| Ginkgo biloba L.belonging to Ginkgoaceae, as relict plant of the oldest extant seed plants.In recent years, people often put ginkgo as courtyards, streets and landscaping of the preferred species.Beijing area as a street tree planting ginkgo tree, has not entered the normal metabolism of the leaves of the season, but have in June and July began appear different degree of leaf scorch becomes yellow phenomenon.Part of the urban streets and even 1/3 of the ginkgo tree appears such a situation, the streets of the landscape, green.But how this phenomenon is produced, the process of development, as well as the nature of the person has not given an accurate description.Not easily occurred and the rest of the ginkgo leaf scorch degree determines the phenomenon.Through investigation streets in different regions of Beijing gingko leaf scorch phenomenon occurred in the development process, clear the specific form of the disease and according to the ginkgo disease manifestations of the disease classification, control of different streets disease index and the incidence, ginkgo leaf scorch dry phenomenon of occurrence and street environment factor direct relationship.By collecting leaf samples, measuring the SPAD chlorophyll, catalase content and leaf nutrient element contents of and ginkgo leaf scorch phenomenon and the severity of leaf lost green degree, sturdy plants degree and whether the lack of relationship between the elements.The results are as follows:(1) Ginkgo leaf scorch phenomenon is formed by multiple environmental factors have effects on the plant physiological scorch phenomenon, and infectious diseases.This phenomenon usually occurs from the leaf margin, the leaves from the leaf edge of the beginning of the occurrence of green legs, dehydration and dry, to the back of the roll up.In the middle stage, withered leaf number increased, leaf scorch area from leaf margin to petiole direction.The final or the whole leaves are yellow, and petiole parts are dehydrated dry, dry and crisp, showing the withered state after the fall.(2) Leaf scorch phenomenon occurred in the whole plant of Ginkgo on at the same time,more uniform distribution.The survey found that ginkgo leaf scorch phenomenon and ginkgo trees planted Street direction, planting area of summer drought little rain climatic conditions, different streets and areas of curing processing factors.Street planting than Park planting onset of severe; fruiting female plants than male plant incidence of serious; the road is wide, traffic more street condition is more serious.Beijing region, in September to the end of 10 the most serious.(3) Because of the influence of high temperature.The lack of water in the ginkgo plant could not be supplied to the leaf margin of the leaf, leading to the dehydration and drying of the Ginkgo Biloba Leaves Extract Tablets from the leaf edge.In addition, Female Ginkgo biloba too much fruit will consume a plant’s own nutrition, should be early thinning.Have a certain relationship with the lack of ginkgo leaf scorch phenomenon of K elements.The results showed that the disease index and the street Ginkgo Biloba Leaves Extract Tablets K elements content, the two were negatively correlated.The disease index is higher in the street, Ginkgo Biloba Leaves Extract Tablets K element content is low.Street should pay attention to the application of K fertilizer.(4) In view of this phenomenon, this research proposed the suggestion of urban street greening maintenance.Should choose the strip or sheet for planting; planting soil should choose earthy and loose, good water permeability of soil, to protect plant roots and ensure adequate water supply; choice of male plants, plant diseases and insect pests of seedling transplanting; the focus on Jiaotou water to ensure plant roots can absorb enough water.Pay attention to irrigation time shall be selected to avoid the midday, sooner or later, watering; may be appropriate to fill the topdressing potassium and boron; trees nursery should not planting shrubs, timely weeding. |
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