论文部分内容阅读
本文综述了世界一些地区柑桔氮肥施用试验的结果。得到的结论是每株成年柑桔树含氮1—2公斤,其中有30—60%在一年生部位(叶片和果实)中。每年有30克氮贮存于树体中。每公顷年施氮200公斤足以维持较高的柑桔产量和树体发育。氮肥中约有一半进入果实,十分之一贮存于树体。柑桔结果时吸氮量最高,冬季吸收最低。春季桔树吸收土壤氮还很少时,老组织中贮存的氮对展叶和花的发育起重要作用。土壤有机质中的氮和树体中的氮对正在发育中的器官的氮素供应起重要作用,氮素化肥用量低时更是如此。
This paper reviews the results of citrus nitrogen application trials in some parts of the world. The conclusion is that each adult citrus tree contains 1-2 kg of nitrogen, 30-60% of which are in annuals (leaves and fruits). Thirty grams of nitrogen is stored in the tree every year. 200 kg of nitrogen per hectare is enough to sustain higher citrus yield and tree development. Approximately half of the nitrogen enters the fruit and one tenth is stored in the tree. The highest nitrogen uptake results in citrus, the lowest absorption in winter. Nitrogen absorbed by the soil in spring is still low, nitrogen stored in the old tissue plays an important role in the development of leaf and flower. Nitrogen in soil organic matter and nitrogen in the tree play an important role in nitrogen supply to developing organs, especially at low N fertilizer levels.