Nitrogen content in yield of dry aboveground and root mass of forage lucerne (Medicago sativa L.) after mineral nitrogen fertilization and water deficiency stress

摘要

The effect of mineral nitrogen fertilization and water deficiency stress on nitrogen content in yield in dry aboveground and root mass of forage lucerne was tested at the Institute of Forage Crops, Pleven, Bulgaria (2003-04). Mineral nitrogen fertilization at the doses of 40, 80, 120 and 160 mg N kg-1 soil was tested in pot trials. Nitrogen fertilizer was applied as ammonium nitrate. Ten-day water deficiency stress at the budding stage of lucerne was imposed by stopping the irrigation till soil moisture dropped to 37–40% FC. It was found that mineral nitrogen fertilization increased nitrogen in dry aboveground mass yield – for doses of 120 and 160 mg N kg-1 soil in the conditions of optimal moisture, by 21 and 37%; for doses of 120 and 80 mg N kg-1soil and water deficiency stress, by 12 and 14%. Mineral nitrogen fertilization had a stronger effect on nitrogen in dry root mass yield compared with that in dry aboveground mass. The negative effect of water deficiency stress on nitrogen in dry aboveground and root mass was lowest when 80 mg N kg-1was applied to the soil.