Detailed explanation of sweet potato storage techniques, teaching you to store them longer

I. Common problems during sweet potato storage

Sweet potatoes are prone to chilling injury, sprouting and rot during storage. Sweet potatoes like warmth and fear cold and damp; the suitable storage temperature is 10-14°C, and the relative humidity is about 80%. Below 10°C, chilling injury easily occurs, with sunken patches appearing on the skin, leading to rot. Sweet potatoes have no physiological dormancy period. During storage, if the temperature is relatively high (15-20°C), the relative humidity is above 85%, and ventilation is poor, they will sprout at any time. Sprouting consumes internal nutrients, making them unfit to eat. The skin of sweet potatoes is thin, and they are easily bruised during harvest. Bruised tubers are easily infected by pathogens. During storage, bruised and infected tubers, if exposed to high temperature and high humidity, are very prone to spoilage and rot. At 15-25°C, soft rot easily occurs; at 23-27°C, black spot disease easily occurs.

II. Key points of sweet potato storage techniques

1. Disinfection of the storage room. The sweet potato cellar used for storage should be cleaned thoroughly and carefully disinfected. Usually, sulfur fumigation is used for disinfection: burn 5-15 grams per sq m at multiple points, fumigate in a sealed environment for 24 hours, then ventilate thoroughly.

2. Timely harvest. Sweet potatoes are susceptible to chilling injury, so they must be harvested at the right time. The air temperature for timely harvest should be 12-15°C, and must not be lower than 10°C. On the day of harvest, after a brief air-drying, they should be packed into baskets (boxes) and put into storage; they must not be left outside overnight, to prevent chilling injury from low nighttime temperatures or rain, which would cause the sweet potatoes to rot.

3. Carefully select the tubers. Sweet potatoes intended for long-term storage must be strictly selected: remove tubers that are bruised, frost-damaged, water-soaked, or damaged by pests and diseases, and choose good-quality tubers of moderate size, undamaged and disease-free, for storage. To prevent disease infection, soak the tubers in a 100-fold dilution of 70% thiophanate-methyl for 3 minutes, take them out, let them dry, and then put them into storage.

4. Curing treatment. The specific method is: immediately after harvest, treat at a temperature of 30-35°C and a relative humidity of 90%-95% for 4-6 days, with a water loss rate of 2%-6%. This allows the damaged surface protective structure of the sweet potatoes to recover. Curing should be carried out in the storage room or cellar. Once curing is complete, the temperature and humidity conditions should be changed to those of normal storage, and the tubers should not be moved again afterward, to prevent new wounds.

5. Strengthen management. Management should be strengthened during sweet potato storage. In the early storage period, if the storage temperature is high and the humidity is high, the tubers are prone to sprouting or becoming diseased. Therefore, ventilation should be turned on to lower the temperature and remove moisture. In the middle storage period, the outside temperature is very low, and sweet potatoes are susceptible to chilling injury. During this period, appropriate insulation should be maintained (keep above 12°C) to avoid low-temperature damage. If sweet potatoes are stored in a cellar, note that: in the later storage period, as the outside weather warms up and the temperature gradually rises, the respiration of sweet potatoes increases. At this time, ventilation in the cellar should be strengthened to prevent the accumulation of carbon dioxide released by respiration from causing a “stuffy cellar” and rotten tubers.

6. Pay attention to methods. The capacity of sweet potatoes put into the cellar must not exceed 2/3, leaving space to facilitate ventilation and moisture removal and prevent a “stuffy cellar”. The storage temperature should preferably be 10-14°C. Strengthen ventilation and moisture removal, keep the relative humidity at about 80%, and prevent freezing, stuffiness and rot. During storage, if diseased tubers are found, they should be picked out immediately to prevent spread.