The Study Of The Roots Interaction In Jujube/Wheat Agroforestry Systems At Southern Xinjiang

Jujube intercropping wheat mode is widely used in southern Xinjiang, but the belowgroundinterspecific competitive interactions in agroforestry systems was few studied, which affecting theresources efficiently allocated. To take full advantage of the limited land resources in southern Xinjiangand ensure the security and stability of food production. A field experiment was conducted at the HetianAgricultural Technology Extension Center in southern Xinjiang. It was that these aboveground biomass,economic yields and land equivalent ratio were analyzed in the different jujube trees (Ziziphus jujuba Mill.)/wheat (Triticum aestivum L.) agroforestry systems. Roots of jujube and wheat were sampled by auger inthe maturity of winter wheat and flowering stage of jujube trees, and the spatial distribution of rootsbiological characteristics were analyzed, to reveal the intercropping advantage and belowgroundinterspecific root interactions of jujube trees/wheat agroforestry system. The results obtained can offer animportant strategy for suitable pattern and efficient production of jujube trees/wheat agroforestry system insouthern Xinjiang. The main results were as follows:1. There was a significant decrease in the yield and above-ground biomass when wheat wasintercropped with jujube trees. However, all jujube/wheat intercropping systems, of which LER valueswere larger than one, had a higher combined mass production and land use efficiency than thecorresponding monocultures.2. The root surface area density, root volume density and root biomass density of monoculture orintercropped wheat was concentrated in the0–20cm soil profile,40–100cm soil profile was sparseareas. The root surface area density, root volume density and root biomass density of monoculture orintercropped was concentrated in the0-60cm soil profile,60–80,80–100cm soil was sparse areas. Thebelowground interactions of the root systems of the wheat and jujube intercropping in0–20cm soilprofile leaded to the relative proportion of the root surface area density, root volume density and rootbiomass density of both intercropped wheat and jujube were increased. However, the belowgroundinteractions of the root systems of the wheat and jujube intercropping in60–80cm soil profile leaded tothe relative proportion of the root surface area density, root volume density and root biomass density ofboth intercropped wheat and jujube were decreased.3. The roots of both intercropped wheat and jujube had smaller root surface area density, root volumedensity, root biomass density and root diameters and higher specific root lengths at corresponding soildepths than did sole wheat and jujube. However, the SRL values of intercropped wheat and jujube werelarger than those of monoculture wheat and jujube. The older the jujube the larger were these root surfacearea density, root volume density, root biomass density and root diameters of jujube, the smaller were theseroot surface area density, root volume density, root biomass density and root diameters of wheat. However,the older the jujube the larger were the SRL values of intercropped wheat. Because5and7-year-old jujubehave more developed root system, the root surface area density, root volume density and root biomass density of intercropped jujube, compared to those of monoculture and jujube, had no significant decline inthe corresponding soil profile of the respective sampling point. However, in the wheat/3-year-old jujubetree systems, because3-year-old jujube have not yet developed root system,0–20,20–40cm soil layer,the root surface area density of intercropped3-year-old jujube was decreased significantly compared tomonoculture3-year-old jujube；in the0–20cm soil layer, the RD and SRL of wheat intercropped3-year-old jujube and sole wheat had no significant differences. The smaller the distance from the jujube,the larger was root surface area density, root volume density, root biomass density and root diameters ofjujube, the greater influence there was on the root surface area density, root volume density, root biomassdensity and root diameters of wheat, so the smaller the distance from the jujube, the smaller was rootsurface area density, root volume density, root biomass density and root diameters of wheat; but the greaterwas the SRL of intercropped wheat. Jujube tree roots showed a mainly downward trend and extendedlaterally150cm from the trees resulting in the roots of the jujube trees and the wheat having niche overlapat a soil depth of20–40cm, thus showing plasticity to adapt to the belowground competition inagroforestry systems. The root surface area density, root volume density、 root biomass density, rootdiameters and SRL of wheat and jujube trees in agroforestry systems was different, being belowgroundinterspecific competition, the distance from the jujube and the age of jujube affected.