In the report, the influence of applied plant growth regulators and weather conditions on the colour of perennial ryegrass cultivars was shown. The results were obtained on the basis of field experiments in which four cultivars of perennial ryegrass were used: Inka, Lisuna, Sabor, Figaro. Grasses were exposed to three plant growth regulators: Moddus 250 EC, Bercema CCC, Flordimex 420 SL. The experiment was conducted in the experimental plot of the University of Natural Sciences and Humanities in Siedlce (52°10’ N; 22°17’ E) in 2003-2005. Tested cultivars of perennial ryegrass were characterized by a uniform colour, but statistically significant differences occurred between individual years of research. In the case of growth regulators, a trend related to reduction in the overall assessment of lawn colour was shown in the tested cultivars. The results obtained show that among growth regulators, Moddus had the strongest effect on the colour of the tested cultivars. It was proved that retardants applied differently affected the colour of lawns in individual months and years of the study.

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