Impact of mycorrhizal fungus on the growth and nutrient absorption of Cupressus duclouxiana Hichel seedlings under water stress

The potted seedlings of Cupressus duclouxiana Hichel were tested to study their response characteristics under three different moisture content conditions, normal moisture(25～30%), moderate drought(15～20%) and severe drought(5～10%). Accordingly, the test include four inoculated groups, control group (A), VAM group (B, inoculated VAM), ectomycorrhizal(C, inoculated Ectomycorrhiza) and mixture group (D, VAM + Ectomycorrhiza). The biomass, root morphology and nitrogen content, phosphorus content of Cupressus duclouxiana Hichel seedlings were measured after 150 days. The results show that when the seedlings were inoculated with mycorrhizal fungus under normal moisture, the plant biomass was increased, including above-ground biomass and under-ground biomass. The effect to the contents of nitrogen and phosphorus was mainly on the root. The nitrogen content of roots was respectively increased significantly, by 65.4%, 118.2% and 117.7% in B, C and D group under normal moisture, respectively. The root phosphorus content of C and D group was obvious increased 40.4% and 49.4% compare to control group. The effect to root morphology was also significant, the D inoculated treatment were higher than that in controlled treatment on root length and surface area. Under mediate drought, there was significant difference among B, D and A in N content in roots, but significant difference among C, D and A in leaves. And there was significant difference among C, D and A in P content in roots and leaves. The trend of positive effect to root morphology was D＞ C＞ B＞ A. Under severe drought condition, the mycorrhizal fungi did not affected the plant biomass and nutrient content as well as root morphology. In brief, except for under severe drought condition, the mycorrhizal fungi would improve nutrient absorption and increase the biomass and benefit for enhancing survival rate of C. duclouxiana Hichel.