Studies On The Mechanism, Ill Influence And Correcting Technique Of Camphor Tree Yellow

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.