The assumption of this study was that the nitrogen (N) concentration in potato organs during the growing season is a useful tool for making prognosis of the tuber yield. This concept was validated based on data from field experiments (2006-2008) with sequentially added nutrients (0, NP, NPK, NPKS, NPKSMg) to potato. The N concentration was measured in potato vines, stolon, and the small-sized potato tubers during the crop growing season in 10-day sequences starting from BBCH 33. The seasonal pattern of N concentrations in potato organs, including tubers, was significantly dependent on the weather and modified by the applied nutrients. The nitrogen concentration in stolon + roots and in the small-sized potato tuber was much smaller compared to vines. The nitrogen concentration in vines followed a declining trend, which was described the best by the power function. It showed the predictive usefulness, based on pooled data, on 68 day after planting (DAP). The pattern of N concentrations in stolons + roots was significantly distinct for the unfertilized and fertilized plants. Its predictive value for pooled data was the strongest on 78 DAP. The N trend in the small-sized potato tuber, irrespective of the treatment, followed a 3rd degree function. The yield prediction based on sets of yearly data, irrespective of the weather course, clearly showed that the best sampling date, regardless of the potato part, occurred in the early bulking stage (89 DAP).  

24.4.2019