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51.
52.
In this study, we subjected the root systems of eight Eucalyptus hybrids currently cultivated in southern China to heterogeneous phosphorus stress to provide a scientific basis for the selection of a highly phosphorus-efficient Eucalyptus variety. When the ability of these hybrids to locate phosphorus under different experimental conditions (phosphorus supply in a homogeneous or heterogeneous manner vs. no phosphorus supply) was compared, the main growth characteristics of Eucalyptus, such as plant height, diameter, dry mass, and phosphorus content, significantly improved when the phosphorus supply was increased from no phosphorus or heterogeneous phosphorus (half of the phosphorus amount) to homogeneous phosphorus. Across these three conditions, the growth traits of different Eucalyptus hybrids differed significantly, indicating different adaptabilities of the hybrids to various phosphorus conditions. The growth traits of the aboveground tissues of Eucalyptus under different phosphorus conditions were largely influenced by the morphology of the underground root system. In addition, the root morphology of Eucalyptus under heterogeneous phosphorus treatment suggested that there were two mechanisms for locating nutrients. Eucalyptus hybrids such as Urophylla 3229, Grandis 9, Guanglin 3, 201-2, and Dunn produced more roots proximal to the phosphorus supply; the other hybrids, Urophylla 3216, Grandis 5, and Guanglin 9, relied mainly on the growth of roots opposite the phosphorus supply to obtain adequate nutrients for growth. With these two strategies, a wide range of nutrients was obtained, root distribution was greater, more soil volume was covered, the contact area of the roots with soil phosphorus was increased, and the uptake of phosphorus by the root system was increased. These results demonstrate that Eucalyptus relies on changes to morphological characteristics of the root system to increase accessibility to phosphorus resources. 相似文献
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55.
紫丁香扦插育苗技术试验研究 总被引:5,自引:0,他引:5
本文论述了如何运用ABT等科技手段处理紫丁香以提高它的扦插成活率问题。 相似文献
56.
Differentiating from normal wood, pit membranes in wetwood of subalpine fir contain bacteria of water drop shape or orbicular
shape, and flaky shape, as observed using Scanning Electronic Microscope. Not only are ray parenchyma cells in wetwood partially
degraded but also margo strands in pit membranes are somewhat degraded by bacterial activities. Most of the bordered-pit membranes
in normal wood are unaspirated in green conditions and the proportions of aspirated pits in earlywood and latewood account
for only 6.8% and 13.4%, respectively. Nevertheless, most of the bordered-pit membranes in wetwood are aspirated in green
conditions and the proportions of aspirated pits account for 77.7% and 72.1%, respectively. The problem of hard-to-dry for
subalpine fir could be reasoned from the considerable amount of aspirated pit membranes in wetwood.
__________
Translated from Journal of Nanjing Forestry University (National Science Edition), 2006, 30(1): 53–56 [译自: 南京林业大学学报 (自然科学版), 2006, 30(1): 53–56] 相似文献
57.
Four new sesquiterpenes, myrrhterpenoids K-N (1-4) have been isolated from the resin of Commiphora myrrha. Their structures and relative configurations were elucidated by spectroscopic methods (IR, ESIMS, HR-ESIMS, 1D and 2D NMR). Compounds 1 and 4 showed neuroprotective effects against MPP(+)-induced neuronal cell death in SH-SY5Y cells. 相似文献
58.
板式家具结构强度分析 总被引:6,自引:2,他引:6
50年代后期,Kotas对五面箱体的结构强度进行了研究,并且写了一本家具设计手册。Eckelman从板式部件的接合强度及家具的整体结构强度做了许多研究,他提出了板件的刚度与各种形式角接合变形的关系。他和Rabiej对带有横搁板和中隔板的柜体作了综合分析,得出计算公式,可用其计算三角固定一角自由条件下的柜体在受力时的变形。国内主要在家具力学性能测试方面,标准制定方面做了一些研究,在结构强度分析方面尚未进行过研究。 相似文献
60.
为进一步比较不同柳树无性系幼苗生长及光合特性的差异,选择优良柳树无性系,以垂爆109柳SalixבChuibao 109’和旱快柳Salix matsudana var.anshanensis为试材,采用Hoagland营养液水培方法,研究正常情况下垂爆109柳和旱快柳幼苗生长性状和光合特性。结果表明:培养45d后,与旱快柳相比垂爆109柳幼苗的叶片数、叶长、根长、根数、基径无显著差异;垂爆109柳的叶宽、叶间距、新枝长、枝条鲜质量和干质量,根鲜质量和干质量,都明显高于旱快柳(p<0.01)。垂爆109柳和旱快柳的净光合速率有明显的差异,净光合速率值在不同光照强度下均表现为垂爆109柳>旱快柳。垂爆109柳的光饱和点和光补偿点都低于旱快柳,表明旱快柳具有较强的光强利用能力,强光照射对旱快柳的抑制作用较低;而垂爆109柳利用弱光的能力较强。 相似文献