Response Of Root Morphological Characteristics To Soil Water Change Of Two Native Species In Loess Hilly-gully Region Under Intercropping

In order to clarify the relationship between root morphological characteristics ofBothriochloa ischaemum and Lespedeza davurica under different soil water conditions in theloess hill-gully areas of China, one pot experiment was conducted to investigate the rootbiomass, total root length, root surface area, root average diameter, specific root length andspecific root area under three soil water regimes, i.e. sufficient water supply (HW,80±5%FC),moderate water stress (MW,60±5%FC) and severe water stress (LW,40±5%FC) and sevencombinations of the two species(B0D12、B2D10、B4D8、B6D6、B8D4、B10D2�'�B12D0)(Bstands for B. ischaemum and D stands for L. davurica). Besides, at the three main growthperiods (e.g. L. davurica: budding, flowering and grain filling stage), soil water contents wereimproved separately from MW to HW (MHW-1、MHW-2and MHW-3), LW to HW(LHW-1、LHW-2and LHW-3) and MW(LMW-1、LMW-2and LMW-3), respectively. Root biomassand morphological characteristics of the two species under different soil moisture treatmentsat the end of growth period were measured and calculated. The main results were as follows:1. Whether in monoculture or mixtures, water stress decreased root biomass productionof B. ischaemum and L. davurica. B. ischaemum and L. davurica root biomass in monoculturewere less than both mixtures, respectively under B2D10and B10D2mixture proportion is thelargest, mixtures can promote root biomass accumulation of both species.2. Under three water treatments (HW, MW and LW), total root length, root surface areaand root average diameter of B. ischaemum and L. davurica in monoculture under the HWand MW were significantly greater than LW, and special root length and special root area of B.ischaemum under LW is the largest, while L. davurica under the MW is the largest. The totalroot length, root surface area, root average diameter, special root length and special root areaof B. ischaemum and L. davurica under B2D10and B10D2mixture respectively is the largest. After water improvement three times e.g. from MW to HW (MHW), LW to HW andMW(LHW and LMW), total root length, root surface area, root average diameter, special rootlength and special root area of B. ischaemum and L. davurica are greater than LW and MW,respectively.3. Under different water treatments, total root length and root surface area of B.ischaemum and L. davurica was significantly positive correlation with root biomass, whileroot average diameter changed little. Meanwhile, the total root length, root surface area,average diameter, special root length and special root area of B. ischaemum and L. davuricawere obviously larger under B2D10and B10D2.In summary, sufficient water supply was favable to root biomass accumulation and rootmorphology formation of the two species. Appropriate mixture proportion could displaycomplementary effects to maximize biomass production of the two species.