Potato (Solanum tuberosum L.) productivity is strongly influenced by nitrogen (N), which regulates plant growth, biomass formation and tuber development. This study aimed to evaluate nitrogen accumulation and its relationship with biomass and yield, and to verify nitrogen use efficiency (NUE) assessment by comparing field trials with pot and in vitro experiments. Field experiments were conducted in Priekuļi, Latvia, under organic (OF) and integrated (IF) farming systems and in vitro experiments under controlled conditions. Pot trials were carried out in Jelgava. Three varieties (‘Monta’, ‘Prelma’, ‘Jogla’) were tested. Nitrogen was applied at 60 kg N ha⁻¹ in IF field plots; pots received 60 and 120 kg N ha⁻¹, while in vitro treatments included 7.5, 20 and 60 mmol L⁻¹ N. Nitrogen content in tubers was significantly affected by growing year and variety in both field systems (p < 0.05), with a significant year × variety interaction in OF. ‘Prelma’ consistently showed the highest nitrogen content, whereas ‘Jogla’ had the lowest across systems. Yield varied substantially among years and cultivation systems. In IF, ‘Jogla’ produced the highest yield, while in OF ‘Prelma’ performed best; ‘Monta’ had the lowest yields in both systems. In pot experiments, the highest yield was obtained at 120 kg N ha⁻¹, particularly for ‘Jogla’. Nitrogen use efficiency (NUE) decreased with increasing N rate. The relationship observed under field conditions that earlier-maturing varieties have lower NUE than later-maturing ones could not be confirmed in the in vitro and pot experiments. Overall, consistent varietal responses across systems indicate that controlled-environment methods can support NUE evaluation in potato research.
Taškova et al. (Thu,) studied this question.