The contribution of yield components in determining the productivity of winter wheat (Triticum aestivum L.)

The aim of the present study was to determine the effect of different growth regulator rates and nitrogen fertilization levels on yield components and to evaluate their influence on winter wheat productivity. A field experiment with winter wheat ‘Muza’ was conducted at the Czeslawice Experimental Farm, belonging to the University of Life Sciences in Lublin, Poland over the period 2004–2007. In this experiment, the effect of the studied factors on yield and its components was primarily dependent on weather conditions during the study period. An increase in nitrogen rate from 100 to 150 kg ha −1 in 2005 and 2007 had a significant effect on the increase in grain yield per unit area. In 2005, the grain yield rose through increased spike density (by 6.3%) and a higher number of grains per spike (by 1.6%). The 1000-grain weight decreased the grain yield per unit area (by 0.04 t ha −1 ). In 2007, the higher yield of wheat fertilized with nitrogen at a rate of 150 kg N ha −1 was positively affected by all the three yield components. The statistical analysis of the results showed that the winter wheat grain yields were also significantly affected by the retardant rates applied depending on the year.