桉树无性系的单板出材率与价值研究     

任世奇  罗建中  彭彦  谢耀坚  卢万鸿  曹加光  姜英 《草业学报》2010,19(6):46-54

为了系统深入地对单板出材率和价值的影响因素进行研究,以11个6年生桉树无性系为材料,使用无损检测仪器Pilodyn和Fakopp测定立木的外部密度和应力波传输速度,用轴向生长应变仪器CIRAD-ForestMethod测定立木生长应力,结合对原木外观形质的检测和单板质量等级的划分,运用差异性分析、相关分析及多元逐步回归分析。结果表明,无性系间立木的材性性状,原木形质中的小头最小直径、弯曲度和端裂指数存在显著差异。节疤,尤其死节(孔洞)、裂缝是降低单板等级的主要因素。无性系间单板出材率和价值存在显著差异,其中出材率(%)从大到小排序为:GL₉(48.27),EC₃₄(47.17),LH₁(44.00),DH_32-22(42.00),GL₄(37.56),SH₇(34.88),UC_184-1(34.38),LH₅(31.06),M₁(29.74),DH_201-2(25.41),SG₁(16.28),最大是最小的2.97倍;单段原木价值(RMB/log)从高到低排序为:EC₃₄(13.37),GL₉(13.12),GL₄(12.36),LH₁(12.02),DH_32-22(11.55),LH₅(10.72),SH₇(9.22),UC_184-1(7.95),M₁(7.55),DH_201-2(5.97),SG₁(4.88),最高是最低的2.74倍;单位材积价值(RMB/m³)从高到低排序为:EC₃₄(856.49),LH₁(794.55),GL₉(788.68),DH_32-22(763.02),GL₄(681.44),SH₇(629.35),UC_184-1(597.66),LH₅(559.08),M₁(538.39),DH_201-2(450.49),SG₁(294.53),最高是最低的2.91倍。5个品种的无性系作为胶合板用材,尾巨桉无性系价值最高。原木弯曲度是影响单板出材率和价值的主要因素,木材密度、小头直径、应力波传输速度及端裂指数等对其也有显著影响。无损检测仪器Pilodyn和Fakopp可对单板出材率和单位材积价值进行粗略预测。  相似文献   

蒙脱土-DDAC复合防腐剂处理杨木的性能及表征     

汪亮  曹金珍  姜卸宏  刘如 《北京林业大学学报》2010,32(4):242-246

为了提高人工林杨木的力学性能和耐腐性,采用蒙脱土(MMT)-二癸基二甲基氯化铵(DDAC)复合防腐剂(ODP),通过满细胞法处理杨木试材,分析了防腐处理材的增重率、DDAC保持量、有机蒙脱土(OMMT)在木材内部的分布、横纹抗压强度和耐腐性。结果表明:OMMT的引入使试材增重率增加,DDAC保持量下降;OMMT绝大部分以颗粒存在于木材导管腔中,部分尺寸较小的颗粒和剥离片层可以通过纹孔,很难进入细胞壁;ODP处理材的横纹抗压强度比蒸馏水处理材提高了27%;相对于DDAC处理材,ODP处理材的耐腐性比单组分DDAC处理材好。  相似文献   

