having 1-2 bud eyes and all connected to the apical part. Cut the navel end into 2-3 pieces. (2) Cutting method for tubers of about 2 liang: one horizontal cut and one lengthwise cut, i.e. divided into four pieces. (3) Cutting method for small tubers of about 1 liang: one lengthwise cut, divided into two pieces. (4) Cutting method for small tubers under 1 liang: just cut off 0.6-0.8 cm at the top, do not cut completely through.

3. Disinfection of cut pieces. After cutting the seed potatoes into pieces, spray them with a 0.2% carbendazim or chlorothalonil solution (100 jin of water plus 2 liang of the chemical) for disinfection; just spray them damp. Plant ash can also be applied to the cut surfaces. After drying, carry out sprouting in a sand bed.

4. Sprouting in a sand bed. Carry out sprouting in a dry, ventilated indoor place. Use clean river sand to make a sprouting bed in a ventilated, shady place, spread the cut potato pieces densely and evenly on the ground, then cover with wet river sand 3 cm thick. Densely lay small tubers on the river sand, then cover them with river sand. In this way, one layer of small potato pieces and one layer of wet river sand (2-3 layers is suitable); after laying, cover well with burlap sacks or rice straw. After 6-8 days, when most potato pieces have sprouted (the sprouts have grown to the size of a peanut kernel), they can be sown. During sprouting, frequently check the moisture of the river sand; if too dry, spray water in time, and avoid water accumulation at the bottom.

2. Field cultivation

1. Soil selection. Choose fertile sandy soil with convenient drainage and irrigation. Planting should be carried out immediately after the late rice is harvested, and planting from late October to early November is most ideal. It is not suitable to choose paddy fields with heavy, sticky soil that easily becomes compacted. To prevent the spread of disease, avoid continuous cropping with peanut, tobacco, tomato and other Solanaceae crops.

2. Opening furrows and making beds, applying sufficient base fertilizer. The sowing rate is 80-100 kg per mu. Generally, 3500-4000 plants are planted per mu. Each bed is 1.3 m wide, with a bed surface 80-90 cm wide; planted in double rows, with a row spacing of 28 cm and a plant spacing of 25 cm. It is best to plant in deep furrows and high beds, with furrows about 18-20 cm deep and about 45-55 cm wide, which is good for drainage and field operations. Apply sufficient base fertilizer: apply sufficient organic fertilizer to the field, with 1000-2000 kg of farmyard manure per mu plus 20 kg each of phosphate fertilizer and compound fertilizer and 5 jin of potassium sulfate as base fertilizer, mixed and applied in the middle of the bed

3. Sowing. Open two planting furrows on the bed surface, with a spacing of 28 cm between them; place the seed potatoes, with each seed potato piece spaced 25 cm apart, bud eyes facing up, and cover with soil. Immediately after planting, irrigate once with running water, irrigating to 2 cun below the bed surface; never let it flood over the bed surface, so as to avoid causing the seed potatoes to rot. After 1-2 days, use 2 liang each of Duer and Lasso, or 1 liang of Jindu'er, mixed with 60 jin of water and spray on the bed surface to control weeds, and finally cover with rice straw.

4. Topdressing in the field. (1) When 60-70% of the seedlings have emerged, apply 5 kg of urea and 5 kg of compound fertilizer per mu, mixed with 40 dan of water, as a drench. The compound fertilizer should be soaked overnight to make it easier to dissolve. (2) When the seedlings are about 10 cm high, apply 5 kg of urea and 5 kg of compound fertilizer per mu, mixed with 40 dan of water, as a drench. Also carry out light hilling. (3) After the rows close, apply 5 kg of urea and 7.5 kg of compound fertilizer per mu, mixed with 40 dan of water, as a drench, and carry out heavy hilling. It is best to use low-concentration pig urine water and apply it frequently and lightly; in this way the marketable rate is higher and high yield is easy. Heavy hilling is the key measure determining the marketable rate of potatoes; hill well so that tuber formation and tuber expansion both occur within the soil, avoiding tubers being exposed and turning green.

5. Water management. After planting, keep the soil moist to facilitate early emergence, and keep the soil moist afterward as well. When the field soil surface turns "white" and the soil lacks water, irrigate; irrigate to half the height of the bed, and drain after the water has seeped through the bed surface soil. Before harvest, there should be no waterlogging at the bottom of the field furrows; just keep the soil moist. When there is too much rain, pay attention to drainage; especially in the 15 days before harvest, there must be no waterlogging in the field, to prevent the tubers from absorbing excessive water and cracking or rotting.

6. Pest and disease control. Diseases include late blight, soft rot, viral disease, scab, etc., and insect pests include aphids, potato tuber moths, ladybugs, etc. (1) In the early growth stage in winter, high temperature and drought make the plants prone to aphid damage, which can be controlled with dimethoate; for other pests such as potato tuber moths and ladybugs, use 800-fold trichlorfon solution, 1000-fold 50% dichlorvos emulsion, or 300-400-fold 2.5%% ammonium sulfophosphate emulsion. (2) In the middle and late stages, late blight is likely to occur; use 1:2:200 (copper sulfate:lime:water) Bordeaux mixture to control it early at the initial stage of the disease, and strengthen field management and inspection; immediately pull out diseased plants when found, to prevent the spread of disease. Chemical control: 1000-fold mancozeb solution or 600-800-fold 75% chlorothalonil solution.