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为提高大树移植成活率及探索修剪方式与大树移植成活生长的关系,以20a以上生广玉兰为试材,以全冠移植为对照(CK),分别采用剪去1/3枝叶量的轻度修剪(QX)、剪去2/3枝叶量的中度修剪(ZX)和不留枝叶的截干回缩修剪(JX)3种方式修剪后移植,经过3a连续试验观察,研究不同修剪方式对广玉兰大树移植成活率和生长的影响。结果表明,与CK相比,3种修剪方式极显著提高广玉兰移植后的成活率和新生叶片数、第2年(2013年)和第3年(2014年)的侧梢数、侧梢长度和底径以及第1年(2012年)和第3年(2014年)冠幅生长;与其他2种修剪方式相比,JX显著提高广玉兰移植成活率、第2年(2013年)和第3年(2014年)的侧梢数、顶梢长度、侧梢长度及冠幅生长以及第3年(2014年)的新生叶片数;显著提高第2年(2013年)和第3年(2014年)的侧梢底径。表明截干回缩修剪更有利于广玉兰大树移植的成活和复壮生长。 相似文献
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以开花时间不同的杜鹃花为试材,研究了不同时期修剪对杜鹃花生长和开花的影响。试验结果表明:修剪可以使早、中花型的杜鹃花花期短期延后,对晚花型的杜鹃花影响甚微。修剪过早,株型不整齐;过晚影响开花的数量和质量。 相似文献
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The quantity of water available for irrigation is getting scarce in many countries and it assumes great importance for assured crop production, especially in view of the erratic behavior of the monsoon. Thus, there is a pressing need to improve the water efficiency of irrigation systems. One-way of improving the efficiency of the irrigation system is reusing the return flow from the irrigation system. This task requires quantification of return flow, which still remains as a grey area in irrigation water management. The estimation of return flow from the irrigation system is usually obtained using thumb rules depending upon the site-specific conditions like command area conditions and soil properties. In this paper, a hierarchical modeling technique, namely, regression tree is developed for return flow estimation. Regression tree is built through binary recursive partitioning. The effective rainfall, inflow, consumptive water demand, and percolation loss are taken as predictor variables and return flow is treated as the target variable. The applicability of the hierarchical model is demonstrated through a case study of Periyar-Vaigai Irrigation System in Tamil Nadu, India. The model performance shows a good match between the simulated and the field measured return flow values. Results of statistical analysis indicated that the correlation coefficients are high for both single as well as double crop seasons. 相似文献
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This paper summarizes several studies on N recycling in a tropical silvopastoral system for assessing the ability of the system
to increase soil fertility and insure sustainability. We analyzed the N2 fixation pattern of the woody legume component (Gliricidia sepium), estimated the recycling rate of the fixed N in the soil, and measured N outputs in tree pruning and cut grass (Dichanthium aristatum). With this information, we estimated the N balance of the silvopastoral system at the plot scale. The studies were conducted
in an 11-year-old silvopastoral plot established by planting G. sepium cuttings at 0.3 m × 2 m spacing in natural grassland. The plot was managed as a cut-and-carry system where all the tree pruning
residues (every 2-4 months) and cut grass (every 40-50 days) were removed and animals were excluded. No N fertilizer was applied.
Dinitrogen fixation, as estimated by the 15N natural abundance method, ranged from 60-90% of the total N in aboveground tree biomass depending on season. On average,
76% of the N exports from the plot in tree pruning (194 kg [N] ha–1 yr–1) originated from N2 fixation. Grass production averaged 13 Mg ha–1 yr–1 and N export in cut grass was 195 kg [N] ha–1 yr–1. The total N fixed by G. sepium, as estimated from the tree and grass N exports and the increase in soil N content, was about 555 kg [N] ha–1 yr–1. Carbon sequestration averaged 1.9 Mg [C] ha–1 yr–1 and soil organic N in the 0-0.2 m layer increased at a rate of 166 kg [N] ha–1 yr–1, corresponding to 30% of N2 fixation by the tree. Nitrogen released in nodule turnover (10 kg [N] ha–1 yr–1) and litter decomposition (40 kg [N] ha–1 yr–1) contributed slightly to this increase, and most of the recycled N came from the turnover or the activity of other below-ground
tree biomass than nodules.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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以塞罕坝机械林场境内的25a生樟子松人工林为研究对象,用标准地调查法对其进行每木检尺,并进行分析比较。结果表明,人工修枝可以促进樟子松人工林胸径的生长,但不影响其树高的生长。 相似文献
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