The SPAD Chlorophyll Meter (SPAD) measures the chlorophyll content of leaves, and
can be used to estimate the nitrogen status of plants as an alternative to the nitrate tissue test. The leaf nitrogen monitoring in experimental plots consists of sampling, drying, weighing, grinding and finally the N measurement of the leaves. Data obtained in some crops like wheat, maize, barley and peanut from the SPAD chlorophyll meter showed reasonable estimation of leaf nitrogen characters (LNCs): %leaf N, specific leaf weight (SLW) and specific leaf nitrogen (SLN). Leaf color and the resulting SPAD reading
however, may vary by cultivar, soil and air temperature; planting date, leaf stage, leaf
position, plant disease, nutrient deficiency and plant stress. In this study, we hypothesized that the SPAD reading in lentil leaves could estimate leaf nitrogen content.