【作者】 陈超燕；

【导师】 束庆龙；

【作者基本信息】 安徽农业大学 ， 森林保护， 2005， 硕士

【摘要】 樟树(Cinnamomum camphora (L) Presl )[1]是一种常见的行道树。黄化病是当前城市樟树最常见的病害。本文通过樟树黄化病发生原因的调查和病株的生理指标、生化指标以及叶片结构等因素分析研究,初步找出了樟树黄化病发生的主要原因和致病机理,研究成果为该病今后的进一步研究和科学防治提供了理论依据。 调查研究表明:影响樟树黄化的原因是多方面的,不同城市、不同街道、甚至同一街道不同植株间,黄化发生原因可能各不相同,但主要原因是由于立地条件不良造成的,黄化病属于非侵染性病害,发生原因主要有以下一些因素——根际周围水泥严密覆盖;土壤遭受建筑污染或生活污水毒害;土壤 pH 值过高;土壤粘重板结、质地不良;排水不畅、局部积水等。在城市环境中,几乎所有的樟树根际周围均在不同程度上被水泥(路)覆盖。樟树黄化程度与地表覆盖面积之间呈明显的正相关,即地表覆盖的愈严密,黄化程度愈重;全部被水泥覆盖的植株,植株多处于濒危状态、甚至逐步枯萎死亡。此外,在没有水泥覆盖的地块,地表由于人为活动频繁而导致土层板结,土壤容重较大,也不利于林木的生长而发生黄化现象。 土壤污染对病害的影响极大。目前合肥土壤污染有三种来源:一是建筑污染,主要发生在树木栽植之前,修路或建房等工程所留下的水泥、石块、粉煤灰、石灰等;二是机动车修理部等所排出的机油造成对周围土壤污染和树木根系毒害;三是工业和生活污水所造成的土壤污染,如化工厂、酒店食堂、生活区水沟旁、洗衣房等场所排放的脏水对土壤的污染。 土壤 pH 值过高是黄化的最直接原因。在自然状态下,合肥地区的土壤 pH 在5.5-6.5 之间,但城市土壤由于遭受建筑或其他垃圾的污染,多数樟树生长地段的 PH均在 8.1—8.9 之间,呈显著的碱性反应。在这样的土壤环境下,土壤中的铁元素不能正常地被植物吸收利用,使植物叶片处于缺铁状态而呈现黄化症状。 土壤质地不良也是引起樟树黄化的原因之一。在土壤调查中发现,樟树栽植穴内几乎看不到有正常的土壤存在,大多数表层土壤均在施工中被移走,遗留下来都是一些粘重板结、肥力较低、不适合树木生长的心土。 土壤肥力如有机质含量、氮、磷、钾、铜、铁、镁、锌、锰等矿质元素的含量与感病指数之间有明显的相关性。所调查的土壤由于受到各种各样、不同程度的污染或破坏,其营养元素的含量和比例均出现一些异常状况,不利于植物的正常生长发育,促进了黄化病的发生。 在所调查的范围内,树龄与发病率之间呈负相关关系。在合肥市,普遍现象是栽植不久的幼树一般发病比较严重,而树龄较大的树木发生黄化的现象较少,其原因可能与以往栽植的环境条件较好或大树根系发达,可以伸展到较远、较好的土壤中去吸更多还原

【Abstract】 The yellows of camphor-tree is a common and serious disease in Hefei and other cities. The disease can cause the yellows of leaf, decline of plant development, unusual of shape, even the death of the whole plant, and its ornamental value and ecological function were reduced greatly, In this thesis the causes and predisposing mechanism of camphor-tree yellows were studied, and the relationship between the disease and stand condition, soil fertility, physiological and biochemical characteristic were determined in order to find the good methods for control to the disease . The results of investigation indicate: there are many factors for the causes of camphor-tree yellows. The cause of disease varies with the different cities, different streets, even different plants in the same street. However, the key factors that disease occur are that the root is covered tightly with the cement; the soil is polluted by the building garbage or waste or the sewage; soil pH value is too high; the soil texture is too clay and harden which caused by activity of people, and sometimes poor drainage, etc. In the urban environment the coverage of the cement around the root of camphor tree play an important role in the disease. There is obvious positive correlation between degree of the yellows and the earth’s surface coverage of cement, namely the more tight the earth’s surface is covered, heavier is the degree of yellows. If totally covered by the cement the plant will be very dangerous, even the withered death progressively. In addition, there is no cement cover, the soil texture too harden because of the artificial activity such as park. All these conditions its soil is unfavorable to the growth of camphor tree and the yellows or other diseases will occur. The soil pollution is one of the most important factors affecting the disease. In Hefei city there are three kinds of sources of the soil pollution: (1). pollution from building: which existed already the trees are planted, such as cement, stone, ash, stone lime, brick etc. those were leaved by the project of the roads and building; (2). pollution from engine oil discharged: such as the departments for motor vehicle and all kinds of machines repaired, (3). pollution from the waste water or sewage: of industry: such as waste water of chemical factory and luncheonette, eating-house, laundry, etc. These pollution above-mentioned may cause that the soil was pollution and system of trees roots were poisoned; High soil pH value is a immediate cause of the camphor tee yellows. Soil pH of the area in Hefei is in 5.5-6 under the un-destroy or natural state; while most of the urban camphor trees grow among 8.1 and 9.1 because of suffering pollution of the building or other rubbish. Under the environment of alkaline reaction soil, iron element of soil can not be absorbed by plant normally and make the leaves of plant lacking the iron and yellowsing. The soil texture in urban conditions is too harden and clay, which is one of the reasons to yellows. We hardly see that there existed normal or undestroyed soil which was investigated, Almost every place in city proper the surface of the soil is removed when constrictor and the heart soil that do not suit trees growing were leaved. Soil fertility such as organic content, nitrogen, phosphorus, potassium, copper, iron, magnesium, zinc, manganese etc. have obvious correlation with the disease index. The soil investigated suffered pollution or destruction in various degree, and the content and proportion of nutrition element are unusual state in that it is unfavorable to growth of camphor tree. Within the range where has been investigated, the age of tree is negatively relation with index of yellows disease. In Hefei city, the disease of younger trees is more serious than older trees generally. The growth of tree which suffered disease reduced greatly. For example the length growth of two-year-old branch of disease trees is shorter than that of health trees, and the area of new leaf with disease is obviously diminished too. The photosynthetic更多还原