In a field experiment, the yield and protein content of winter wheat were examined in two crop rotation systems (bi- and tri-culture), two water supply systems (non-irrigated/irrigated), five nutrient supply levels, and three genotypes. The aim of this experiment was to examine the individual factors and evaluate the various interactions. The results of the experiment showed that there was no significant difference between water supply and genotypes in terms of either yield or protein content. Under the influence of water supply, an average yield increase of 595 kg/ha can be achieved in the case of biculture, while in the case of triculture, an average yield increase of 512 kg/ha can be achieved. In terms of protein content, a decrease can be observed under the influence of irrigation: 0.2% in the case of biculture and 0.28% in the case of triculture. In all four studied treatment combinations, the Hycardi hybrid wheat achieved the highest yield (non-irrigated biculture: 8173 kg/ha; irrigated biculture: 9088 kg/ha; non-irrigated triculture: 10 256 kg/ha; irrigated triculture: 10 763 kg/ha), but this did not differ significantly from the yield results of the other two genotypes. In contrast, significant differences were found between the crop rotation systems. In the triculture crop rotation system, the yield (2044 kg/ha under non-irrigated conditions and 1961 kg/ha under irrigated conditions) and protein content (2% under non-irrigated conditions and and 1.02% under irrigated conditions) than in the two-crop rotation system. There were significant differences between nutrient supply levels. Increasing fertiliser doses also increased yield and, typically, protein content.