关于杨树品种命名的探讨

本文着重叙述杨树品种分类命名及命名原则,杨树种以下分类单位的名称及命名方法,包含野生的天然杨树种,人工栽培种和人工杂交种。     

关于杨树引种工作方法的探讨

杨树是生长迅速、适应能力强、木材用途广及栽培繁殖技术比较容易的树种,是“绿化祖国”,加速祖国社会主义建设的优秀树种之一。目前,我国北方各省(区)、市林业及城市园林部门对杨树栽培都非常重视。为了寻求适应性强而速生优质的杨树,各地广泛开展了大规模的引种和选育工作。但因杨树种类很多,栽培历史较久,并已经选育出不少的人工杂种和自然杂种,目前已知全世界野生的自然种     

杨树黄叶病害对叶片光合和蒸腾作用的影响研究

本文以修武县杨树黄叶病为对象,研究了其光合蒸腾作用,结果表明:健康的杨树的光合作用、蒸腾速率和气孔导度均最高,其次是喷施FeSO4的杨树黄叶病株,未处理的病树3种指标最低,说明喷施FeSO4能显著提高杨树病株光合作用、蒸腾速率和气孔导度。     

杨树病死原因分析及应对措施

喀左县杨树人工纯林出现大面积病死现象,2012~2015年通过对杨树人工林调查,参考近几年的气象资料进行分析,阐述了杨树死亡现象发生的基本情况;分析了主要原因为气候因素、杨树品种因素、栽培管理因素和病虫害因素4个方面,这4种因素共同作用致使杨树人工林大面积死亡;并针对这些原因提出了应对措施。     

建昌县杨树病死原因调查分析及应对措施

建昌县杨树人工纯林出现大面积病死现象,2012年至2015年森防站通过对杨树人工林调查,参考近几年的气象资料进行分析,阐述了杨树病死现象发生的基本情况;分析了病死主要原因:有气候因素、杨树品种因素、栽培管理因素和病虫害因素4个方面,这4种因素共同作用致使杨树人工林大面积病死;并针对这些原因提出了应对措施。     

民勤绿洲防护林带作用下作物生长分析

本试验对比研究了小麦和玉米在枣树和杨树 2种农田防护林带作用下的生长状况和产量。结果表明 :枣树林带下的作物生长状况明显优于杨树林带。枣树林带下小麦的干物质积累速度高于杨树林带 51 4% ,致使生物产量相对杨树林带高 38 4%。不同种植方式小麦、玉米的粮食产量增加 4 2 %～ 13 0 %。增产的原因之一是枣树林带下作物不同生育期农田土壤含水率均高于杨树林带。可见枣树林带的胁地作用弱于杨树林带。推广枣树防护林 ,实现枣粮间作 ,是提高民勤绿洲农业产量的重要措施     

吉林市杨树病虫害种类调查

随着吉林市杨树速生丰产林栽植面积的逐年扩大,病虫危害日趋严重。2004—2007年对吉林市杨树的病虫害种类进行了调查。结果表明:吉林市杨树常见虫害种类56种,危害严重种类12种,常见病害种类17种,危害严重种类4种。     

杨树溃疡病的发生与防治

杨树溃疡病是杨树干枝病最主要的一种,过去以北方发生为主,近年在南方大面积发生,特别在新栽植的杨树林地发生严重。溃疡病主要有水泡型真菌性溃疡病、斑枯型真菌性溃疡病、烂皮型真菌性溃疡病和肿瘤型细菌性溃疡病4种。     

几种杀虫剂对杨树食叶害虫的防治效果评价

为筛选出防治杨树食叶害虫的高效低毒杀虫剂,降低食叶害虫危害,保障林业的健康可持续发展,试验选取0.5％苦参碱水剂、10％虫螨腈悬浮剂、25％灭幼脲悬浮剂和8％氯氰菊酯悬浮剂4种杀虫剂,在林间条件下,对比分析了4种杀虫剂对杨树食叶害虫的防治效果.结果表明,供试4种杀虫剂对杨树食叶害虫均有一定的防治效果,以0.5％苦参碱水...     

