NITROGEN ACCUMULATION AND FORAGE PRODUCTION IN LUCERNE (MEDICAGO SATIVA L.) UNDER MINERAL NITROGEN FERTILIZATION AND WATER DEFICIENCY STRESS

Abstract

 A pot trial was conducted at the Institute of Forage Crops, Pleven, Bulgaria during 2003-2004 to study the effect of mineral nitrogen fertilization and water deficiency stress on nitrogen accumulation and aboveground and root mass of lucerne as source of forage. Mineral nitrogen fertilizer (ammonium nitrate) was applied at the doses of 40, 80, 120 and 160 mg N kg-1 soil. Water deficiency stress was imposed for 10 days at the budding stage of lucerne by stopping the irrigation till soil moisture dropped to 37-40% field capacity. It was found that mineral nitrogen fertilization increased nitrogen in aboveground dry mass for doses of 120 and 160 mg N kg-1 soil in the conditions of optimal moisture by 21 and 37%; and for doses of 80 and 120 mg N kg-1 soil and water deficiency stress, by 14 and 12%, respectively. Mineral nitrogen fertilization had a stronger effect on nitrogen in dry root mass yield compared to the aboveground dry mass. The negative effect of water deficiency stress on nitrogen in aboveground and root dry mass was lowest when applied 80 mg N kg-1 soil. The findings of this study can be utilized in lucerne cultivation under drought stress for obtaining good forage production with little nitrogen fertilization. This will save the environmental pollution as well as the cost of forage production.