EFFECT OF LOW RATES OF MINERAL FERTILIZERS ON THE PRODUCTIVITY OF DURUM WHEAT (Triticum durum Desf.)

The aim of the study was to determine the effect of nitrogen and phosphorus fertilization applied at low rates on grain yield and some physical and chemical parameters for the durum wheat variety Progress. Nitrogen and phosphorus fertilizers were applied given in doses of 0, 40 and 80 kg/ha alone and in various combinations. A stationary trial with fertilization has been carried out since 1966 in the experimental field of Field Crops Institute in town of Chirpan, Bulgaria. The study included 2016 and 2017 crop years. It was found that the fertilizer rate increase did not necessarily lead to an increase in the studied parameters. The highest values were reported as follows: grain yield at N80P80; thousand-kernel weight at N-40; test weight at N40P40; vitreous of grain at N-80; protein content at N-80 and gluten at N80P40. Correlation analysis showed the strongest and most significant correlations between protein content and gluten (0.906**).