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A questionnaire survey was conducted in different crop-planting areas, and typical sample points were analyzed according to the present situation of plastic film and the residue in soil in the Hetao irrigation area. The results showed that the level of plastic film pollution was moderate, and that the residual amount of plastic film in farmland was 18.20-418.60 kg∙hm-2, with an average value of 131.11 kg∙ hm-2. The residual amount of plastic film was affected by the age of the plastic film mulching, crop type, recovery, soil texture, and other factors, among which the contribution rate of plastic film mulching age was the highest. With the increasing age of plastic film mulching, the residual amount of plastic film increased significantly, and the residual amount of plastic film in plots covered for more than 20 years was significantly higher than that in plots covered for less than 20 years (P<0.05) . The residual amount of plastic film in maize planting areas (132.77 kg∙hm-2) was higher than that in sunflower planting areas (127.88 kg∙hm-2) . Awareness of plastic film recovery was an important factor affecting the residual amount of plastic film in Hetao irrigation area. Recovery methods mainly include manual picking or raking out of farmland. The recovery rate of plastic film in the study area was only 38.10%, and the residual amount of plastic film recycled plots (108.28 kg∙hm-2) was significantly lower than that of non-recycled plots (145.03 kg∙hm-2) . Under the same conditions, the amount of residual film in sandy loam soil with different texture was the highest (153.84 kg∙hm-2) . The investigation results show that Hetao irrigation area can adjust planting structure, strengthen recycling awareness and recycling methods, popularize biodegradable plastic film to reduce plastic film pollution. [ABSTRACT FROM AUTHOR]

This experiment was conducted to screen the suitable mulching type of plastic film for Rosa roxburghii orchard, according to explore the effects of different color plastic film mulching on soil, shoot growth, flowering and fruit setting. Four different colors (colorless was marked as T1, red was T2, green was T3 and black was T4) of plastic film with PE material were selected in this study. The natural grass with no plastic film covering was taken as the control. The differences of soil physical properties, microbial carbon content, shoot growth, flowering, fruit setting and yield performance under different treatments were compared. The results showed that plastic film mulching could increase soil temperature in different degrees, and lead to an earlier phenological period, in which the flowering time of black and red plastic film mulching treatments was 4-5 days earlier than that of the control. Soil physical parameters such as salinity, volume water content, total dissolved solids, electrical conductivity and dielectric constant under the treatment of black plastic film were higher than those under the control, while other plastic films had no such effects but the soil physical properties were more stable. Covering with black and red plastic film could significantly inhibit the growth of weeds, and the biomass of weeds in the covered area was reduced by 88.36% and 89.5% respectively, which was significantly lower than that of other treatments and the control. All plastic film mulching treatments could increase the chlorophyll content of leaves, and green plastic film was the most beneficial to promote the growth of new shoots of R. roxburghii. The colorless and black plastic film mulching could significantly promote the flowering of R. roxburghii, and the fruit-bearing capacity in the early stage increased about 43.8% and 37% respectively compared with the control. Finally, the treatment with colorless plastic film had the most prominent effect of increasing the yield, which was 52.55% higher than that of the control. While the black plastic film lead to more fruit dropping during the fruit development, so that the final yield was only increased by 14.39% compared with the control. The results of this research showed that different color plastic films had their own advantages in improving or stabilizing soil physical parameters, promoting tree growth, inhibiting weeds and increasing yield, and could be used as needed in production. Among them, the colorless plastic film was particularly effective in increasing fruit yield, and could be suggested as the preferred plastic film type for cultivation of R. roxburghii. [ABSTRACT FROM AUTHOR]