The Study Of The Roots Distribution Characteristics Interaction In Walnut/Wheat Agroforestry Systems In Southern Xinjiang

Walnut trees intercropping wheat mode play an important role in agricultural production in southern Xinjiang, but the belowground interspecific competitive interactions in agroforestry systems was few studied, which affecting the resources efficiently allocated. To take full advantage of the limited land resources in southern Xinjiang and ensure the security and stability of food production.This paper selects Hetian Agricultural Technology Extension Center as the research area which located in southern Xinjiang, with soil coring method, Win-RHIZO root analysis system was conducted to measure root morphology parameters, It was that these above ground biomass, land equivalent ratio, root diameter, specific root length, root surface area density and root dry weight density were analyzed in the different walnut trees(Juglans regia L.) / wheat(Triticum aestivum L.) agroforestry systems. The field experiment studied the distribution patterns of roots in walnut /wheat agroforestry system to reveal below ground interspecific root interactions and the intercropping advantage, the results obtained can provide theoretical basis for the walnut/wheat intercropping system in Southern Xinjiang and improve the efficiency of intercropping system land use. Main conclusions were as follows:1. In intercropping systems, the results showed that the above-ground biomass of intercropped walnut trees and wheat were lower than those in their monoculture systems. However, all intercropping systems, of which LER values were larger than one. It mean that land use efficiency were a higher than the corresponding monocultures.2. In intercropping systems, the tendency of spatial distributions was consistent in root diameter, root surface area density, root volume density and root dry weight density of monoculture walnut trees or intercropping walnut trees. In horizontal directions, it was decreasing with increasing distance from the walnut trees. In vertical directions, it was decreasing with increasing of soil depth, the tendency of spatial distributions was consistent in root diameter, root surface area density, root volume density and root dry weight density of intercropping wheat. In horizontal directions,it was increasing with increasing distance from the walnut trees. In vertical directions, it was decreasing with increasing of soil depth.3. In intercropping systems, root diameter, root surface area density, root volume density and root dry weight density intercropped walnut trees and wheat were lower than those at corresponding soil depths in their monoculture systems. However, the roots of intercropped walnut trees and wheat had higher specific root length than those of monoculture walnut trees and wheat; Those of root diameter, root surface area density, root volume density and root dry weight density of walnut trees root were increasing with age increasing. Those of root diameter, root surface area density, root volume density and root dry weight density of intercropped wheat were decreasing with age increasing, but specific root length of intercropped wheat was increasing. There were no significant differences in root diameter, root surface area density, root volume density and root dry weight density of monoculture walnut trees or intercropping walnut trees, However, the roots of two-year-walnut trees had higher root diameter, root surface area density, root volume density and root dry weight density than those of one-year-walnut trees.4. Root diameter of intercropped 1-year-old, 2-year-old walnut decreased by 36.901% and 25.009% compared to its sole walnut in 0~40 cm soil of agroforestry ecosystem, Root diameter of intercropped wheat with 1-year-old, 2-year-old walnut decreased by 6.98% and 18.10% compared to its sole wheat in 0~40 cm soil of agroforestry ecosystem. Root surface area density of intercropped 1-year-old, 2-year-old walnut decreased by 32.59% and 25.44% compared to its sole walnut in 0~40 cm soil of agroforestry ecosystem; Root surface area density of intercropped wheat with 1-year-old, 2-year-old walnut decreased by 25.998.% and 44.516% compared to its sole wheat in 0~40 cm soil of agroforestry ecosystem. Specific root length of intercropped 1-year-old, 2-year-old walnut increased by 14.328% and 6.659% compared to its sole walnut in 0~40 cm soil of agroforestry ecosystem, specific root length of intercropped wheat with 1-year-old, 2-year-old walnut increased by 2.054% and 22.494% compared to its sole wheat in 0~40 cm soil of agroforestry ecosystem.The root diameter, root surface area density, root volume density and root dry weight density of monoculture or intercropped wheat was concentrated in the 0~40 cm soil profile, but, 40~60 cm, 60~80 cm, 80~100 cm soil was sparse areas. The root diameter, root surface area density, root volume density and root dry weight density of monoculture or intercropped walnut trees was concentrated in the 0~40 cm soil profile, 40~100 cm soil profile was sparse areas. Because the root of walnut trees showed a mainly downward trend and extended laterally 150 cm from the trees resulting in the roots of the jujube trees and the wheat having niche overlap at a soil depth of 20~40 cm, thus showing plasticity to adapt to the below ground competition in agroforestry systems, resulting in the roots of the walnut trees and the wheat having niche overlap a in the vertical distribution, also having the dislocation phenomenon. Therefore, the root of walnut trees can use the deep soil moisture and nutrient in the deep soil and can improve utilization efficiency of deep soil resources in the growers intercropping system.