In Szeged-Öthalom, we carried out experiments in four growing seasons (2003/2004, 2004/2005, 2005/2006, 2006/2007) with four wheat species (GK Garaboly, GK Kalász, GK Petur, GK Holló) and two seed densities (300 seed/m2, 500 seed/m2) on salty meadow chernozem soil, where two different sowing date treatments (mid-October and early November) was evaluated. We took samples before harvest in the fields during the full ripening period of the plants. The curve of plant development has been evaluated with the cumulative yield production analysis of Sváb.

The yield production of a certain area has several yield components, which determine the volume of the yield altogether. Certain ecological and production-technological factors, such as sowing density, sowing date, and year have significant influence on the development of winter wheat, as well as on the final products of certain development stages and yield components. This is why the examination of yield production elements is more efficient for the detection of the effects of certain production factors and their possible changes, in comparison with the analysis of yield production only.

Our results show that the reduction of sowing seed quantity has lower risk at mid-October seeding time, than at early November sowing. The varieties have well-separable development characteristics, but the investigated yield components of the genotypes are significantly modified by the cultivation and environmental circumstances (number of seeds, sowing date, nutrient application, crop year, production site).

Keywords: winter wheat, genotype, seeding rate, sawing date, yield components, relative development