G. Panayotova1*, M. Almaliev2, S. Kostadinova2
1Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Department of Agrochemistry and Soil, Faculty of Agronomy, Agricultural University, 4000 Plovdiv, Bulgaria
(Manuscript received 29 September 2016; accepted for publication 30 January 2017)
Abstract. Nitrogen uptake and expense of durum wheat were studied under the conditions of fertilized field experiment on soil type Pellic vertisol. The seven genotypes – Progress, Vazhod, Victoria, Predel, Deana, Zvezdica and Elbrus selected at the Institute of Field Crops – Chirpan, Bulgaria, were grown in two field crops rotation of cotton and durum wheat under rainfed conditions for a period of three vegetations in years 2011-2013. The spring treatments of nitrogen as NH4NO3 were as follows: N0, N60, N120 and N180. The total N uptake in the above ground biomass of durum wheat increased with the amount of applied nitrogen and during climatically favorable years reached 220 kg N.ha-1. A tendency was found that the new genotypes uptook more N, compared to varieties Progress and Vazhod. The N expense of the new cultivars Predel and Zvezdica showed the highest amount of N per 1 ton of grain, 40.7 and 41.1 kg, respectively. Strong positive correlation was found between N fertilization and N uptake and expense for 1 ton of grain. The regression model indicated that N uptake with the grain and straw and N expense depending on N fertilization occurred with delay. With N fertilization of durum wheat at rates of up to 180 kg N.ha-1 each kilogram of applied N fertilizer increased the average expected N uptake with 7 kg.ha-1 and N expense with 0.66 kg.ton-1 grain.