Assessment of Nitrogen Nutrition Index of Winter Wheat Canopy from Visible Images for a Dynamic Monitoring of N Requirements

Hand-held chlorophyll meters or leaf-clip-type sensors indirectly and instantaneously measure leaf N content. They can provide an nutrition index (NNI) value that is crucial information for adjusting the amount of fertilizer to actual status plant. Although these measurements are non-invasive non-destructive, they require numerous repetitions at canopy scale. The objective this work was explore potential visible images predict nitrogen in winter wheat crops from estimating NNI compare results with those deduced classical methods. Based on a dark green colour (DGCI), which combines hue, saturation brightness, normalized DGCI (nDGCI) proposed as ratio between study microplot over-fertilized microplot. methodology performed microplots gradient. Half were grown single cultivar (LG Absalon) other half mixture four cultivars. impact optical device (digital camera smartphone), white balance (Manual Automatic), crop growth stage (two-nodes heading) cultivars (single mixed) relationship (DGCI, nDGCI) evaluated. showed close correlation nDGCI values NNI_NTester values, especially Absalon; R2 = 0.73 up 0.91 smartphone). It suggested highly sensitive cultivar. This approach no specific calibration promising estimation requirements field.