DIGITAL IMAGE PROCESSING IN THE EVALUATION OF NITROGEN NUTRITIONAL STATUS IN MAIZE CROP

Resumen

The use of information derived from conventional digital images can represent a low cost and widely accessible alternative for estimating nitrogen nutrition in various agricultural crops. This study aimed to evaluate the feasibility of using smartphone based digital images in the visible (RGB) spectrum to assess nitrogen status in maize. The experiment was carried out using a randomized block design, with three replicates, in a 2 × 5 factorial scheme, consisting of the absence and presence of biostimulant and five nitrogen doses (0, 50, 100, 200 and 400 kg·ha^-1 of N) applied as topdressing. Relative chlorophyll index measurements were performed using a chlorophyll meter and digital images were obtained using a smartphone at the V8, V10 and R1 phenological stages. At the V10 and R1 phenological stages, leaf samples were collected to determine leaf nitrogen content using the semi-micro Kjeldahl method. Application of the biostimulant did not influence the SPAD index orle af nitrogen content of the different maize hybrids. There was a positive linear correlation between the SPAD index and leaf nitrogen content in maize at theV10 and R1 phenological stages, with values of 52.42 and 55.15, respectively. Twelve of the 17 spectral parameters evaluated were effective in assessing the nutritional status of maize plants at the V8, V10 and R1 stages, particularly the R band. Smartphone based image analysisis a valuable tool that enables rapid, non invasive, and non destructive estimation of nitrogen in maize crops directly in the field at low cost, there by promoting smarter and more sustainable agriculture. Accordingly, the development of a mobile application based on the obtained findings could significantly increase accessibility and usability for stakeholders.