Selection, retention and storage of sweet potato species

Timely harvest sweet potato harvest is too early, the yield is low; too late harvest, easy to suffer from freezing, affecting storage. Therefore, it is generally best to start harvesting when the temperature is about 18 ℃, and finish harvesting when the temperature is above 10 ℃ (that is, before the dry frost period). Generally, spring melons for dry use are harvested first, and then summer sweet potatoes are harvested for planting.

Carefully selected melon pieces in the harvest selection of sweet potato varieties, must be carefully cut to avoid trauma. In order to produce more seedlings, produce strong seedlings and reduce the cost, a melon block with a root of 150ml and 200g should be selected as a seed. The selected melon pieces should be disease-free, waterlogged-free, and have the typical characteristics of this variety. When harvesting, it is best to cut seedlings in the morning, harvest in the morning, and enter the cellar in the afternoon.

Large house cellar or cellar storage is used for cellar storage. Melon seeds should be strictly disinfected in the old cellar before entering the cellar, such as spraying melon cellar with 50% carbendazim 600 times solution or 5% carbendazim 500 times solution and so on. When storing sweet potatoes, spray each layer of sweet potatoes evenly with the diluent of "sweet potato insurance". The special management measures for the storage of sweet potatoes in Dawu cellar are introduced as follows: in the early stage of entering the cellar (15 ℃ for 20 days), the temperature in the cellar should be heated for 24 hours so that the temperature in the cellar can reach 35 ℃-38 ℃ and be kept for four days and nights. After opening the skylight, dehumidifying and cooling, the pit temperature was reduced to 15 ℃ after 24 hours. In the middle stage of storage (20 days after entering the cellar to early February of the next spring), it was mainly heat preservation and heating to prevent melon seeds from cold injury, and the pit temperature should be stabilized at 12 ℃-13 ℃. In the later stage of storage (early February to seedling raising), the cellar temperature should be opened in time to remove excess carbon dioxide. The sweet potato stored by the above method can be kept fresh for a long time, and the intact rate of sweet potato is more than 96%.