The early prognosis of tuber yield based on nitrogen status in potato tops

Abstract

The pattern of nitrogen net change (ΔN) in potato tops during the period extending from BBCH 33 to BBCH 40 crucial for tuber yield (TY). This hypothesis was verified based on data from field experiments (2006–2008) wsequentially added nutrients (0, NP, NPK, NPKS, NPKSMg) to potato. The water shortage in June/July 2006 and June 2008 significantly affected N content, and in turn TY. The TY was reduced by 38% in 2006 and by 23% in 20as compared to 2007 (53.7 t/ha). The N content in potato tops at BBCH 40 of 2.5% indicated the lowest TY, where4.3% the maximum TY. The ΔN of +0.4% within the period from BBCH 33 to BBCH 40 determined the optimrange of the N content for the maximum TY (3.9–4.3%). The ΔN trend depended on the change of phosphorus apotassium contents. The key reason of N inefficiency was the shortage of potassium (K), resulting in its negligichange within this period. The pattern of zinc content at BBCH 40 reflected fairly well disturbances in N as well K supply to potato. A good supply of K and Zn to potato can improve N management just before tuber initiation.