Abstract: In order to solve the problem of the residual pollution of plastic film that has become the main non-point source pollutant in Hetao irrigation area,five kinds of degradable plastic films were tested in the field experiments in the main sunflower producing areas of Hetao irrigation area.The results showed that film mulching promoted the growth and yield formation of sunflower compared with non-film mulching with the yield increase ranging from 3.4% to 31.8%.The degradation characteristics of five biodegradable membranes and their effects on sunflower growth and yield formation were significantly different due to the different formulations （P<0.05）.The results of surface coverage test showed that the degradation rate of fast film and white film was the fastest,with the induction period of 56 days and 58 days,respectively,followed by middle film and black film,with the induction period of 68 days,and slow film was the slowest,with the induction period of 78 days.All degradable membranes except slow film were completely degraded during the whole growth period.Compared with the ordinary PE film,the degradable plastic film had no effect on the emergence rate and the leaf number of sunflowers.Slow film increased the plant height,while fast film and white film decreased the plant height,the stem diameter,and the flower disc diameter.There was no significant difference in the yield of slow film,middle film,and black film compared with the PE film （P<0.05）.The yield of fast film and white decreased significantly （P<0.05）.In summary,the middle film and black film matched well with the local climate conditions and the sunflower growth,which could not only obtain higher yield but completely degrade without residue.

Key words: Hetao irrigation area, Degradable plastic film, Sunflower, Yield