共查询到20条相似文献，搜索用时 312 毫秒
1.
1981年在黄岩县林科所首次发现木麻黄(Casuarina equisetifolia Forst)苗木溃疡病,1982年我们对台州地区玉环、温岭、黄岩、椒江、临海和三门等县(市)的木麻黄苗圃进行了普遍调查,同时对病害的症状、病原菌、发病条件和防治等方面进行了较为系统的研究。 相似文献
2.
3.
刺槐干腐病病原为樟疫霉菌(phytop-hthora cinnamomi),经土壤传播,伤口是病原侵染发病的先决条件.以往对自然界造成刺槐地下部伤口的原因未作系统研究,近两年我们作了一些观察,初步结果如下:一、病原菌接种试验1980年曾于赣榆、泗洪等县林间选择无病刺槐,分别在树干基部及根部进行刺伤、烫伤接种,证明伤口接种均可发病,无伤不发病.约80%以上的病斑发生在干基部表土层下.近期在淮阴县杨庄无病刺槐林,对表土层下根、基干的芽眼、皮层进行了接种保湿试验,结果病菌不侵染正常芽眼和皮层组织.芽眼经轻度刮伤可发病,皮层不发病;但刺伤接种均可发病,发病率达100%. 相似文献
4.
5.
6.
应用^32P和^86Rb对泡桐丛枝病病枝,叶吸收磷钾规律的研究 总被引：3，自引：0，他引：3
泡桐丛枝病在我国发生普遍,特别是在河南、山东和陕西关中地区危害严重,群众称之为泡桐的癌症。该病病原在1967年被日本人确定为类菌质体(MLO)。我国有不少人对这一病害作过研究,并取得了一定成绩。为了寻求更有效的防治措施,我们曾对该病进行了较为系统、全面的调查研究,对土壤中N、P、K含量的百分比值与感病指数间的关系,应用通径分析法进行研究,发现磷含量越高,发病越轻;钾含量越高,发病越重。经回归分析得知感病指数与P/K比值成反相关。在此基础上,对泡桐丛枝病病枝、叶对磷钾的吸收规律及不同种泡桐苗木吸收磷钾情况进行了同位素示踪试验。 相似文献
7.
苹果黑星病的发生规律与防治技术 总被引：2，自引：0，他引：2
苹果黑星病是国内检疫对象,在潍坊市个别县市已有零星发生。为了预防和控制该病的传播和蔓延,从1996年起,我们在发病果园对该病的发生规律及防治措施进行了调查研究。 相似文献
8.
黄栌,树形优美,适应性强,是园林绿化中不可缺少的优良树种。近年来,由于受白粉病的严重为害,早期大量落叶,影响观赏。1984～1986年,我们对黄栌白粉病进行了调查研究,基本上掌握了发病规律,找到了切实可行的防治措施。 相似文献
9.
1982年4～7月,我们对陕西、河南、甘肃、四川等省的18个县(市)的泡桐丛枝病发生情况与环境因子关系进行了调查,并对调查的土壤资料,用通径分析的方法进行了研究。结果发现土壤中磷、钾含量之比值(P/K)与泡桐丛枝病感病指数成负相关。即磷含量愈高,发病愈轻,含量愈低,发病愈重,钾的影响与此相反。这就为泡桐丛枝病的防治提供了新的途径。1965年以来,陕西省的渭南、蒲城等县,先后从河南引种了大量的兰考桐,使泡桐在陕西有了很大发展。随着泡桐的发展,丛枝病(MLO)也日益严重,给生产带来了很大威胁。目前,对泡桐丛枝病国内外都在研究,但对该病发病规律还不够了解。有的资料记载与土壤有关,但关系的焦点却不清楚。有 相似文献
10.
11.
用截头法栽植杨树防治溃疡病机理的研究 总被引：2，自引：0，他引：2
由Dothiorella gregaria Sacc.引起的杨树大斑型溃疡病在辽宁、河北和山西等省为害严重,它是影响造林成活率的主要因素之一。国内外许多学者一致肯定树皮含水量的增加能提高对皮部溃疡病的抗性。钟兆康曾认为,由Dothichiza populea Sacc.etBr.所致的杨树溃疡病的发生还与树干失水有关。我们的试验表明,由D.gregaria引起的大斑型溃疡病受木质部相对含水量的影响最大。因此使用截头法栽植杨树,对防治溃疡病、提高幼树成活率和生长量均有显著作用。这一结论已为大面积推广应用所证实。本文着重对这种栽植技术的防病机理是否与提高了树体含水量有关作进一步探讨。 相似文献
12.
