Selection and Storage Methods for Sweet Potato Seed Tubers

Timely harvest. If sweet potatoes are harvested too early, the yield is lower; if harvested too late, they are prone to frost damage, which affects storage. Therefore, it is generally best to begin harvesting when the temperature is around 18°C, and to finish harvesting when the temperature is above 10°C (that is, before the killing frost period). Generally, spring sweet potato fields used for slicing and drying are harvested first, followed by summer sweet potatoes grown for seed use. 

Selecting tubers carefully. When harvesting and selecting good sweet potato varieties, be sure to dig and cut carefully to avoid mechanical injury. In order to produce more sprouts, strong sprouts, and lower costs, tubers weighing 150-200 g should be selected as seed. The selected tubers must be free of disease and waterlogging damage, and must also have the typical characteristics of the variety. At harvest time, it is best to cut the vines in the morning, dig in the forenoon, and put the tubers into storage in the afternoon.

Storage in pits. For storage in a large storage house or pit, the old storage facility must be strictly disinfected before the seed tubers are placed inside, for example by spraying the storage pit with a 600-fold dilution of 50% carbendazim or a 500-fold dilution of 5% Ansuo Junduqing aqueous solution. When storing sweet potatoes, each layer of sweet potatoes should be evenly sprayed with a diluted solution of "sweet potato preservative." The special management measures for storing sweet potatoes in a large storage house are introduced as follows: in the early storage period (15-20 days after being placed in storage), the temperature should first be raised for 18-24 hours so that the temperature inside the storage facility reaches 35°C-38°C, and this should be maintained for four days and nights. After that, open the skylight to release moisture and lower the temperature, and after 18-24 hours reduce the storage temperature to 15°C; in the middle storage period (from 20 days after being placed in storage to early February of the following year), the main tasks are heat preservation and temperature increase to prevent the seed tubers from cold damage, and at this time the storage temperature should remain stable at 12°C-13°C; in the late storage period (from early February to seedling raising), open the storage facility in time to inspect and remove excess carbon dioxide. Sweet potatoes stored by the above method keep fresh for a long time, and the intact rate of the sweet potatoes reaches more than 96%.