【作者】 张鑫；

【导师】 束庆龙；

【作者基本信息】 安徽农业大学 ， 森林保护， 2007， 硕士

【摘要】 香樟黄化病（Choruses of camphor-tree）是近几年城市樟树发生比较普遍、危害比较严重的一种生理性病害。本论文通过对合肥市香樟的健康植株和不同黄化水平病株的营养状况进行测定,以明确香樟健叶和黄化叶营养状况的区别;探讨各元素对黄化病影响程度的大小,为提出合理的药剂配方提供理论指导;并在此基础上,通过对不同等级的樟树植株的主要生理特性进行测定分析,对比不同等级香樟的冠幅、新稍长度、叶片面积、叶片的解剖结构、叶片吸尘量、叶片重金属含量等的差异,揭示了樟树黄化病对樟树生态功能所产生的不利影响。同时本文按照樟树的需肥特点配置了3种药剂,采用注射滴灌法对黄化病进行了防治试验。初步找到了香樟黄化病的治病机理和防治方法,整个论文工作得到结果如下。通过对不同失绿黄化香樟根际和根丛土壤的营养分析,不同黄化程度根际土中N、P、K三种主要元素随失绿加重而增加。正常树根际中N、P、K含量比黄化株少,可能是由于黄化使香樟树势变弱,影响根系的生长,使根系的吸收能力下降。重度失绿树根际土中P明显出现富集,比正常树要高。一般认为高P使土壤中Fe²⁺发生沉淀包蔽于根表面,影响植物铁的吸收增加植物失绿程度。失绿黄化树根丛土中磷也明显高于土壤P的高值,可见,根际土壤的高P是诱导失绿黄化一个重要原因。调查研究香樟根部土壤的pH值和HCO₃^-浓度表明:土壤pH值过高、HCO₃^-浓度过大是引起黄化的最直接原因。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,多数黄化香樟生长地段的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。对香樟健康植株和不同黄化程度植株营养状况的分析表明:随着黄化程度的增加,樟树黄化植株叶片营养的Mg、B含量比健叶含量升高:N、Fe、zn、Mn含量呈明显降低趋势。P、K、Ca在健康植株和黄化植株之间的变化没有规律性;N、Fe、Zn的缺乏可能是某些条件下香樟植株黄化比较严重（叶片呈白色）的主要原因之一。香樟发生黄化病后,生长发育受到一系列的影响,其中最明显的是生长量下降,受病植株两年生枝条长度比正常生长的植株显著缩短,新叶的面积也明显变小。发生严重的植株嫩梢枯萎死亡,导致冠幅出现回缩现象。对不同失绿黄化程度叶片结构的观察表明,随黄化程度的加重,叶片厚度和叶肉厚度明显变小;栅栏组织的厚度随叶片黄化加重而变薄,叶绿素数量减少。海绵组织的厚度随黄化程度的加重有变薄的趋势,但差异不显著。单位长度上的细胞个数随黄化程度加重有减少趋势。香樟发生黄化病后,其生态功能也受到了很大的影响,本文通过对不同黄化等级的香樟叶片的吸尘量的测定发现,随着樟树黄化程度的增加,其叶片吸尘能力随之减小,通过对不同黄化等级的叶片硫元素含量的测定分析,黄化程度的增加,叶片中硫含量减少,叶片吸收硫的氧化物的能力减弱。通过对樟树叶片重金属含量的测定发现,黄化叶片中含有的重金属元素较健叶少,进而说明香樟黄化后对有害矿质元素的吸收能力也随之减弱。在对黄化香樟树干的注射滴灌矫治实验中,本文采用的三种含铁化合物都有一定的复绿效果,尤其是3号试剂（1.0%-1.5%硫酸亚铁加入0.5%-1.0%的尿素）,复绿效果最明显。通过对叶片的生理生化测定,叶片的酶活性、比叶重、单叶面积、叶绿素含量和净光合速率增幅最大,叶片解剖结构趋于正常,叶片中N、Fe、Zn的含量增加,Mg、B含量下降,元素间的比例趋于平衡,叶片表现正常,防治效果最好。更多还原

【Abstract】 Cinnamomum camphor yellow, a kind of physiological disease, became widespread and serious in urban condition. In this paper the analysis of nutrient element of the leaves from healthy and the leaves with different yellowing grade were carried; in the leaves and soil of around roots the main elements which affect yellowing were determined and compared; relationship between physiological characteristic, canopy of trees, the length of new shoots, the area and dissection structure of leaf and disease severities were investigated. The quantity of dust and the content of harmful metal elements attracted by leaf also studied. On the basis of these results, the three new regreening techniques that used by iron compounds were applyed in growth period to find the good methods for control the disease. The results were listed as fellows.The comparison of nutrient element around root system between healthy trees and sclerotic trees showed that choruses camphor-tree were high in nitrogen, phosphorus and potassium. It may be the disease decreases the growth of tree. The decreasing of the growth of camphor-tree roots may cause of the decreasing of absorb ability. The serious degrees of chlorotice tree were high phosphorus value of the root soil. This soil had high phosphorus that conducted the iron inactive and decreased the iron absorbing ability of the roots of camphor-tree .So the disease rank is increasing. The high phosphorous of the root zone soil is the main cause induced chlorosis.The results of investigation theHCO₃^- content and PH value of soil indicate: high soil PH valve and high HCO₃^- content of the soil is a immediate cause of the camphor tree 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 yellowing.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 efficiency of disease tree descends obviously. The carbon dioxide density of cell was increased with the disease index increased. There were negatively relation between the speed of the photo-synthesis of leaves and the carbon dioxide density of cell in leaves.As for the different structures of chlrotic leaf , with the increase of its chlorotic degree, the thickness of leaf and mesophy became small. The thickness of palsied tissue turned out to be thinner and its chlorophyl quantity was reduced for the increasingly serious degrees of chlortic leaves. The sponge tissue thickness had no obvious change. When the degrees of chlortic became more serious, the amount of cells decreased obviously in the unit of length.The camphor-tree suffering this disease of chlorotic, and its ecological functions are affected by a series of influences. The results of experiments in this article indicate: with the yellows index increased, the volume of dust-collection for a leaf is reduced; the content of Sulphur （S） element is lower; the capacity of absorbing in the S-oxidizebecomes weak. According as the content of harmful elements of the leaves of camphor-tree, the harmful elements of the leaves are less than that of healthy leaves, and it shows that the capacity of absorbing in the harmful elements of the tree turn out to be weak.In the correcting experiment on the branches of chlorotic camphor-tree, the experiment adopted the method of injecting fertilizer to three compounds, which regreen efficiently. No.3 [0.5%-1.0% CO（NH₂）₂ add to 1.0%-1.5%FeSO4] regent in particular, it regreens obviously. After the analyzing of the leaves, chlorotic tree rate and chlorosis index decreased apparently. The individual leaf area, leaf area/leaf dry weight ratio, the content of chloroplast pigment, net photosynthesis rate increased. The amatomical structure of chlorosis leaf was normal. N、Fe、Zn and active Fe contents in the leaves increased, and Mg、B decreased. These results balance of elements in leaf, and it presents normal condition. Therefore, it can reach to the best method of prevention and cure.更多还原