How can sweet potato cultivation be both good and efficient?

Improved varieties are the most critical factor in increasing yield and income in sweet potato production. So the first step to growing sweet potatoes well is to choose the right variety and raise good seedlings. Below, the cultivation techniques for sweet potato will be introduced.

I. Select high-quality, high-yield, disease-resistant fresh-eating sweet potato varieties

Select high-quality healthy virus-free sweet potato seed potatoes (seedlings): virus-free seed potatoes (seedlings), using shoot-tip meristem culture technology, remove the viruses from degenerated sweet potatoes, restore the varietal characteristics, generally increasing yield by 30%-50%, or even doubling the yield. Healthy seedlings generally have fewer nodes and aerial roots. The standards for selecting strong seedlings are generally: the mass of 100 seedlings ≥400 grams, seedling height over 25 cm, the top three leaves level and even, leaves relatively large and thick, leaves green, stems thick, internodes short, with 5-7 nodes, no aerial roots on the stems, thick sap at the cut, free of pests and diseases, and a seedling age of about 30 days.

II. Choose formal channels and introduce qualified seed potatoes (seedlings)

Sweet potato virus disease, root rot and stem nematode disease are the three major diseases in the northern sweet potato regions. Once infected, they cause reduced yield or even total crop failure. Therefore, the plant quarantine system must be strictly enforced, and it is forbidden to introduce seed potatoes and seedlings from diseased areas. Seed should be introduced from formal scientific research and breeding institutions, and large-scale planting can only be carried out after trial planting.

III. Key points of virus-free sweet potato seedling propagation technology

1. Seed potato preparation: Variety selection should be based on different uses, choosing excellent virus-free sweet potato varieties that have passed national or local approval (or identification), with high quality, high yield, strong stress resistance, good storability and good marketability.

2. Chemical seed soaking: Soak the seed potatoes in a 600-fold dilution of 50% carbendazim for 5 minutes, or in a 500-700-fold dilution of 70% thiophanate-methyl wettable powder for 5 minutes, then take them out and air-dry.

3. Cultivate strong seedlings: Use traditional heated brick beds, solar greenhouses, or electrically heated hotbeds for seedling cultivation. The suitable period for arranging spring sweet potato seed potatoes is one month before spring sweet potato transplanting, generally starting seedling cultivation in mid-to-late March. Choose a sunny day for arranging the seed potatoes, using the slanted arrangement method, with the head pressing over the tail by 1/3, so that the tops are even while the bottoms are not, distinguish heads from tails, keep the sunny side up, and leave appropriate gaps between the two potatoes. The arrangement density should be controlled at 30 kg/sq m. After arranging the seed potatoes, sprinkle a layer of fine soil to fill the gaps between the tuber pieces, water until the bed soil is completely moist, and cover with 3 cm of fine sandy soil on top to keep warm and retain moisture, which helps sprouting.

4. Seedbed management: In the germination stage, the main measures are to increase and maintain temperature. The bed temperature should be kept at 33°C-35°C, and the sprouting time should generally not exceed 3-5 days; in the growth stage, the focus is on promoting growth, combining promotion with control, and the temperature should be kept at 25°C-30°C. At this stage, generally maintain 70%-80% of the maximum soil water-holding capacity. In addition to ventilation and watering, the sweet potato seedlings should also fully receive sunlight; in the hardening stage, when the sweet potato seedlings grow to more than 15 cm, watering and heating measures should be stopped, and the seedbed temperature should be lowered, generally kept at 18°C-20°C; after about 4-5 days, when the seedlings are 25-30 cm tall, they can be harvested. Harvesting should mainly focus on strong seedlings.

5. Harvesting seedlings: When the seedlings grow to 25-30 cm, harvest them promptly. The commonly used harvesting method is the high-cut seedling method, leaving stubble of more than 3 cm to help prevent disease. The best time for harvesting seedlings is early morning, and the cut seedlings should preferably be transplanted the same day to help them survive. If they cannot be transplanted in time, they can be placed in a cool, ventilated place (do not sprinkle water), and try to transplant them early in the following days. After cutting the seedlings, shift to the mainly promoting stage to encourage the growth of small seedlings. After cutting the seedlings, the bed temperature should quickly rise to 30°C so that the wounds heal quickly at high temperature. Do not water on the day of cutting the seedlings; water deeply once the next day. Generally, topdressing can be carried out the day after the second cutting of seedlings, applying 0.2 kg/sq m of ammonium sulfate at one time, and after fertilizing, rinse the leaf surfaces with clean water.