The use of hand-held chlorophyll meters as a tool to assess the nitrogen status and to guide nitrogen fertilization of potato crop

Fifteen experiments were carries out in different sites of Italy, Belgium, Scotland and The Netherlands from 1995 to 1999 to study the possible use of chlorophyll meter to assess the nitrogen status and to ghuide nitrogen fertilization of the potato crop. The results are gathered here and reviewed together with the available information in literature. The paper deals with measuring principles of chlorophyll meter; relation between chlorophyll meter readings and analytical measurements of chlorophyll , analytical measurements of nitrogen content, tuber yield, and physiological processes in leaves; variations in chlorophyll meter readings related to nitrogen supply, potato cultivar, crop management, and sampling methods; use of chlorophyll meter readings for decision making in the management of supplemental nitrogen fertilization (assessment of chlorophyll meter critical threshold, plant response to addition of supplementary N)