The effects of ammonium nitrogen and nitrate nitrogen on alfalfa (Medicago sativa L.) early growth and nitrogen absorption
2000
Hirose, D. (Minamikyushu Univ., Takanabe, Miyazaki (Japan). Faculty of Horticulture)
A water culture system and 15N-labeled nitrogen was used to investigate why the growth of alfalfa treated with ammonium nitrogen exceeded the growth of alfalfa treated with nitrate nitrogen. Plants treated with ammonium nitrogen showed higher levels of dry weight, total nitrogen content, soluble nitrogen content, insoluble nitrogen content and 15N-labeled insoluble nitrogen content than plants treated with nitrate nitrogen. Just after 15N-labeled nitrogen treatment, the ratio of 15N-labeled soluble nitrogen content to 15N-labeled total nitrogen content in plants under conditions of nitrate nitrogen was higher than that in plants under conditions of ammonium nitrogen. The experimental results show that the growth of plants treated with ammonium nitrogen surpassed the growth of plants treated with nitrate nitrogen. This is because alfalfa absorbed more quickly the ammonium nitrogen than the nitrate nitrogen. Thus, it was shown that the protein synthesis ability of alfalfa is superior
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