Summary

The importance of a quality-performed seeding in the wheat production technology is associated with the seed quality, time and method of seeding, seed depth and density. Optimums have been determined for almost all the factors mentioned, but certain dilemmas regarding wheat seed density have always existed. Owing to the wheat specificity, microclimate in different wheat growing regions and its interaction with other elements of cultural operations, seed density has been a continually investigated subject matter. The aim of these investigations was to determine the simultaneous effect of seed density and nitrogen nutrition level on the plant height and spike length, being an important indicator of potential yield, by growing two morphologically divergent cultivars in the production conditions of the Cacak valley. The nitrogen rates selected (60 and 90 kg/ha) are practically the most commonly used ones in the region mentioned. For the purpose of some theoretical explanation, apart from the seed densities most usually applied (ranging from 450 to 750 grains/m2), the investigations included those varying from 300 to 900 germinating grains/m2. Though plant height is a wheat varietal trait, rather ununiform results by study years were obtained. The highest plants were those in the densest crop stand, particularly when compared to the ones in a sparse stand. Nitrogen caused a considerable wheat height increase, and the cultivar Yugoslavia was always very significantly higher than the Rana Niska variety. As opposed to the plant height, the greatest average spike length was obtained in the lowest seed density, and most differences between the densities were statistically highly significant, especially in the cultivar Yugoslavia. Nitrogen positively affected this property as well, and very significant differences between the investigated cultivars were established. The three-year-study results indicate that winter wheat seed density, at a optimal time of seeding, should range between 450 and 600 germinating grains per m2 which, coupled with the confirmed importance of nitrogen nutrition in the formation of longer spikes with a greater number of spikelets and grains and of greater grain weight, contribute to a pronounced increase in the bread wheat yield, which is what all wheat producers actually want and aim at.

           Key words: wheat, seed density, nitrogen, plant height, spike length.