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科学家们正在筛选能够在富硝酸盐培养基质中从空气中获得更多氮素营养的大豆突变型。据美国农业部科教局的植物生理学家James E·Harper及其伊利诺斯州大学的同事们估计,目前生长在美国中西部的大豆品种仅从空气中获得25—50％的氮素。大豆从土壤中吸收的追加氮素量同消耗氮素最多的玉米所需要的氮素总量一样多。大豆和其他豆科作物通过共生固氮作用从空气中获得氮素营养。某些细菌侵入植物根系引起根组织膨大隆起,即形成所谓的根瘤。在根瘤中,空气中游离的氮素转化为植物可以利用的氨态氮。
Scientists are screening for soy mutants that are able to get more nitrogen in the air from nitrate-rich culture media. According to plant biologist James E. Harper of the U.S. Department of Agriculture’s Bureau of Science and Education and colleagues at the University of Illinois, soybean varieties currently grown in the Midwestern United States harvest only 25-50% of nitrogen from the air. The amount of additional nitrogen absorbed by soybeans from the soil is as much as the total amount of nitrogen needed to consume the most nitrogenous corn. Soybean and other legumes derive nitrogen nutrition from the air through symbiotic nitrogen fixation. Some bacteria invade the roots of plants causing the root tissue to bulge, forming so-called nodules. In nodules, free nitrogen in the air is converted to ammonia nitrogen available to plants.