Cooperation effects of GA3, IAA and uniconazole-P on tension wood formation and gravitropism in Fraxinus mandshurica seedlings

The cooperation effects of GA3, IAA and uniconazole-P were studied on the gravitropism and wood formation in Fraxinus mandshurica Rupr. var.japonica Maxim. Seedlings using traditional paraffin section technology. Our results are： （1） Gravitropism of stems was strongly inhibited only in B, whereas promoted significantly in D, E, F, H and I treatments; （2） Xylem formation was increased on both sides in H, I and J treatments and on the lower side in E and F which also show the synergistic effect; （3） On the radial direction, cell wall thickness was enhanced on the upper side, whereas decreased on the lower side in C, and was also significantly promoted on the upper in E, G, H, I and J treatments. On the tangential direction, cell wall thickness was increased on the lower side in E, H, I and J treatments respectively; （4） Gelatinous layer of wood fibers was observed on the upper side in all treatments. These results suggest that both GA3 and IAA affected negative gravitropism and wood formation significantly. However, appliedor unapplited-uniconazole-P does not affect G-layer formation, indicating GA does not play the key role on G-layer formation, and ratio of GA3/IAA or IAA may be more important in regulating G-layer formation.

Regulation of applied-hormones on tension wood formation in Fraxinus mandshurica Rupr. var.japonica Maxim. seedlings gravitational response

We investigated the role of GA3, uniconazole-P and IAA on tension wood formation, in particular the vessel features, in Fraxinu smandshurica seedlings. Ninety seedlings were used and treated with applications of GA3 and/or IAA to the apical bud of the stem using a micropipette. Applications of GA3 or GA3 plus IAA with uniconazole-P strongly increased cell number of tension wood in comparison to that of no-uniconazole-P-applied, indicated that GA3 is more efficient than IAA on xylem cell production. Wood quality was also regulated by relative concentration ratio of GA3 to lAA, because of the vessel elements differentiation, density and size were controlled by GA3 and/or IAA on the different levels. These results suggested that the relative concentration ratio of GA3 to IAA and interactions of them are essential in regulating both wood quality and wood quantity, and tension wood formation in this species.

Spatial distribution of fine roots of larch and ash in the mixed plantation stand

The spatial distribution of standing fine roots in tree rows of different species in a 12-year-old mixed stand of ash (Fraxinus mandshurica Rupr.) and larch (Larix olgensis Henry) was studied by soil core sampling in early spring, 2001. It is found that ash and larch differ greatly in their belowground biomass distribution. Ash has much higher fine root biomass density in the soil than larch at stand level (with the max value of 4442.3 vs. 2234.9 gm-3). Both tree species deployed more fine roots in their neighboring zone, suggesting a less intensive competition between roots of the two species. Both fine root biomass density and root length density of ash in the zone between larch tree rows are greater than that of larch in zone between ash tree rows, indicating that ash is more powerful than larch in belowground competition. The spatial distribution feature of roots favors the growth of ash in the mixed stand.

Control of Negative Gravitropism and Tension Wood Formation by Gibberellic Acid and Indole Acetic Acid in Fraxinus mandshurica Rupr. var. japonica Maxim Seedlings

In the present study, we Investigated the role of glbberelllc acid （GA3） and Indole acetic acid （IAA） In the gravity response of stems and tension wood formation using two-year-old stems of Fraxinus mandshurica Rupr. var. Japonica Maxim seedlings. Forty-five seedlings were used and divided Into nine groups that Included five seedlings In each group. Seedlings were treated with applications of GA3 alone at concentrations of 2.89×10^-8 and 2.89×10^-7 μmol/L, IAA alone at concentrations of 5.71×10^-8 and 5.71×10^-7 μmol/L, or their combination to the apical bud of the stem using a mlcroplpette. Seedlings were positioned horizontally after the first treatment. The same treatments were repeated six times per week. At the end of the experiment, all seedlings were harvested. Then, stem segments were cut under a light microscope. Application of exogenous GA3 at the higher concentration stimulated the upward bending of stems, whereas exogenous IAA had no effect. A synergistic effect of GA3 and IAA on upward stem bending was observed following application of the two combinations of GA3 and IAA. Moreover, application of exogenous GA3 at the higher dose stimulated wood formation on both the upper and lower sides of the stems, whereas the mixture of GA3 and IAA had a synerglstic effect on wood formation In horizontal stems. Application of exogenous IAA alone at the lower concentration （5.71×10^-8 μmol/L） or application of a mixture of the higher concentrations of GA3 （2.89×10^-7 μmol/L） and IAA （5.71×10^-7 μmol/L） Inhibited the development of gelatinous fibers （the G-layer） of tension wood on the upper side of the horizontal stems. The differentiation of gelatinous fibers of tension wood was not Inhibited by GA3 when It was applied alone, whereas the development of the gelatinous fibers of tension wood was strongly affected by the application of IAA. The findings of the present study suggest that the development of the G-layer Is not related to the dose of GA3, but needs a relatively lower concentration of IAA.

