Monitoring Wheat {Triticum aestivum L.) Leaf Nitrogen using Diagnostic Tools for Fertilizer Nitrogen Management

摘要

A field experiment was conducted to evaluate the leaf colour chart (LCC) and chlorophyll meter (SPAD and fieldscout chlorophyll meter (FSCM)) for developing site specific nitrogen (N) management strategy in wheat (Triticum aestivum L.). Four levels offertilizer N (0, 70, 140 and 210 kg ha1) were used to determine the growth stage specific optimum LCC, SPAD and FSCM chlorophyll meter values for achieving economic optimum grain yield. A positive and significant (R2 = 0.93-0.97, p<0.01) quadratic response between N application levels and wheat grain yield was observed. Economic optimum grain yield of 4.68 t ha-1 (first year) and 4.57 t ha"1 (second year) corresponding to economic optimum dose of 141 and 144 kg N ha1, respectively were observed using quadratic response function. Nitrogen concentration in fully expanded youngest leaf correlated significantly (p<0.01) and positively with LCC score (r = 0.89), SPAD value (r = 0.94), FSCM value (r = 0.68) and total chlorophyll concentration (r = 0.91). Two chlorophyll meters used in the study were calibrated with a significant (p<0.01) linear response as 'FSCM value = 11.3>