Evaluation of Chlorophyll Meter Data for Nitrogen Fertilizer Management in Maize (Zea mays L.)

摘要

In order to achieve high yield of maize (Zea mays L.) farmers in many parts of Iran tend to apply nitrogen fertilizer (N) in excess of the crop requirements. Excessive N input in the beginning of growth season is the major cause of the poor fertilizerefficiency. Only less than 20% of the total N uptake by maize occurs before V8. Environmental and economic considerations require that nitrogen fertilizer should be applied only in quantity and time which is strictly justified. Improving N management would eventually depend on the accuracy with which the N status of plant can be assessed. The usefulness of SPAD chlorophyll meter readings for plant N assessment is based on the direct proportionality between the leaf chlorophyll and the leaf N concentration. By using the critical value of SPAD it is possible to determine the best time for N application.