北方地区杨树不同营林模式对土壤理化性质的影响

为了筛选出适合在我国北方地区推广的杨树营林模式,选择了杨树纯林、杨树与刺槐混交、杨树与三七混种、杨树与花生混种4种营林模式进行比较试验,研究不同营林模式对杨树林分土壤理化性质的影响,结果表明:杨树纯林的土壤含水量最低,中砂、粗砂占比最高,说明杨树纯林可以加剧土壤的沙化,不利于提高土壤的蓄水能力;杨树与刺槐混交、杨树与花生混种、杨树与三七混种,相对于杨树纯林,土壤中的含水量有所提高,粗砂、中砂的占比降低,黏粒、细粉粒比例提高,以林药模式保持水土效果最佳,其次为农林模式。建议推广杨树与药材、杨树与农作物2种模式。     

Enlargement of individual cellulose microfibrils in transgenic poplars overexpressing xyloglucanase

Holocellulose samples prepared from transgenic poplars overexpressing xyloglucanase had crystal widths of 3.2–3.5 nm as a result of the (2 0 0) plane, based on their X-ray diffraction patterns, and crystal widths were greater than those of the wild type (3.0 nm). Cellulose microfibril widths in the holocellulose samples were further determined from transmission electron microscopic (TEM) images of individualized fibrils prepared by 2,2,6,6-tetramethylpiperidine-1-oxy radical-mediated oxidation of the holocelluloses and the successive disintegration of the oxidized products in water. The TEM images also supported the finding that cellulose microfibril widths of transgenic poplars were larger than those of the wild type. The cellulose microfibril widths of transgenic poplars were approximately 6 nm, whereas those of the wild type were about 5 nm. However, such enlargement of cellulose microfibril widths could not be explained by the increased cellulose contents of the transgenic poplars alone.     

Biosafety assessment of transgenic poplars overexpressing xyloglucanase (AaXEG2) prior to field trials

We performed biosafety assessments of transgenic poplars prior to field trials. Constitutive expression of the Aspergillus aculeatus xyloglucanase in Populus alba increased the cellulose content and specific gravity of its stem, the leaves of which were visibly greener, thicker, and smaller than those of the wild-type plant. Although the young transgenic poplars grew faster than the wild type in a growth chamber, there was no distinguishable difference in growth between the poplars when they were placed in a special screened greenhouse. Allelopathic tests showed that the transgenic poplars do not produce harmful substances. Based on all the biosafety assessments and the scientific literature on poplar species, we came to the conclusion that transgenic poplars probably do not disturb the biological diversity of the surrounding environment, even when they are submitted to field trials.     

Analyses of leaves from open field-grown transgenic poplars overexpressing xyloglucanase

The transgenic expression of Aspergillus xyloglucanase cDNA (AaXEG2) with 35S promoter in the leaves of open field-grown poplars was studied. The level of xyloglucan in the transgenic poplars was decreased to 15–16% in the non-fertile soil (forest-field soil) and to 21–22% in the fertile soil (farming-field soil) compared with that of the wild-type poplars. The leaves exhibited a smaller surface area with more rounded teeth than those of the wild-type plants, similar to the sun leaf variety that was grown in the incubation room and subsequently greenhoused. The majority of total veins with water-conducting vascular bundles were shorter in the leaves of the transgenic poplars than those of the wild type. This decrease in vein length may result from a decrease in xyloglucan during leaf development, from which large numbers of proteins were markedly downregulated in the leaves of the transgenic plants via proteomic analysis. It seems likely that the leaves of the transgenic poplars came to relax the edges of their tooth rather than extend their veins as a result of the loosening of the xyloglucan cellulose networks in the leaves.     

Growth and root sucker ability of field-grown transgenic poplars overexpressing xyloglucanase

Xyloglucan is thought to be a key hemicellulose cross-linking adjacent cellulose microfibrils in plant cell walls. The growth traits of transgenic poplars (Populus alba) with decreased xyloglucan from overexpression of Aspergillus aculeatus xyloglucanase were characterized during a 4-year field trial. The field-trial site consisted of two blocks, a fertile soil block and a non-fertile soil block, determined by soil analysis. In the fertile block, the growth of aboveground biomass of the transgenic poplars was reduced to 24?C44?% compared to that of wild-type poplars, in contrast to the growth seen in chamber and greenhouse conditions. In the non-fertile block, the aboveground biomass of transgenic poplars was also smaller than that of the wild-type poplars. Because poplars reproduce asexually by root suckers, we also compared the formation of root suckers from transgenic and wild-type poplars. Root suckers formed less frequently from transgenic poplars than from wild-type poplars. The growth rates of root suckers from transgenic poplars were also slower than those from wild-type poplars. The results showed that constitutive degradation of xyloglucan impairs poplar growth and vegetative reproduction ability.     

