Chemical composition, nitrate reductase activity and plastid pigments content in lucerne under the influence of ammonium and nitrate form mineral nitrogen

V. Vasileva and A. Ilieva

Institute of Forage Crops, 89 Gen. “Vladimir Vazov” Str., Pleven 5800, Bulgaria, E-mail: viliana.vasileva@gmail.com

Abstract:

A pot trial was carried out at the Institute of Forage Crops, town of Pleven, Bulgaria (2003–04). Whereas ammonium and nitrate forms of mineral nitrogen are assimilated for the plants, the influence of these two forms of mineral nitrogen on the chemical composition, nitrate reductase activity and plastid pigments content of lucerne in conditions of optimum moisture and water deficiency stress was tested. Urea as a source of ammonium nitrogen and potassium nitrate as a source of nitrate nitrogen were used. Rates of 70, 140 and 210 mg N kg-1soil were applied. It was found that mineral nitrogen in ammonium form, applied at the doses of 140 and 210 mg N kg-1 soil at optimum moisture increased crude protein content by 5–13%, and in the nitrate form at the same doses, by 3–7%. Crude protein content under water deficiency stress increased by 4–21% for ammonium, and by 3–12% for the nitrate form of mineral nitrogen. When the plants were supplied insufficiently with nitrogen, water deficiency stress more strongly deteriorated the chemical composition of lucerne, crude protein decreased by 6% and crude fiber increased by 10%. The application of mineral nitrogen under optimum moisture decreased calcium and phosphorus content, and the decrease was bigger for the nitrate form (up to 10% for calcium, and 23% for phosphorus). Under water deficiency stress the content of calcium and phosphorus decreased, but there were no differences for two forms of mineral nitrogen. At the optimum moisture and water deficiency stress, there was a similar tendency to reduce nitrate reductase activity in leaves, when applied mineral nitrogen at a dose of 70 mg N kg-1 soil in both forms, and to increase at the doses of 140 and 210 mg N kg-1 soil. The total content of plastid pigments increased as compared to unfertilized control, when mineral nitrogen was applied in both forms.

Key words:

ammonium nitrogen, crude protein, lucerne, nitrate nitrogen, nitrate reductase activity, plastid pigments

Effect of presowing treatment of seeds with insecticides on nodulating ability, nitrate reductase activity and plastid pigments content of lucerne (Medicago sativa L.)

V. Vasileva and A. Ilieva

Institute of Forage Crops, Gen. Vl. Vazov Str. 89, Pleven 5800, Bulgaria;e-mail: viliana.vasileva@gmail.com

Abstract:

To determine the effect of presowing treatment of seeds on the nodulation ability, nitrate reductase activity and plastid pigments content of lucerne (cv. Obnova), a pot trial was carried out at the Institute of Forage Crops – Pleven, Bulgaria. The insecticides Promet 400 SK (furathiocarb) at the dose of 3 L, and Carbodan 35 ST (carbofuran) at the dose of 1, 2 and 3 L 100 kg-1 seeds were used. It was found that the insecticides tested did not depress the nodulation. Nodule number and specific nodulation ability when treated with Carbodan 35 ST at the dose of 3 L 100 kg-1 seeds exceeded that of the control by 23% and 7%, respectively. The root length for the variants with presowing treatment of seeds was higher as compared to the control by 7 to 26%. The variant with Carbodan at the doses of 2 and 3 L 100 kg-1 seeds and Promet increased nitrate reductase activity in roots, and that with Carbodan at the dose of 1 L 100 kg-1 seeds- in the leaves. Total content of plastid pigments increased in all variants with Carbodan and was lower than the untreated control in the variant with Promet.

Key words: