Zmienność plonowania ziemniaka w zależności od jego koncentracji w płodozmianie, doboru odmian i przedplonów

The investigation covers a three-year (1993-1995) period of many years field experiments with six-coarse crop rotations with different proportions of potatoes: fodder cereal crop rotation 16,7%; potato-cereal crop rotation 33,3%; and potato crop rotation 50,0% G. rostochiensis, Ro 1 non-resistant cvs. Bronka and Lena and resistant cvs. Fala and Ibis were used. Potatoes followed both non-cereal and cereal forecrops. A static experiment has been continued since 1987 on a grey-brown podsolic soil, developed from sandy loam on fine sandy soil, rich in available nutrients. A negative reaction of potatoes to their percentage increase in crop rotation was found, higher in non-resistant than in resistant cultivars to G. rostochiensis. In the fodder-cereal rotation, after lucerne with red clover, all cultivars produced yields which approximated each other, averaging 38,6 t/ha. A drop in yields in non-resistant cultivars was 13,3% in the potato-cereal rotation and 20,2% in the potato rotation, and in resistant cultivars it was 1,1% and in non-resistentl2,0%, respectively. There was also a relationship between yield quality, population of G. rostochiensis and cultivars.