The effects of different water supply cropyears (2007 year=dry, with water stress; 2008 year=optimum water supply) on the yields and agronomic traits of wheat in different crop models (crop rotation, fertilization, irrigation) were studied. In non-irrigated treatment the maximum yields of winter wheat were 5590 kg ha -1 in biculture (maize-wheat) and 7279 kg ha -1 in triculture (peas-wheat-maize) in 2007 year characterized by water-deficit stress. In 2008 (optimum rain amount and distribution) the maximum yields were 7065 kg ha -1 (biculture) and 8112 kg ha -1 (triculture) in non irrigated conditions. In water-deficit stress cropyear (2007 year) the yield-surpluses of wheat were 2245 kg ha -1 (biculture) and 1213 kg ha -1 (triculture), respectively. The nutrient utilization of wheat was modified by abiotic (water) and biotic (leaf- and stem-diseases) stress. The fertilization surpluses of wheat were 2853-3698 kg ha -1 (non-irrigated) and 3164-5505 kg ha -1 (irrigated) in a dry cropyear (2007) and 884-4050 kg ha -1 (non-irrigated) and 524-3990 kg ha -1 (irrigated) in an optimum cropyear (2008). The optimum fertilizer doses varied N 150-200+PK in biculture and N 50-150+PK in triculture depending on cropyear and irrigation. The abiotic stress (water deficit) influenced the agronomic traits (diseases, lodging) of winter wheat. The optimalization of agrotechnical elements provides 7,8-8,5 t ha -1 yields in dry cropyear and 7,1-8,1 t ha -1 yields of wheat in good cropyear, respectively.
