杨树切枝杂交技术

林木杂交是选育优良品种最直接有效的途径之一，并能为现代高新技术育种提供原始材料。杨树杂交育种在全世界范围开展以来，选育出了大量的优良品种，对提高杨树生产力起到了非常重要的作用。章就杨树切枝杂交技术作一简单的阐述，主要包括材料的准备、室内切枝杂交、播种育苗等。     

杨树切枝水培杂交育种研究技术

杨树水培杂交是杨树获得新品种的重要而有效的育种途径之一,在杨树良种选育中发挥着重要的作用。我国通过杂交育种先后选育出很多优良的品种。主要阐述了杨树切枝水培杂交育种过程中的一些关键技术。     

浅谈杨树切枝水培杂交

杨树,自然条件下种子少而且不易采集.为选育良种,采用切枝水培杂交技术,便于调整花期,保证父本的纯正,为杨树家系育种奠定良好基础.     

杨树花枝盆栽加温促进生根人工杂交育种技术

杨树杂交育种是杨树改良的最主要途径,国内外绝大多数栽培品种都是通过这一途径选育出来的,因为杂交种可以具有需要的优良品质和适应性.[1-2].除了自然界有少量天然杂交种外,人工杂交是获得杂交种的最主要手段.从种子发育的母本所处的环境来分：一种是在室外大树上的人工杂交,另一种是母本花枝切枝后在室内人工杂交.     

银白杨与黑杨派、青杨派派间杂交育种试验初报

文章以白杨派银白杨为母本,以黑杨派N001或青杨派马氏杨单一花粉或其与白杨派树种的混合花粉(混合比例4∶1)为父本,采用人工切枝水培技术进行杂交,并对杂交子代的生根能力进行测定,为更好地提高杂交技术及选育优良品种提供参考。     

杨树切枝杂交及播种育苗技术

杨树为柳科杨属 (PopulusL .)树种 ,为落叶乔木。目前杨树定向培育已成为国内外的热点问题之一 ,杨树杂交育种对培育胶合板材、纸浆材、大径材及抗性育种 (抗旱、抗寒、耐盐碱等 )有重要意义。杨树自然条件下种子少而且不易采集 ,室外杂交花期、授粉不易控制 ,为达到选育良种的目的 ,采用切枝杂交技术 ,便于调整花期 ,保证父本的纯正 ,为杨树全同胞家系育种奠定良好基础。1　材料的准备1.1　亲本的确定及雌雄株辩别根据育种目的确定杂交的父母本 ,选择生长健壮无病虫害的优良单株作为亲本。同一杨树种的雌雄株比较 ,雌株树冠开扩 ,小枝多而…     

陕林1号和陕林2号杨树无性系的选育

杂交育种是培育杨树优良品种的重要途径之一。二十多年来,我国在杨树有性杂交育种方面获得显著成果。尤其是用引进的欧洲黑杨与原产我国的青杨派树种杂交,选育出了不少速生、抗性强的新品种,在生产中显     

青杨雄株选育、栽培技术要点

青海省大通县实验林场实施杨树优良品种选育的课题时,通过选育杨树优良品种,总结出青杨雄株栽培技术要点。     

杨树杂交的两种新技术

介绍了杨树杂交的两种新技术:室外大树侧倒法和室外切枝扦插法.新技术具有高效、经济、安全等优点,在杨树杂交育种以及其他易生根乔木杂交育种中具有应用价值.     

波氏杨的栽培

<正>青海省大通县实验林场实施杨树优良品种选育的课题时,通过选育杨树优良品种,总结出波氏杨栽培技术要点如下:一、技术关键通过研究扦插培育技术,育苗技术,运用育苗措施,选择优     

论法治与德治的辩证统一

法治既是一种治国方式和手段,也是人民行使管理国家、管理社会的权利的途径.德治的核心内容是要建立社会主义的道德体系和弘扬优秀的民族精神.法治和德治既有区别,又有联系,是辨证统一的.法治、德治的辩证统一是贯彻"三个代表"重要思想和建设中国特色社会主义的内在要求.     