Effects of trunk girdling on seasonal patterns of xylem water status, water transport and woody tissue metabolic properties were investigated in ponderosa pine (Pinus ponderosa Dougl. ex P. Laws.) trees. At the onset of summer, there was a sharp decrease in stomatal conductance (g(s)) in girdled trees followed by a full recovery after the first major rainfall in September. Eliminating the root as a carbohydrate sink by girdling induced a rapid reversible reduction in g(s). Respiratory potential (a laboratory measure of tissue-level respiration) increased above the girdle (branches and upper trunk) and decreased below the girdle (lower trunk and roots) relative to control trees during the growing season, but the effect was reversed after the first major rainfall. The increase in branch respiratory potential induced by girdling suggests that the decrease in g(s) was caused by the accumulation of carbohydrates above the girdle, which is consistent with an observed increase in leaf mass per area in the girdled trees. Trunk girdling did not affect native xylem embolism or xylem conductivity. Both treated and control trunks experienced loss of xylem conductivity ranging from 10% in spring to 30% in summer. Girdling reduced xylem growth and sapwood to leaf area ratio, which in turn reduced branch leaf specific conductivity (LSC). The girdling-induced reductions in g(s) and transpiration were associated with a decrease in leaf hydraulic conductance. Two years after girdling, when root-to-shoot phloem continuity had been restored, girdled trees had a reduced density of new wood, which increased xylem conductivity and whole-tree LSC, but also vulnerability to embolism. 相似文献
13.
Sap flux density was measured continuously during the 1999 and 2000 growing seasons by the heat dissipation method in natural Fagus crenata Blume (Japanese beech) forests growing between 550 and 1600 m on the northern slope of the Kagura Peak of the Naeba Mountains, Japan. Sap flux density decreased radially toward the inner xylem and the decrease was best expressed in relation to the number of annual rings from the cambium, or in relation to the relative depth between the cambium and the trunk center, rather than as a function of absolute depth. The relative influences of radiation, vapor pressure deficit and soil water on sap flux density during the growing season were similar for the outer and inner xylem, and at all sites. Measurements of soil water content and water potential at a depth of 0.25 m demonstrated that sap flux density responded similarly and sensitively to water potential changes in this soil layer, despite large differences in rooting depth at different elevations, localizing one important control point in the functioning of this forest ecosystem. Identification of the relative influences of radiation, vapor pressure deficit and drying of the upper soil layer on sap flux density provides a framework for in-depth analysis of the control of transpiration in Japanese beech forests. In addition, the finding that the same general controls are operating on sap flux density despite climate gradients and large differences in overall forest stand structure will enhance understanding of water use by forests along elevation gradients. 相似文献
14.
Xylem sap was collected from trunk segments of adult beech (Fagus sylvatica L.) trees by water displacement. Peroxidase activity was analyzed in xylem saps collected in different phases of the yearly growth cycle and from different heights up the trunks (up to 14 m). The xylem saps contained two major peroxidase isozymes with acidic isoelectric points of 4.1 and 4.6, respectively. Mean peroxidase activity was low during the emergence of the new leaves and high in summer and in winter. In the cold season, peroxidase activity decreased from the stem base to the top, whereas significant gradients were not observed during the vegetative period. 相似文献
15.
通过对杨树大苗、截干苗分别不同季节造林的效果调查,结果表明:秋季用杨树截干苗造林效果非常好,可明显提高造林成活率减少病虫害,降低造林成本。效果最不理想的是春季和秋季用全株苗造林。 相似文献
16.
