EFFECT OF HERBICIDES AND THEIR APPLICATION DATES ON THE CONTENT OF PHOSPHORUS, POTASSIUM AND TOTAL NITROGEN IN POTATO TUBERS

The aim of the study was to determine the impact weed infestation control technologies on the mineral composition of potato tubers. The results of the research originated from a field experiment conducted in 2007-2009 at the Plant Breeding and Acclimatization Institute - National Research Institute in Jadwisin (52 degrees 29 ' N, 21 degrees 03 ' E). The experiment was designed with the method of random subblocks in a dependent system of split-plots, in three replications. Two factors were included: the first factor composed of potato cultivars, Irga and Fianna, and the second one comprising weed control methods: 1) control - without chemical protection, mechanical treatments; 2) extensive (every 2 weeks) from planting to row compaction; 3) Sencor 70 WG - 1 kg ha(-1) pre-emergence potato; 4) Sencor 70 WG - 1 kg ha(-1) + Titus 25 WG - 40 g ha(-1) + Trend 90 EC - 0.1% prior to the emergence of potato; 5) Sencor 70 WG - 0.5 kg ha(-1) after the emergence of potato; 6) Sencor 70 WG - 0.3 kg ha(-1) + Titus WG 25 - 30 g ha(-1) + Trend 90 EC - 0.1% after the emergence of potato; 7) Sencor 70 WG - 0.3 kg ha(-1) + Fusilade Forte 150 EC - 2 dm(3) ha(-1) after the emergence of potato; 8) Sencor 70 WG - 0.3 kg ha(-1) + Apyros 75 WG 26.5 g ha(-1) + Atpolan 80 SC - 1 dm(3) ha(-1) after the emergence of potato. After harvesting, the fresh weight of tubers assayed nitrogen, phosphorus and potassium according to the adopted methods. The use of herbicides to regulate weeds increased the content of nitrogen and phosphorus, and the amount of potassium was not dependent on the herbicides used and the timing of their application. Meteorological conditions had a significant effect on the content of nitrogen and potassium, the higher their accumulation was found in the dry year, the lowest in the year with a higher amount of rainfall and lower amplitude of air temperatures.