Nitrogen for plant nutrition is mainly obtained from three sources: nitrogen-fixing plant, rain water and manure.

氮素是植物必要的营养元素之一，其主要来源有：生物固氮作用、降雨和灌溉水以及人工施肥。

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Method: Selecting the optimum carbon sources, nitrogen sources and inorganic salt to get the optimum liquid medium recipe by the orthogonal test in three factors and four levers;

方法：采用深层培养方法，筛选出较优的碳源、氮源、无机盐，设计三因素四水平的正交试验，筛选大杯伞的最适培养基；

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