During different phases of the annual growth cycle, xylem sap was collected from trunk segments of adult beech (Fagus sylvatica L.) trees by the water displacement technique. Irrespective of the height of the trunk, both sulfate and reduced sulfur compounds were detected in the xylem sap throughout the year. Sulfate was the predominant sulfur compound in all samples analyzed. Its concentration in the xylem sap varied between 10 and 350 micro mol l(-1), with highest concentrations in April, shortly before bud break. In contrast to other tree species, cysteine and not glutathione was the predominant thiol transported in the xylem sap of beech trees. The cysteine concentration ranged between 0.1 and 1 micro mol l(-1). As observed for sulfate, maximum cysteine concentrations were found in April. Apparently, both sulfate and cysteine transport contribute to the sulfur supply of the developing leaves. Seasonal changes in the axial distribution of cysteine and sulfate differed, indicating differences in the source-sink relations of these sulfur compounds. High, but uniform, xylem sap sulfate concentrations in April may originate from balanced sulfate uptake by the roots, whereas high cysteine concentrations in April, increasing with increasing height of the trunk, may originate in part from protein breakdown in the trunk. Reversal of the axial distribution of xylem sap cysteine in late summer-early fall to higher concentrations in the lower part of the trunk than in the upper part of the trunk suggests that the upper part of the trunk becomes a sink for cysteine as a result of the synthesis of storage proteins at this time of the year. 相似文献
17.
利用压力室技术测到的水势是缺乏修正的数值,比实际水势要高出许多,用该方法测定水势,只能反映出水势的大小变化,而不能用其代表木质部内真实的负压。蒸腾使木质部产生的负压最大不会超过-0．1Mpa,木质部内巨大负压的存在缺乏理论依据和直接的实验证据。空穴的必然发生使水柱无法保持连续,故连续水柱不存在。蒸腾状态下木质部水分的移动方式是自上而下分段依次移动的,这一现象与内聚力原理相抵触。蒸腾产生的负压能保持到蒸腾停止后继续使根系吸水。 相似文献
18.
林带对太湖地区农业非点源的控制效应研究 总被引：1，自引：0，他引：1
太湖地区是高度发达的农业生产区之一,大量使用化肥和杀虫剂加重该地区的环境污染水质污染。本研究选择以油菜-水稻和小麦-水稻为轮作方式的两片农田为农田生态系统,5年生的杨树林带和8年生的水杉林带为研究对象,通过采集水体、作物、林地下的氮和磷的样本,对农田生态系统中 N、P等(主要水污染物)迁移和淋失进行了研究,并对林带作对农业非点源污染的控制效应进行了分析。结果表明:农田生态系统中 N、P等迁移、淋失状况随轮作方式、作物种类及施肥状况而变化;农田与沟渠间的缓冲林带具有截留和净化土壤径流中的N、P等物质的作用,从而在一定程度上控制农业非点源污染。研究表明:当农田与林带宽度比例为100∶40时,在油菜-水稻轮作方式下,50.05%流失N和29.3% 的流失P可以被林带所吸收, 在小麦-水稻的轮作方式下,30.98 %流失N和86.73% P可以被林带所吸收;当农田与林带宽度比例为150∶40,在油菜-水稻轮作方式下, 33.7%流失N和19.58%P可以被林带吸收,在小麦-水稻的轮作方式下,20.65%流失N和57.82% 流失P可以被林带所吸收。因而,农田与林带宽度比例100∶40或150∶40较为合理,这种模型既能少占耕地,又能净化水质、保护生态环境。杨树生长快、用途广,适于太湖地区营造水环境保护林带。图2表4参8。 相似文献
19.
20.
Radial velocity profiles of water flow in trunks of Norway spruce and oak and the response of spruce to severing 总被引：1，自引：0，他引：1
Trunk-tissue heat balance, volumetric and staining methods were used to study xylem water flow rates and pathways in mature Norway spruce (Picea abies (L.) Karst.) and pedunculate oak (Quercus robur L.) trees. The radial profile of flow velocity was confirmed to be symmetrical in spruce, i.e., maximum flow velocity was in the center of the conducting xylem and tailed with low amplitude (about 30 cm h(-1)) in the direction of the cambium and heartwood. Variability around the trunk was high. In contrast, in oak, the radial profile of flow velocity was highly asymmetrical, reaching a peak of about 45 m h(-1) in the youngest growth ring and tailing centripetally for about 10 rings, but variability around the trunk was less, under non-limiting soil water conditions, than in spruce. In spruce, the flow rate increased abruptly within seconds when the tree was severed while immersed in water, and then decreased gradually, showing significant root resistance. We conclude that water flow through an absorbing cut surface differs from the flow higher in a tree trunk because of the presence of hydraulic capacitances in the conductive pathways. The staining technique always yielded higher estimates of flow velocity than the non-destructive tree-trunk heat balance method. 相似文献