Root distribution,soil characteristics,root distribution and fruit quality affected by different mulching measures in apple orchard in the dry area of eastern Gansu

【Objective】The effects of different mulching measures(conventional tillage,plastic mulching,straw mulching and sand mulching) on apple root and soil properties in rain-fed highland of the Loess Plateau were studied.【Methods】Twelve years old apple trees were used as materials,using soil profile method and stratified sampling,and different orders of roots(diameter ≤2 mm,2-5 mm,5-10 mm and ≥10 mm) were collected in soil profile to investigate the spatial distribution,root biomass,root length and surface area. Soil bulk density and soil porosity at different soil layers were determined.【Results】Roots of CK treatment distributed mainly in soil layer of depth of 20-60 cm with a distance of 0-90 cm from the trunk. Roots distributed mainly in the layer of 0-100 cm in depth and in a distance of 0-120 cm from the trunk with the treatment of straw and sand mulching. Roots in 20-40 cm close to the ground were the most intensive. Mulching made the horizontal root distribution similar to the CK,but in vertical distribution more roots was in 0-20 cm layer,accounting for 36.06% of the total root system. Mulching treatment reduced fine root diameter,increased the ratio of root length,and decreased the distribution depth of large root. Soil bulk density,soil water content and porosity showed a highly significant correlation with total root length,root biomass,root surface area and root length density under covering conditions. 【Conclusion】 Mulching treatment made roots distribute shallow significantly,straw and sand mulching increased root distribution in both horizon and vertical depth effectively,and also increased the space and the utilization of available water and fertilizer. It means that tree growth and fruiting can be improved. Soil properties were closely related to the distribution of roots. As a result,considering the root distribution,tree growth,yield and fruit quality,straw mulching is the better way of soil management inapple orchard in dry area of eastern Gansu.