Role of GA_3,GA_4 and Uniconazole-P in Controlling Gravitropism and Tension Wood Formation in Fraxinus mandshurica Rupr. var. japonica Maxim. Seedlings

GA3 and GA4 （gibberellins） play an important role in controlling gravitropism and tension wood formation in woody angiosperms. In order to improve our understanding of the role of GA3 and GA4 on xylem cell formation and the G-layer, we studied the effect of GA3 and GA4 and uniconazole-P, which is an inhibitor of GA biosynthesis, on tension wood formation by gravity in Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings. Forty seedlings were divided into two groups; one group was placed upright and the other tilted. Each group was further divided into four sub-groups subjected to the following treatments： 3.43 x 10-9 lunol acetone as control, 5.78 x 10-8 lunol gibberellic acid （GA3）, 6.21 x 10-8 lunol GA4, and 6.86 x 10-8 lunol uniconazole-P. During the experimental period, GAs-treated seedlings exhibited negative gravitropism, whereas application of uniconazole-P inhibited negative gravitropic stem bending. GA3 and GA4 promoted wood fibers that possessed a gelatinous layer on the upper side, whereas uniconazole-P inhibited wood formation but did not inhibit the differentiation of the gelatinous layer in wood fibers on the upper side. These results suggest that： （i） both the formation of gelatinous fibers and the quantity of xylem production are important for the negative gravitropism in horizontally-positioned seedlings; （ii） GA3 and GA4 affect wood production more than differentiation of the gelatinous layer in wood fibers; G-layer development may be regulated by other hormones via the indirect-role of GA3 and GA4 in horizontally-positioned F. mandshurica seedlings rather than the direct effect of GAs; and （iii） the mechanism for upward wood stem bending is different to the newly developed shoot bending in reaction to gravity in this species.

Ethylene Evolution Changes in Tilted Fraxinus mandshurica Rupr. var. japonica Maxim.Seedlings in Relation to Tension Wood Formation

The effects of ethylene on tension wood formation were studied in 3-year-old Fraxinus mandshurica Rupr. var. japonica Maxim. seedlings in two separate experiments. In experiment 1, ethylene evolution of buds and stems was measured using gas chromatography after 0, 2, 4, 7, 14, and 21 d of treatment; in experiment 2, both aminoethoxyvinylglycine （AVG） and AgNO3 were applied to the horizontally-placed stems, and the cell numbers on sites of applications were measured after 40 d. Ethylene evolution from buds was found to be much greater in tilted seedlings than in upright ones. The cell numbers of wood fibers in shoots and 1-year-old stems were reduced in treatments with 12.5×10^-7μmol/L AVG, 12.5×10^-8μmol/L AVG, and 11.8×10^-8μmol/Lmol/L AgNO3; whereas the horizontal and vertical diameters were reduced by treatment of 12.5×10^-7μmol/L AVG. Ethylene evolutions of shoots and 1-year-old stems were inhibited greatly in comparison with the control by applying 12.5×10^-7μmol/L AVG. The formation of a gelatinous layer of wood fibers was affected by neither AVG nor AgNO3 application. These results suggest that ethylene regulates the quantity of wood production, but does not affect G-layer formation in F. mandshurica Rupr. var.japonica Maxim. seedlings.

高温热处理对水曲柳材色的影响

The color change of ash wood(Fraxinus mandshurica)before and after high temperature heat treatment were investigated with WSC-S color difference meter in this paper.The results showed that:the color of treated wood is affected by the processing temperature,the higher the temperature,the darker the appearance,moreover,the change in L component can be used for quantitative analysis on color change.The color of treated ash wood by suitable processing temperature could be simulated to some valuable wood,for example,teak wood,some rosewood species,etc.The color of treated wood could be well replicated from laboratory scale experiments to commercial scale production.