褐腐杨木微观结构、力学性能与化学成分的关系研究   总被引：2，自引：2，他引：0  

葛晓雯  王立海  侯捷建  荣宾宾  岳小泉  张盛明 《北京林业大学学报》2016,38(10):112-122

为了探究褐腐对阔叶材主要材性的影响规律,对杨木边材试件进行室内褐腐培养,为期12周,每周抽样分别测试健康和腐朽木材的微观结构、力学性能及化学成分,并分析其随褐腐程度的变化情况,研究力学性能和化学成分之间的关系。结果表明:随褐腐程度的加深,木材细胞腔内的菌丝越来越多,纹孔膜和纹孔边缘的细胞壁分别于质量损失率为10%、16%时出现开裂;质量损失率为24%时,细胞壁严重溃烂。褐腐培养时间和质量损失率都对力学性能影响极显著;冲击韧性和抗弯强度的损失率随褐腐程度呈对数函数变化趋势,抗弯弹性模量和顺纹抗压强度的损失率呈线性变化趋势。各力学指标对褐腐的响应速度以及受褐腐影响的程度均呈如下规律:冲击韧性抗弯强度抗弯弹性模量顺纹抗压强度。不同褐腐程度试样中的综纤维素、半纤维素以及抽出物含量差异极显著,纤维素和木质素差异不显著。腐朽过程中褐腐菌最先主要降解半纤维素,质量损失率为20%左右时,转为以分解纤维素为主。冲击韧性的快速显著降低与半纤维素的降解有关,抗弯强度的变化与综纤维素含量有关,抗弯弹性模量和顺纹抗压强度的线性降低是由纤维素的缓慢降解决定的。总之,在褐腐过程中,木材微观水平上化学成分的降解和细胞壁结构的破坏从根本上导致了宏观力学性能的降低。   相似文献   

一种两阶段彩色图像分割方法的原木识别     

李小林  景林  黄世国  黄习培 《福建农业大学学报(自然科学版)》2013,(5):548-551

针对原木图像存在年轮、锯痕以及原木之间紧密接触的问题,提出两阶段分割方法,即依据原木目标和背景的颜色差异应用K均值算法进行聚类得到相互紧密接触的原木目标分割结果;然后应用分水岭分割算法将粘连的原木目标加以分离．结果表明：与直接用分水岭算法和K均值算法相比,本方法能够有效地分割出原木目标．  相似文献   

小西葫芦绿斑驳花叶病毒生物学特性及传播方式     

梁智玲  刘美  亓芳芳  康保珊  古勤生  彭斌 《植物病理学报》2022,52(1):68-76

小西葫芦绿斑驳花叶病毒(Zucchini green mottle mosaic virus,ZGMMV)是我国新报道的侵染葫芦科作物的烟草花叶病毒属病毒.从感染病毒的葫芦叶片中分离出ZGMMV,摩擦接种西瓜(Citrullus lanatus)、葫芦(Lagenaria siceraria)、西葫芦(Cucurbit...  相似文献   

动态边界条件下一类强阻尼波动方程解的爆破     

李玉环  刘盈盈  穆春来 《西南大学学报(自然科学版)》2011,33(7)

考虑了一类具有Kelvin-Voigt阻尼的波动方程.运用位势井理论,通过构造稳定集和不稳定集,结合能量分析的方法,首先证明了当初值属于稳定集时,该问题存在整体解;其次证明了强阻尼项的存在使得问题的解一致趋近于零,且具有指数衰减速率;最后给出了解在有限时间爆破的充分必要条件.  相似文献   

Hydrothermic regime,dynamics of organic matter and nitrogen in drained peaty soils at different sanding modes     

F. R. Zaidelman  A. P. Shvarov 《Archives of Agronomy and Soil Science》2013,59(2):123-142

The rate of biochemical decomposition of organic matter in drained peaty soils has been studied for the black, sand‐mixed, and sand‐mantled farming systems with a concurrent analysis of hydrothermic conditions. The maximum depletion of peat was observed in the plow horizon for the black system and in the plow and subplow horizons for the mixed system. For the sand‐mantled system, two maximums were found for the biochemical decomposition of organic matter (in the plow horizon and in the zone of the open capillary fringe). Sand‐mixed and sand‐mantled cultures enhance the biochemical depletion of peat. An accelerated decomposition of the peat organic matter after addition of sand results in increasing the content of mobile nitrogen in soil and ground waters. Protection against the degradation is associated with control of the ground water table.  相似文献   

Wood density and carbon and nitrogen concentrations in deadwood of Chamaecyparis obtusa and Cryptomeria japonica     

Yoshimi Sakai  Shin Ugawa  Shigehiro Ishizuka  Masamichi Takahashi  Chisato Takenaka 《Soil Science and Plant Nutrition》2013,59(4):526-537

