Abstract: In order to explore the high-yield cultural technology of purple sweet potato, black plastic film and white plastic film were used to study the effect of plastic mulching on fresh yield, rate of large and medium-sized tuber and economic benefit of purple sweet potato variety Mianyuzi 11. The results showed that plastic mulching could significantly increase the fresh yield of purple sweet potato. Compared to no plastic mulching, black plastic mulching and white plastic mulching increased the fresh yield by 14.64% and 7.81% and increased the rate of large and medium-sized tuber by 15.54% and 14.72%, respectively. Plastic mulching could also improve the economic benefit of purple sweet potato and increase the input-output ratio. The net income increased 11 643.90 yuan/hm² by black plastic film mulching, with an increase of 52.73%. The net income increased 8 799.80 yuan/hm² by white plastic film mulching, with an increase of 39.85%. The effect of increasing fresh yield and economic benefit by plastic mulching was very significant, especially by black plastic film mulching. Therefore we recommend the black plastic film mulching in purple sweet potato planting.

Key words: purple sweet potato, plastic mulching, fresh yield, economic benefit