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Study on Morphological and Physiological Responses of Populus Tomentosa to Pruning

Author: ShangFuHua
Tutor: LiJiYue
School: Beijing Forestry University
Course: Silviculture
Keywords: Populus tomentosa Pruning Grow Chlorophyll content Net photosynthetic rate Transpiration rate Water use efficiency
CLC: S792.11
Type: Master's thesis
Year: 2010
Downloads: 43
Quote: 0
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Abstract


4-year-old plantation of Chinese white poplar (Populus tomentosa Carr.) As the test object, in Granville County, Hebei Province, nursery (experimental field I) and Bazhou, Hebei Wanda tree farms (testing ground Ⅱ) to carry out pruning gradient mild pruning P1, moderate pruning P2, strength pruning P3 to not pruning pruning test control, investigation of different pruning intensity changes Populus tomentosa growth indicators and various processing the yang side nightside of the canopy chlorophyll content and photosynthetic indicators and water use efficiency of the change from physiological mechanism to explain the pruning of the Chinese white poplar plantation growth. The results show that: 1) pruning the first year will affect the DBH growth, with pruning intensity increases the impact of enhanced, but mild of Pruning and moderate pruning and control differences are not significant, the test I strength pruning and controlled a significant difference , test strength II Pruning with control differences are not significant (P gt; 0.05); pruning the the second youngest degrees pruning and moderate pruning the DBH growth greater than the control and severe pruning, a significant difference (P lt ; 0.01). 2) pruning the first year of higher gross poplar have some role in promoting growth, and mild of Pruning and moderate pruning and control differences with (P lt; 0.05); Pruning second youngest degrees pruning tree growth The largest amount, with the other difference was significant (P lt; 0.05). 3) the amount of processing pruning crown width growth the first year less than the control, while the second year than in the control, the amount of crown growth in the two years after pruning with pruning intensity increases and decreases. 4) pruning front and rear leaf area index (LAI) changed greatly increased leaf weight change over time, the leaf area index is still increasing control leaf area index decreased pruning process, and in the second year, leaf volume in August started to decrease, Pruning trees can extend growing season. 5) Test the first year and the second an average annual show that pruning can improve of Populus tomentosa upper leaf net photosynthetic rate (Pn) and transpiration rate (E), and will help to improve the ability of photosynthesis and material synthesis, while the lower part of the control of leaf net photosynthetic rate and transpiration rate at a relatively low level. 6) pruning can improve water use efficiency of clones of Populus tomentosa, and mild pruning Pruning moderate water use efficiency is higher than that of the control and severe pruning. 7) test showed that the chlorophyll content of the control and severe pruning is slightly higher than the the mild pruning and moderate pruning, pruning significant effect on chlorophyll content, but the mild pruning and moderate pruning to improve the chlorophyll a / b value , and the value increases with the increase of high with the sampling tree. From a comprehensive analysis of the growth and photosynthetic physiology, Chinese white poplar plantation canopy canopy lower part should be carried out pruning, the mild pruning and moderate pruning is appropriate.

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CLC: > Agricultural Sciences > Forestry > Forest tree species > Broad-leaved trees > Young
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