热处理对消除水曲柳木材弯曲变形的影响

弯曲木制品的形状和尺寸稳定性直接影响弯曲木的应用前景和产品质量,为了保证弯曲制品的产品质量,笔者对弯曲木尺寸形状稳定性进行了研究。提出了弯曲木制品尺寸稳定性的相关理论以及如何提高弯曲木尺寸稳定性的方法。对弯曲木制品进行了不同温度处理下的曲率半径回复试验,比较了木材经100,140,160,180和200℃5种不同温度下分别处理2,4,8h后,再经24℃水浸泡24h,60℃水浸泡4h,100℃沸水煮1h后的曲率半径回复率。结果表明:弯曲木的曲率半径回复率随热处理时间的增加而减小,随处理温度的提高而减小。

柳蝙蛾危害对水曲柳木材性质的影响

采集同一立地条件柳蝙蛾危害的幼龄水曲柳,将其木材分4组：健康株、危害1a化学防治后愈合株、柳蝙蛾危害1a未防治株、危害3a以上的水曲柳。对危害部位进行解剖学、物理学实验,结果表明：柳蝙蛾对水曲柳木材的密度、硬度、胞壁率、年轮宽、纤维长度几个指标均有不同程度的影响。化学防治后1a密度这一指标恢复正常水曲柳的密度；年轮宽在被害后第三年才能恢复；对硬度的影响在以后的3a仍十分明显,纤维长度同硬度影响相近。

185℃高温热处理对水曲柳木材力学性能的影响

对经过185℃生产性高温热处理的水曲柳木材的力学性能进行测试和分析。结果表明:与素材一样,处理材弦径向弹性模量之间没有显著差异;高温热处理对水曲柳木材弦向弯曲强度和横纹抗压强度有不利影响,而弦向弹性模量、顺纹抗压强度、表面硬度等受此种工艺的影响很小。若将处理材与素材在实际使用情况下的力学性能进行比较,处理材除了在弦向弯曲强度上仍比素材低,上述各项力学性能均高于素材。

185℃高温热处理对水曲柳木材物理性能的影响

对经过185℃生产性高温热处理的水曲柳木材的物理性能指标进行了测定,并以素材为对照,对其密度、吸湿性和尺寸稳定性进行了分析。结果表明,处理材的绝干与气干密度相对素材略有下降,吸湿性则明显低于素材,且与素材之间的平衡含水率差值随相对湿度增大而增大,而在温度60℃、相对湿度分别为40%(干燥)、80%(潮湿)的环境中平衡后,处理材的弦、径向湿涨率相对素材均有不同程度的下降,两种环境下处理材的体积抗涨率分别达到了55.53%、47.34%,尺寸稳定性得到显著改善。

水热-微波处理水曲柳顺纹压缩应力-应变本构关系

通过对水热-微波联合处理的水曲柳幼龄材和成熟材顺纹压缩过程中应力-应变关系和木材化学组分变化的分析,建立木材顺纹压缩应力-应变本构关系。结果表明:在水曲柳顺纹压缩的初始阶段,应力-应变符合线性的弹性虎克定律;在弹塑性阶段,也基本符合线性的力学关系,建立的水曲柳幼龄材和成熟材顺纹压缩应力-应变本构关系由常数项(比例极限应力)和应力-应变线性关系表达式两部分构成;相同顺纹压缩率下幼龄材弹性模量和应力大于成熟材,主要受到木材化学组分差异的影响。

赤霉素对水平放置水曲柳幼苗的负向重性和木材形成的影响

对水平放置 2年生水曲柳 (Franxinusmandshurica)幼苗应用赤霉素 (GAs)及其合成抑制剂烯唑 (Uni . P)对幼苗的负向重性及木材形成中的生理作用进行了探讨。每种生长调节物质 10 0 μg溶于 5 0 %的丙酮中 ,每周 1次处理于幼苗顶端 ,连续处理 5周 ,并在第 1次处理后 2 4h ,将幼苗水平放置。在实验期间 ,对照及GAs处理幼苗茎负向重性受到了促进 ,而Uni . P处理则受到了抑制。GAs增加了茎上侧具有增厚细胞壁的胶质纤维细胞的数量。Uni . P抑制了茎上侧的木材形成 ,但没有影响胶质纤维的分化。对照区木质部中纤维素与木质素的比值上侧大于下侧。该比值在上侧GA4处理区大于GA3 处理区及对照区。该结果说明 ,胶质纤维的分化和木质部的增加对负向重性都是重要的 ;在该种中 ,赤霉素对于木质部细胞形成可能比对胶质纤维分化的影响更大。