Penetration of hardwoods by liquids

Summary Oven dry highly evacuated sticks of the sapwood of various hardwoods, 40 cm long by 1.0 to 1.2 cm in the radial and tangential directions, took up water to the extent of 44 to 82% of saturation by capillary flow in one minute. Heartwood sticks took up 15 to 38% of saturation in one minute. The initial rapid penetration was followed by a penetration in which the take up increase directly with the square root of elapsed time. In this range, the slope of toluene take up plots was about twice that of the water take up. This is close to the theoratical value on the basis of viscous flow control. The linear portion of the plots is followed by a curvilinear decrease in rate of take up to a final equilibrium value. Water take ups approached 100% of the theoretical values.Times to 0.99 of theoretical filling with water varied from 9 minutes for tupelo gum sapwood to 14.6 to 17.3 days for white oak heartwood. Complete filling with toluene was never attained. Diffuse porous hardwoods filled to the extent of 93.5 to 96.5% of saturation. Ring porous oaks filled to the extent of 88 to 92%, the lower values being for heartwood. Edge coating of the sapwood of yellow poplar and yellow birch with epoxy glue reduced the rate of penetration only slightly. End coating reduced the rate to a higher degree. Moisture gradients in the fiber direction for tyloses-free hardwoods were negligible at various stages of penetration, indicating that filling of the vessels was practically instantaneous. White oak heartwood gave an initial longitudinal gradient followed by a negligible gradient, indicating that longitudinal penetration is primarily through the lumen of the fibers rather than continously through the vessels. Longitudinal penetration was calculated to be 31.5 times as deep as transverse penetration in 100 minutes and 33.3 times as deep in 25 minutes for white oak heartwood. The ratios are of the same order of magnitude as for Loblolly pine. In both cases the ratios are smaller than values calculated from the fiber dimensions alone as ray cell penetration and cross grain effects tend to lower the ratios.Paper No. 3947 of the Journal Series of North Carolina State University Agricultural Experiment Station, Raleigh, N. C.     

Indentation of wood by wedges

Summary The deformation processes involved in wedge indentation of wood are described. The behaviour of wood is compared to that of an elastic-plastic solid and that of a cellular body. It approximates towards the former when its density is high and towards the latter when its density is low. The hardness of wood is examined as a function of density and of wedge angle.We wish to thank the University Grants Committee and the New Zealand Forest Service for supporting this work     

Suppression of debris movement by forests and damage to forests by debris deposition

 Forest buffer zones have recently been introduced in an attempt to suppress debris movement caused by mass wasting. There are, however, many questions left unsolved regarding the role of forests in suppressing debris movement and damage to forests by debris deposition. A number of debris avalanches occurred in southern Fukushima Prefecture and Hiroshima Prefecture in August 1998 and June 1999, respectively. Suppression of debris movement by forests and damage to forests by debris deposition were investigated in this study using aerial photographic interpretation and topographic analysis. Of the debris avalanches delineated in the Fukushima and Hiroshima areas, 282 and 84 sites, respectively, were forested, and 43 and seven sites, respectively, were nonforested. Topographic parameters, land use, and forest type at each site were surveyed by aerial photographic interpretation and topographic analysis. Suppression of debris movement by forest vegetation was confirmed by higher equivalent coefficients of friction and shorter average deposition zone length (about 28% and 55% shorter in the Fukushima and Hiroshima areas, respectively) in forested sites compared with nonforested sites. While previous studies suggested that the width of the forest zone required to prevent sediment outflow by surface erosion increases with increasing slope gradient, no clear relationship was found in this study. While the length of deposition zone of debris material (this study) is strongly affected by the dynamic solid friction coefficient and fluid friction of debris material, the length of deposition zone of the outflow of surface wash (past studies) is mainly affected by the tractive force of water flow. Among the 65 trees that remained at the terminus of deposition zones at five sites, 36 were alive and 29 were dead. Damage to the forest increases with increasing thickness of deposits and decreases with increasing tree diameter. Such results are useful for designing forest buffer zones. Received: June 18, 2001 / Accepted: August 21, 2002 Correspondence to:Y. Ishikawa     

