A study was conducted to discuss the spatial distribution of root system of walnut trees and wheat in walnut & wheat intercropping system by soil coring method at Hetian, in southern Xinjiang. Above-ground biomass, land equivalent ratio and the spatial distribution of roots biological characteristics were analyzed in the different walnut trees (Juglans regia L.) & wheat (Triticum aestivum L.) agroforestry systems.

The results showed that the above-ground biomass of walnut and wheat decreased in the intercropping system. The land equivalent ratio of above-ground biomass of the intercropping systems were greater than 1 compared with the corresponding sole systems (1.620 and 1.617), which represents a higher efficiency in land use. Root diameters in intercropping were lower than it in the corresponding soil in sole systems, but specific root length of intercropped walnut tree and wheat were higher than it in the corresponding soil. Root diameter of intercropped 1-year-old walnut and 2-year-old walnut decreased, respectively, by 30.36% and 26.18% compared with its sole counterpart in 0-40 cm soil of agroforestry ecosystem. Root diameter of intercropped wheat with 1-year-old walnut and 2-year-old walnut decreased by 23.7% and 59.2%, respectively, compared with its sole counterpart. Specific root length of intercropped 1-year-old walnut and 2-year-old walnut increased by 14.3% and 6.7% compared with the sole crops. Specific root length of intercropped wheat with 1-year-old walnut, 2-year-old walnut increased by 2.1% and 22.5% compared with its sole counterpart. The roots of walnut tree and wheat had niche overlap in the 0-40 cm soil. It caused that root diameter and specific root length of intercropped walnut tree and wheat distributed unevenly.

The results can offer clues regarding strategies for suitable pattern and efficient production of walnut trees & wheat agroforestry system in southern Xinjiang.