Evaluation of SPAD meter values for estimating rice nitrogen status

Abstract

A field experiment with six rice genotypes were conducted to relate SPAD chlorophyll meter readings to variables reflecting nitrogen (N) status at different developmental stages. These indices can be used to predict foliar N concentration in rice without significant interferences of rice genotypes and growth stages. Dependence of nitrogen content from mineral element in the soil was established at the same time. Investigations were guided on six fertilization variants (N1: 0; N2: 40; N3: 60; N4: 80; N5: 100; N6:150 kg N ha-1). The results indicated that nitrogen content influenced from presence and ratio mineral elements in the soil. SPAD value increased with increase in N level and growth stages upto FL stage. However no clear trend is observed among cultivars, since ratio of SPAD readings to predict rice N status is not influenced by rice genotypes and is based on the principle of N translocation from old to young leaves when the plant is nitrogen deficient.