Wpływ systemów uprawy roli, gęstości i terminu siewu na zmienność plonowania odmian pszenicy ozimej

The investigation aimed at analyzing the variability in winter wheat cultivars yielding as depending on the tillage system, density and term of sowing. There were used two systems of tillage: conventional (plughing) and simplified. In each of them regarded were the following factors: I – terms of sowing: a) 14–16 September (early sowing); b) 1–3 October (optimum sowing); 15–17 October (delayed sowing); two sowing densities: A – 3000 grains per a square neter; B-450 grains per a square meter; III – winter wheat cultivars: Finezja, Rywalka, Kobiera, Satyna, Bogatka, Zawisza. At conventional tillage the optimum sowing term appeared conducive to stable yields of winter wheat, while delayted sowing term at simplified tillage and early at plough tillage were bringing about a considerable differentiation in the yields of the cultivars tested. The cultivar Finezja sown at the early term in decreased density show a tendency to produce higher yields as compared to those obtained at the optimum term, irrespective of the system of tillage. On the other hand, higher yields of the Satyna cultivar were obtained in conditions of early sowing term and simplified tillage. Cluster analysis revealed that the yields of Finezja anad Rywalka cultivars were depending on the sowing density to a lesser degree than those of the other cultivars tested.