Abstract: 【Objective】The planting area of sweet potato is 6.7 million square hectometer and its annual output is 100 million tons in China. However, the mildew deterioration rate of sweet potato production is about 15% due to the improper storage. The respiration type, storage temperature and main storage diseases of postharvest sweet potato were studied. To provide a theoretical basis and technical parameters for sweet potato storage, the effects of different fresh-keeping technologies on storage physiology and mainly diseases of sweet potato were investigated in the paper.【Method】Qinshu5 sweet potato as a main cultivated variety in Shaanxi was stored at (10±0.5), (11±0.5), (12±0.5) and (13±0.5)℃, respectively. The respiration intensity was evaluated by air flow method, the storage temperature was determined by comparing the decay index, the storage disease pathogen was identified by Koch's validation, ITS sequence analysis and morphological characteristics, and the dosage of thiabendazole (TBZ) fumigation was determined by comparing the spore breeding situation. The common sweet potato fungicide mildothane powder was used as the control. The polygalacturonase (PG) activity was measured by DNS colorimetry, amylase activity and superoxide dismutase (SOD) activity were determined by reagent kit, ascorbic acid content was determined by 2, 6-dichloro phenol indophenol titration, starch content was determined by acid hydrolysis method, reducing sugar content was determined by DNS colorimetry, and original pectin content was determined by carbazole colorimetry. The changes of SOD activity, amylase activity, PG activity, starch content, reducing sugar content, ascorbic acid content and original pectin content of Qinshu 5 sweet potato treated with TBZ fumigation, pre-storage low temperature (3, 4, 5℃), plastic bag packaging during storage were measured. Decay index and commercial percentage were calculated during the late period of storage. The statistical software Excel 2010 was used to analyze the test data and Duncan’s method was applied for the multiple comparison. 【Result】 The respiration type of sweet potato was climacteric variant and the optimum storage temperature was 11℃. Alternaria bataticola Ikata was the main pathogen that led to black spot disease during storage. TBZ could inhibit the spore reproduction obviously. The treatment that postharvest sweet potato callused at room temperature, being pre-cooled at low temperature, fumigated by TBZ, packaged with plastic bags, and then stored at 11℃ can significantly restrained the activities of amylase and PG, kept the activity of SOD in a highly active state, reduced the rate of starch convert into sugar, maintained the ascorbic acid content at a high level, delayed the physiological aging process of postharvest sweet potato, and kept the original quality of sweet potato well.【Conclusion】The postharvest sweet potato was placed to callus for 5 days under natural conditions, treated with low temperature at 4℃ for 2 days, then the storage temperature went up slowly with 1℃ every day, until it came to 11℃ the long-term storage started. During the storage temperature rising, the sweet potato was treated with 4.5% TBZ fumigant at the dosage of 6 g•m-3 for 3 hours and stored in plastic bags, with the rotten index being 0.185 and the commercial percentage being 93% after 210 days of storage. Under the suitable temperature, the sweet potato was preserved well by the callus before storage, low temperature treatment, TBZ fumigation combined with plastic package. Meanwhile it had a good safety and hygiene.

Key words: sweet potato , postharvest physiology , Alternaria bataticola Ikata , storage technology