Abstract: Under irrigation in an oasis in the Tarim Basin, the plant mode of Juglans regia L. intercropped with crops was used more because of the limited area of cultivated land per capita. The research was conducted to investigate the spatial distribution of fine roots (diameter ≤1 mm) of J. regia trees in J. regia wheat intercropping system in the Tarim Basin using the layered digging and image analysis methods. Results showed that, in vertical direction, the fine root length density of J. regia trees increased with the increase of soil depth in layer of 0-40 cm and decreased with the increase of soil depth below 40 cm. The fine roots grew mainly in soil layer of 10-80 cm, their proportion accounted for 65.9% of the total, and that in soil layer below 80 cm was 34.1%. The fine root length density of J. regia trees in the J. regia wheat intercropping system varied with soil depth in an exponential way. In horizontal direction, the proportion of the fine roots 175 cm away from the tree rows was 65.3% of the total. The fine root length density in the middle of alley in the intercropping system was minimum and relatively even. The patterns gained by analyzing the vertical and horizontal distribution of fine roots showed that, under irrigation in the oasis, the soil layer of 10-60 cm within 175 cm away from the trees was the main area for J. regia trees and wheat to compete soil moisture and fertilizer. Thus it is necessary to strengthen the water-fertilizer management in this competition area in farming practice.

Key words: Juglans regia L., winter wheat, intercropping, root length density, spatial distribution, oasis, Aksu, Xinjiang