Inhibition by pulp juice and enhancement by ingestion on germination of bird-dispersedPrunus seeds

To evaluate what prevents seed germination and why ingestion by birds enhances germination, we carried out germination experiments using bird-dispersed seeds of twoPrunus species (Prunus sargentii andP. ssiori) in the laboratory. Germination of seeds with following four treatments was compared: “Ingested seeds” excreted after feeding of fruits to birds; “Extracted seeds” deliberately extracted from the fruit pulp; “Juiced seeds” which were supplemented with the juice of the pulp after seeds had been deliberately extracted from the pulp; and “Intact seeds” in untreated whole fruits. Many ingested (27%, 23% inP. sargentii, 18% inP. ssiori) and extracted seeds (24% inP. sargentii, 17% inP. ssiori) germinated, and difference in germination percentages between ingested and extracted seeds were not significant, for eitherPrunus species. The Juiced seeds rarely germinated (2% inP. sargentii, 6% inP. ssiori), and seeds within intact fruits did not germinate. These results suggest that the fruit pulp and the juice of the pulp inhibit germination and the seeds could germinate without ingestion by birds once they had been manually extracted from pulp. Therefore, it is considered that bird ingestion enahnces germination by removing pulp, especially juice of the pulp, in these twoPrunus species.     

Deviations of kerf by handsaws III: the bend of saw blade by unsymmetrical set

To clarify the inducing mechanism of kerf deviation caused by unsymmetrical set of the handsaw, we hypothesized that the moment on the bottom edge of the saw blade, which is generated by the unsymmetrical set on handsaw teeth, bends the saw blade and this deformation should be one factor of the kerf deviation. To verify this hypothesis, the bend of a saw blade was examined by experiment and by calculation. In the experiments, a model tooth was attached to an actual handsaw. In the calculations, a saw model with a rectangular prism as the model tooth was analyzed by the finite element method. Loads were applied on the model tooth or the rectangular prism. From both the experiments and the calculations, the following results were obtained: (1) the deformation of the handsaw was caused by the unsymmetrical set in the length direction and the height direction of the saw blade; (2) the deformation and the inclination of the blade was larger at the front part of the saw than at the butt part; and (3) comparing the saw handle fixing conditions, the kerf deviation in the sawing line was supposed to be larger in the free handle condition and that kerf deviation in the depth direction was larger in the fixed handle condition. Based on the above results, it is apparent that one of the kerf deviation mechanisms originated from unsymmetrical set on the saw teeth. Part of this report was presented at the 54th Annual Meeting of the Japan Wood Research Society, Sapporo, Japan, August 2004.     

Quantification by allometric equations of carbon sequestered by Tectona grandis in different agroforestry systems

Non destructive methods for quantification of carbon seques-tration in tropical trees are inadequately developed. We described a stan-dardized method for estimating carbon stock in teak (Tectona grandi...     

Surface checking of wood is increased by photodegradation caused by ultraviolet and visible light

The aim of this research was to test the hypothesis that exposure to solar radiation increases the checking of wood exposed to the weather, and to examine the causes and spectral dependency of such an effect. Lodgepole pine decking samples were exposed outdoors under filters, which blocked selected regions of the solar spectrum while allowing other weathering factors to act on samples. Surface checking in samples was quantified after 12, 24 and 36 weeks of exposure, and the chemical and micro-structural changes occurring at weathered wood surfaces were examined. Check numbers and dimensions were greater in samples exposed under a filter to the full solar spectrum than in samples exposed under filters that blocked the transmission of UV, visible or infrared radiation. Samples that were shielded from more energetic wavelengths developed less checking and also showed less delignification at the exposed wood surfaces. Checks developed at the margins of rays and propagated at the interface between adjacent tracheids, close to the middle lamella. We conclude that exposure to UV and visible light increases the tendency of wood to check during exterior exposure. Our findings point to a link between changes in cell micro-structure as a result of photodegradation of lignin and the development of visible checks in wood exposed outdoors.