水曲柳人工林凋落物分解及其N、P、K养分归还

采用埋袋法研究了水曲柳(17年生)两种不同来源凋落物(地下部分死亡的细根和地上部分落叶)的分解。结果表明,细根的年分解量为663.3kg.hm-2,占到凋落物年分解总量的29.5%。细根N、P、K养分归还量分别是凋落物总归还量的72.7%、34.5%、39.1%。由此可见,细根在林地C和养分循环中占重要地位。

间伐强度对水曲柳木材材质的影响

研究了不同间伐强度对水曲柳木材材质的影响 ,结果表明 :间伐强度对水曲柳木材的纤维长度和胞壁率无显著影响 ;对生长轮宽度、晚材率、生长轮密度、木材硬度有显著影响 ;材质综合评定表明重度间伐的林分木材材质最优 ,轻度间伐林分材质次之 ,未间伐林分材质相对较差 。

水曲柳落叶松人工幼龄混交林生长与种间竞争关系

在东北林业大学帽儿山实验林场.对10年生的水曲柳落叶松带状混交林及纯林进行了调查．结果表明：水曲柳在混交林中表现出明显增产,高生长比纯林增加12.1％～25.5％．胸径生长增加12.7％～32.3％.落叶松在混交林中也表现出增产的趋势．高生长比纯林增加4.1％．胸径生长增加12.5％.种间关系属双方有利.运用简单竞争指数对树种的竟争程度进行比较表明：在混交林中仅用地上部测树因子构造的简单竞争指数并不能很好地体现树种间地上和地下部的综合竞争程度，这种指数主要体现了树种间地上部竞争程度。

速生杉木为基材的水曲柳薄木贴面初步研究

以速生杉木为基材，水曲柳薄木为贴面材料，用脲醛树脂粘剂（UF）和聚醋酸乙烯醋乳液胶（PVAc）按一定比例混合后作为胶粘剂，热压贴面胶合，对温度和时间与巾面效果的关系进行了研究。结果表明：①用UF与PVAC比例混合的胶粘剂，在生杉木上进行水曲柳薄木贴面是可行的；②热压温度和时间对贴面效果的影响都是极显著的，并得到了一种较理想的薄木贴面热压工艺。

用有限元计算水曲柳裂纹尖端应力强度因子

该文研究了水曲柳（ＦｒａｘｉｎｕｓｍａｎｄｓｈｕｒｉｃａＲｕｐｒ．）发生Ｉ型断裂时裂纹尖端的应力场应力强度因子的情况．借助美国大型通用有限元分析软件ＮＡＳＴＲＡＮ计算出裂纹尖端附近的应力，并通过ＧＲＡＦＴＯＯＬ软件对数据进行后期处理，画出裂纹尖端附近的应力强度因子分布图．

水曲柳弯翘木皮恢复平直工艺

以3.4mm厚水曲柳弯翘木皮为研究对象,研究采用不同温度的湿空气和不同时间处理对弯翘木皮扭曲度恢复程度的影响。结果表明:在干湿球温差1℃情况下,当处理温度从70℃上升到100℃,温度越高,木皮扭曲度恢复效果越好,从1h延长到3h,处理时间越长,木皮扭曲度恢复效果也越好。结合实际生产需求,生产上较佳的工艺参数为:温度90℃、干湿球温差1℃、处理时间2h。

水曲柳人工林节子愈合与变色特征

节子的变色现象严重影响木材质量,了解节子变色规律及其影响因素是确定合理修枝的重要依据。以黑龙江省孟家岗林场地区49年生的水曲柳(Fraxinus mandshurica)人工林为研究对象,采用节子剖析技术分析自然整枝条件时水曲柳节子愈合时间与变色长度的变化规律。结果表明:水曲柳节子平均愈合时间约为6.7 a,约91.1%节子的愈合时间为3~11 a。水曲柳节子均出现了变色现象,平均变色长度约为30.93 mm,约92.2%节子的变色长度低于60.00 mm,仅有不足3.0%的节子变色长度超过80.00 mm。位于西南方向的节子愈合时间明显长于东北方向的节子(P<0.05),与东南、西北方向的节子愈合时间无显著差异(P>0.05)。位于树干高度10.0 m以下的节子愈合时间与变色长度均随节子着生高度的增加而逐渐增加(P<0.05)。节子愈合时间与变色长度均随着节子直径、死节半径的增加而增加,当节子直径超过15.00 mm,死节半径超过30.00 mm时,节子变色长度均明显增大。节子愈合时间越长,节子变色长度越大。水曲柳节子具有极易变色的特性,在生产上为了降低水曲柳节子变色长度,建议修枝时侧枝直径最好控制在15.00 mm内。