Effects Of Nutrition On Leaves Photosynthesis Of Fraxinus Mandshurica Seedlings

In this dissertation, one-year-old Fraxinus mandshurica seedlings were selected as experimental materials and cultivated in the modified hydroponic liquid of Hoagland and potted environment. The increment and physiological parameters were measured and analyzed, which included root activities, light response curve, chlorophyll fluorescence parameters, chlorophyll content, soluble sugar, soluble protein and root nitrate reductase etc. The experiment discussed the nutrition influenced mechanism on leaves photosynthesis, which provided basic theory evidences for Fraxinus mandshurica plantations afforestation in China. The conclusions as follows:1. Appropriate competition density was in favor of height and caliper increment and biomass accumulation for Fraxinus mandshurica seedlings. The average caliper of SL-2 treatment was 29 percentage higher than CK, the total biomass (dry weight) was 11 percentage higher than CK. So it was favorable to caliper and biomass accumulation by mixing Larix gmelinii into Fraxinus mandshurica under low density treatments.2. The total biomass (dry weight) of 5N1P treatment was 0.277 gram, which was 42 percentage higher than minimal treatment. The result indicated that high nitrogen concentration was in favor of total biomass accumulation. The root volume of 5P1N treatment was 0.57mL, which was 70 percentage higher than minimal treatment. The result showed that high phosphorus treatment was in favor of prompting root volume and root uptake area, so plant could absorb more nutrition. It was remarkably decreased to apply nitrogen and phosphorus fertilizer for seedling underground and above-ground increment, which improved the root/shoot ratio and root biomass accumulation. Under phosphorus stress, the low phosphorus treatments had stronger ability of absorbing phosphorus than high ones.3. The photosynthesis rate of low density treatments was higher than high ones under interspecific competition. The light saturation point of SL-2 treatment was 2297.6μmol m^-2 s^-1, which was 29 percentage higher than CK. The maximal net photosynthesis...