| The thesis took Nanlin 95 poplar (Populus×Euramericana cv.) as the research material.the influences on growth and Physiological characteristic of poplar Seedlings was studied in the pot experiment. At the same time, using I-69 polar plantation as a research object, the field fertilization experiment was also conducted to study influences of fertilization on the growth of poplar plantations.The main results were reported as follows:1. The ground diameter, height and leaves number of the seedlings from base cuttings were better than the upper and middle position cuttings. However, the difference in seedling quality was not significant between the upper and central cuttings.2. When the amount of Urea (N fertilizer) reached 9g/pot, it had inhibitory effect on the height growth. For the poplar fertilizztion, when the amount was ranged from 4g to 12g/pot, the effect on height and base diameter growth of seedlings was very significant.The impact of urea on height growth was earlier than the growth of diamete, while the impact of specific poplar fertilizer on the growth of diameter was earlier than height growth.3. Fertilizer treatments made the occurence of fast-growing period delay but the duration prolonged. The earliest occurrence of the fast-growing period was CK, while the latest was observed at the level 1 treatment of urea, with a difference of 16 days. The difference in duration of fast-growing period of seedlings was more than 13 days between the longest duration and the shortest.4. The highest xylem biomass, leaf biomass and total biomass of seedlings was achieved at the treatment of 3g/pot urea, but already inhibited root biomass and bark biomass. The stem biomass and xylem biomass reached the maximum at amount of 12g/pot, then started to decline when overpassed the amount.5. Fertilization treatments increased leaf area, the average single-leaf area and an average of the dry weight of the seedlings. The level 2 of specific poplar fertilizer treatment could grow largest leaf area, hitting to 4195.86cm~2, and with an increase of 122.31% compared with CK. The largest average single leaf (166.46 cm~2) was observed at level 1 of specific poplar fertilizer treatment, with an increase of 52.13% compared to CK. The level 3 of specific poplar fertilizer treatment could obtained the highest dry weight of the single leaf, reaching to 1.16g/leaf, with an increase of 58.90% compared to CK.Generally, urea treatment improved poplar specific leaf area, while specific poplar fertilizer treatment reduced poplar specific leaf area.6. There was a strong correlation between chlorophyll content of leave and poplar seedling biomass at specific poplar fertilizer treatment. Fertilization treatment can significantly improve the values ofΦPSII and the ETR of poplar leave. 7. The vector diagnosis indicated that N, P and K are deficient in unfertilized poplar seedlings and they are limiting factors for poplar seedlings to grow. the content of N in level 2 of Urea is luxurious ,and the level 3 of urea had the toxic action. the content of N, P, K also becomes the luxurious consumption. But has not had the toxic action.8. The results from field experiment showed that the level 3 of urea fertilization and the level 2 of specific poplar fertilizer treatments significantly improved the height growth of poplar plantations, with an increase of 76.47% and 88.24% compared CK, respectively. The concentration of N, P and K in poplar leaves declined from the April to September, while gradually increased from the September to November.
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