Estimating carbon (C) and nitrogen (N) stocks in deadwood in forests nationwide is required for understanding large-scale C and N cycling. To do so requires estimated values of wood density and C and N concentrations. Additionally, parameters that show variation should be examined. In this study, we clarified the estimated values and the variation in three parameters in each decay class of each of two tree species and examined whether dead log diameter and region contribute to variation in the parameters. Data were collected from 73 Chamaecyparis obtusa (Sieb. et Zucc.) Endl. plantations and 66 Cryptomeria japonica D. Don plantations throughout Japan. Wood densities decreased from 386 to 188?kg?m^?3 for C. obtusa and from 334 to 188?kg?m^?3 for C. japonica in decay classes 1–4. The variation in wood density increased with decay class, and the coefficient of variance increased from 13.9% to 46.4% for C. obtusa and from 15.2% to 48.1% for C. japonica. The N concentrations increased from 1.04 to 4.40?g?kg^?1 for C. obtusa and from 1.11 to 2.97?g?kg^?1 for C. japonica in decay classes 1–4. The variation in N concentration increased with decay class, and the coefficient of variance increased from 51.9% to 76.7% for C. obtusa and from 50.3% to 70.4% for C. japonica. Log diameter and region contributed to variations in wood density and N concentration in decay classes 1 and 2 for C. obtusa and C. japonica. However, no relationship was observed between regional climates and the two parameters. In contrast, C concentrations ranged from 507 to 535?g?kg^?1 and were stable with much lower coefficients of variance throughout the decay classes for both tree species. Thus, we recommend that the same C concentration can be adapted for all decay classes of both tree species.  相似文献   

Argentinian potato leafroll virus P0 protein: Novel activities for a previously known suppressor     

María P. Barrios Barón  Verónica C. Delfosse  Yamila C. Agrofoglio  Vanesa Nahirñak  Natalia I. Almasia  Cecilia Vazquez Rovere  Ana J. Distéfano 《Plant pathology》2021,70(2):259-274

The potato leafroll virus (PLRV) P0 protein (P0^PL) is a suppressor of RNA silencing. In this study, we showed that P0 protein from an Argentinian isolate of PLRV (P0^PL-Ar) has an additional activity not described for other PLRV or P0 proteins from poleroviruses. Besides reporting that P0^PL-Ar displays both local and systemic silencing suppressor activity, we demonstrated, for the first time, that P0^PL-Ar impedes accumulation of dsRNA-derived siRNAs. We also showed that P0^PL-Ar interacts with Solanum tuberosum SKP1 orthologue (StSKP1) and triggers destabilization of ARGONAUTE 1 (AGO1) and that these actions are mediated by the F-box-like domain. A mutant in the GW/WG motif within the P0^PL-Ar F-box-like motif lost the suppression activity, the interaction with StSKP1 and abolished AGO1 decay. Interestingly, a mutant in the L76/P77 residues within the P0^PL-Ar F-box-like motif, which lost the suppression activity and the interaction with StSKP1, retained the capacity to enable AGO1 decay. Thus, unlike other P0 proteins of previously characterized poleroviruses, P0^PL-Ar seems to have a dual activity, according to the findings of this study. This protein would act at both an upstream and a downstream step of the RNA silencing pathway: upstream of Dicer-like enzyme (DCL)-mediated primary siRNA production and downstream at the RNA-induced silencing complex (RISC) complex level. Our results contribute to the understanding of the different ways PLRV P0 proteins function as silencing suppressors.  相似文献   

Effect of applying nitrogen fertilizer to a potato seed crop on the susceptibility of the daughter plants toErwinia carotovora subsp.atroseptica     

Soile Prokkola 《Potato Research》1994,37(2):103-111

Summary Seed potatoes of cvs Record and Bintje were grown with 30, 80 or 130 kg N/ha. In the subsequent growing season the seed tubers, which were inoculated or not with two concentrations ofErwinia carotovora subsp.atroseptica (Eca), were subjected to the same fertilization treatment. The incidence of blackleg and the level of seed tuber decay increased from the uninoculated treatment to the higher inoculum level, but the degree varied considerably from one year to another. Cv. Bintje was more susceptible to blackleg and yield loss caused by Eca than cv. Record. In 1990, when disease incidence was high, the proportion of blackleg stems increased with increasing doses of nitrogen fertilizer which had been applied to the seed crop, but was not significantly affected in 1988 and 1992. Seed tuber decay was retarded by the lowest nitrogen dose. The yield of the subsequent crop was not affected by the nitrogen dose applied to the seed crop.  相似文献