| Poplar has become the main species of plantation at Mid-Latitude plain in China for its rapid growth, high yield, strong in adaptability and easy to intensive management. In this thesis, 22 hybrid progenies of I-72(Populus euramericana (Dode) Guinier cv.SanMartino)×I-63(Populus deltoicds Bartr cv.Harvard) and other 3 extanding clones, eg. I-72, NL-80351(I-69(Populus deltoids Bartr cv.Lux)×I-63) and Nanlin-95 (I-45(Populus euramericana (Dode) Guinier cv.I-45/51)×I-69) were selected as reseach materials, and their growth, physiology, chemical composition and caloric value et.al. were investigated. Based on the Breckin Evaluation, factor analysis and cluster analysis, the superior poplar clones with fast growth and high caloric value were suggested. The mian results were as follows:1. There was significant difference in seedling growth among poplar clones. Annual growth rhythm shaped "S" curve, and Logistic equation could best describe the annual growth rhythm in both seedling height and base diameter for one-year-old cutting seedling of poplar clones. Based on the one-year-old growth cycle, annual growth were divided into three decades, which were initial-stage, fast-growing time and end-stage.2. Six superior poplar clones were selected by Breckin multiple-index Evaluation; they were clones 208,328, 272, 75,347 and 261 in sequence.3. Clones 208 had the highest dry weight in stem, bark and root among all poplar clones, and clones 208, 328, 75,347 and 261 were five higher clones in total biomass.4. Poplar clones showed high net photosynthetic rate and transpiration rate. Net photosynthetic rate for all clones reached peak at nine in the morning during diurnal variations, and the highest achieved in clone 208, reaching 18.4μmol·m-2·s-1; Net photosynthetic rate reached peak at July for seasonal variations, and the highest also occurred in clone 208, getting 22.8μmol·m-2·s-1.5. Both wood basic density and wood moisture content in air dry wood had highly significant difference among poplar clones. Highest wood basic density observed in clone 328, while the highest wood moisture content was measured in clone 208.6. There were significant difference in the crude fibre content, alcohol benzene extractive content, lignin content and ash content among poplar clones. Compared to the other poplar clones, clones 338, 75, 43 and 227 had higher crude fibre content in all biomass components, while clones 261, 275, 328 and 347 got higher alcohol benzene extractive content.The higher lignin content in all biomass components was observed in clones 347, 261, 75 and 208. For the ash content in the components, the lowest was measured in stem, while the highest was found in leaves. The highest ash content in stem was observed in clone 208.7. Carbon contents were about 50% in all components for tested poplar clones, and the content by component was in the order of bark>stem> leaf > root. The highest Carbon content was observed in clones 316, 275, 208 and 347 for stem, root, bark and leaf.8. There was significant difference in gross caloric value among poplar clones. The highest gross caloric value was measured in clones 316, 216, 275 and 183 for stem, root, bark and leaf.9. Through comprehensive evaluation in one-year seedling, clones 208 and 328 were selected as superior clones for bio-energy because of their fine characters. |
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