杨树烂皮病对湖北地区杨树的危害风险

杨树烂皮病是湖北地区近年来危害性上升迅速的林业有害生物,其主要寄主在湖北种植广泛。其病原金黄壳囊孢菌Cytospora chrysosperm侵染杨树枝干部,从而导致死亡。依据林业有害生物风险分析指标体系,采用多指标综合评价法对杨树烂皮病危险性进行定量化分析和评判。结果表明,杨树烂皮病在湖北省的危害风险值为2.01,即:杨树烂皮病在湖北地区为中度危险性的林业有害生物。此结果将为我省应杨树烂皮病的综合防控技术研究提供基础科学依据。     

转玉米PEPC基因杨树的光合生理特性分析

以转PEPC基因南林895杨和对照(南林895杨)为材料,分析不同转基因植株的光合生理参数。结果显示:转PEPC基因杨树与C4光合途径相关的酶活性比对照增高,PEPC活性增加较为明显,最高达38.6%。转PEPC基因杨树表现较强的对强光利用能力,其光饱和点比对照提高约10%～20%,饱和点时的光合速率比对照高17.7%～58.1%。转PEPC基因杨树光补偿点低于对照,利用弱光的能力增强;CO2饱和点低,比对照低22.2%～44.4%;CO2补偿点也较低,比对照降低58.1%～76.5%,表明对CO2的利用效率较高。此外,转基因杨树羧化效率增高,比对照增加最高达62.3%。     

表达豇豆胰蛋白酶抑制剂转基因杨树的蛋白检测

对转豇豆胰蛋白酶抑制剂基因的三倍体毛白杨杂种 [(毛新杨×毛白杨 )×毛白杨 ]的可溶性总蛋白和胰蛋白酶抑制剂蛋白的含量进行测定 .结果发现 ,与未转基因植株相比 ,所有供试转基因株系叶片中的总可溶性蛋白含量明显增加 ,但老叶的含量高于嫩叶 ,这表明转基因株系可溶性总蛋白含量增加可能是CpTI基因表达的结果或由于外源基因导入后引起杨树基因组中某些自身基因的表达所致 .转基因株系叶片中有较高含量CpTI,而对照叶片则检测不到CpTI,这进一步证实了CpTI基因已在转基因株系中得到稳定表达 .进一步比较发现 ,在供试的 5个无性系中 ,TG0 7、TG0 4和TG71在总蛋白含量和CpTI含量增加较为明显 .另外 ,聚丙烯酰胺凝胶电泳胶分析发现 ,与未转基因植株相比 ,在所有供试转基因株系叶片中均出现一条分子量为 11.3kD的清晰蛋白带     

新疆杨死亡情况调查及原因分析

通过对阿拉尔地区新疆杨枯死林分的调查，认为新疆杨枯死的主要原因是近年来在国内发现的1种新害虫——克里角梢小蠹Trypophloeus klimeschi Eggers成虫、幼虫危害所致。同时，对其发生危害情况进行了初步观察，为今后进一步制定防范措施提供了依据。     

杨树红心病危害的调查研究

杨树红心病是分布广泛、危害严重的一种病害,几乎所有杨树品种都会遭侵染,成年树病株率达100%,变色比率15.65%~50.70%。从当年生扦插苗到成年树均能发生,红心病主要发生在主干的髓心和木质部。该病的严重程度与栽植的立地条件有关,在低洼湿地栽植的杨树其变色程度严重,且随树龄的增加而加剧,生长速度快的杨树,危害程度大。杨树品种不同,危害程度不同,品种之间存在着显著差异。     

转基因杨树对杨小舟蛾幼虫解毒酶活性的影响

用转Bt单基因和转Bt CpTI双价基因杨树叶片饲喂杨小舟蛾,幼虫中肠酯酶的活力在饲喂初期显著升高,但在饲喂一定时间后受到抑制:转Bt单基因杨树在饲喂24 h开始受到抑制,48 h受到明显抑制,较对照下降了15.8%;而转双价基因杨树在饲喂12 h受到明显抑制,较对照下降了38.1%.转双价基因杨树对中肠酯酶的抑制作用大于转Bt单基因杨树.转Bt单基因杨树对幼虫中肠羧酸酯酶的抑制能力不强,而转双价基因杨树对中肠羧酸酯酶的抑制作用大于转Bt单基因杨树,饲喂12 h后活力开始受到抑制,饲喂24、36、48 h的活力分别较对照下降了33.4%、22.5%、29.6%,与对照均有显著差异.转基因杨树主要通过抑制幼虫中肠酯酶和羧酸酯酶这2种解毒酶活性而干扰昆虫正常的生理代谢,从而起到毒杀害虫的作用.