EFFECT OF CROP PRODUCTION FACTORS ON MAIZE YIELDS

The evaluation of the research was made using analysis of variance and regression analysis. The productivy and nutrient response of maize hy brids are significantly different. Hybrids which are able to produce h igh yields and greater revenue per hectare at smaller fertiliser doses are more valuable. Considering the aspects of efficiency and environm ent protection, maize needs only N60-120, P45-90, K53-106 kg/ha active agents. At N doses greater than N60-120 kg/ha quantity of NO3-N the 1 00-120 cm soil profile reaches 150-200 mg/kg, which could result in si gnificant environment pollution. The hybrids also have different plant density requirements. Plant number has a considerable effect on the y ield. Modem hybrids show flexible behaviour to increasing density and their optimum interval is wide. With on increase in plant number the i ndividual plant yield decreases but the yield per unit area improves. Of course plant number/ha can only be increased up to a certain limit, because above the optimum the yield decreases and sensitiveness to st alk fusarium grows. In the case of modem hybrids the connection beta e en the growing season and the plant number is not significant. Resista nce to increasing density is a genetically controlled characteristic o f hybrids. It is also influenced by ecological conditions, the year ef fect and the water supply. Crop rotations applied in the experiment: a ) triculture: pea - wheat - maize - maize; b) biculture: wheat - maize - maize - wheat; c) monoculture: since 1966. Maize tolerates a partia l monoculture seasonably well, but after 10-15 years of monocropping t he yield decreases by 1-3 t/ha in arid conditions compared to the yiel ds achieved in crop rotation. The best forecrop for maize was wheat. T he forecrop influences the fertilizer requirements. The best yields we re obtained as follows: in triculture (pea - wheat - maize) after whea t with a dose of 5060 kg/ha N, in biculture (wheat - maize) with a dos e of 60-80 kg/ha N, after maize in biculture with a dose of 80-100 kg/ ha N and in monoculture with a dose of 100-120 kg/ha N.