Relationship between spectral vegetation indices and crop parameters of maize under nitrogen and water stress

Abstract

Field experiments were conducted at the Tamil Nadu Agricultural University, Coimbatore, Tamilnadu, India during kharif and rabi season of 2014 with maize crop (TNAU maize hybrid Co 6). To ensure the stressed environment, the crop was subjected to two irrigation levels (IW/CPE: 0.80 and 0.50) and five staggered nitrogen levels (0, 50, 75, 100 and 125 per cent of recommended dose of nitrogen (RDN). The experiment was laid out in randomized blocks design RBD (Factorial) with three replications. A higher value of spectral vegetation indices viz., NDVI, GNDVI, RVI, LCI, IR-RED and SR were recorded with irrigation at IW/CPE ratio 0.80 either with 100 or 125 per cent RDN (unstressed) applied to maize crop. Maize under stressed environment recorded reduced values of spectral vegetation indices when the crop was irrigated at 0.50 IW/CPE ratio with no nitrogen. All the spectral vegetation indices expressedpositive correlation (highly significant at 1 per cent probability level) with crop parameters. The overall best fit was linear with a regression coefficient between vegetation indices (GNDVI, NDVI) and with crop parameters, and actual grain yield and predicted yield (0.81 to 0.85) of maize. The ability of spectral vegetation indices to quantify the combined effect of nitrogen and water stress on maize too early through remote sensing paves the way for large scale application of satellite remote sensing.