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在火炬松自然生长区的北部和更北的造林地区,当年树叶冬季变黄。在其余南部的火炬松林中,这种变黄一般与营养有关。这种现象常常被人们误认为是天冷引起的正常情况。为了解这一问题,冬季从树冠的顶部1/3处树枝上采取一些树叶,做试样,用塑料袋封存和其它试样一起放在干冰冷却器中,然后移到实验室冰箱中。每个试样与显示植物体素的曼塞尔颜色图中的标准颜色之一相比较。试样在强制通风的烘箱中干燥,在维利研磨机中研磨,然后分析总氮、磷、钾、钙和镁。用微量克氏方法测定总氮,其余的养分用蒲拉特方法
In the northern part of the natural growth area of Pinus taeda and in the more afforestation areas of the north, the leaves turn yellow in winter. In the remaining southern flamingo pine forests, this yellowing is generally associated with nutrition. This phenomenon is often mistaken for the normal condition caused by cold weather. In order to understand this problem, in winter, a few leaves were taken from the top 1/3 crown of the crown to make a sample, sealed in a plastic bag and placed in a dry ice cooler along with other samples and then moved to a laboratory refrigerator. Each sample is compared to one of the standard colors in the Mansell color chart that displays plant voxels. The samples were dried in a forced air oven, ground in a Willie mill and analyzed for total nitrogen, phosphorus, potassium, calcium and magnesium. Determination of total nitrogen with trace Kovar method, the remaining nutrients with the Bratrate method