问:什么叫常量元素和微量元素?它們是怎样区分的? 答:植物在生长发育过程中需要吸收各种营养元素,以构成植物体的各种物质。根据分析结果,在植物体內所发現的元素約有六、七十种之多,但它們在含量上,相差极为悬殊,从百分之几十直到十万分之几以下。一般把含量占植物体干重千分之几以上元素叫常量元素,含量在万分之几到十万分之几的叫做微量元素。植物体內含有的几十种元素,是否都是植物生活不可缺少的呢?在这方面科学家进行了很多研究工作。研究的方法是利用水培法或砂培法,有意地不供給植物某种元素,看它能否正常生长发育。早在十九世紀五十到六十年 Q: What are the constant elements and trace elements? How are they distinguished? A: Plants need to absorb various nutrients in the process of growth and development to form various substances in the plant body. According to the results of analysis, there are about sixty to seventy kinds of elements found in plants, but their content is quite different from tens of thousands to below one hundred thousandths. In general, the content of dry plant weight accounted for a few thousandths of the above elements are called constant elements, the content of a few thousandths to ten thousandths is called trace elements. Dozens of elements contained in plants are indispensable to plant life? In this regard, scientists conducted a lot of research work. The research method is to use the hydroponics or sand culture method, intentionally not to supply some element of the plant and see if it can grow and develop normally. As early as the nineteenth century fifty to sixty years