Utilização de aeronaves remotamente pilotadas para o monitoramento especial da cultura do milho em função das doses de nitrogênio

Abstract

The geotechnologies of precision agriculture (PA) assist professionals in evaluating agronomic characteristics of plants, optimizing time and decision-making. Among these geotechnologies, remote sensing (RS) has been widely used in agriculture. Through aerial imaging with remotely piloted aircraft, agricultural monitoring can be carried out, observing crop health and biophysical characteristics (plant height, productivity, etc.). Thus, this study aimed to monitor the spectral behavior and biophysical characteristics of corn cultivation in relation to temporal variability and nitrogen doses. The study was conducted at the experimental area of the Federal Technological University of Paraná (UTFPR), Santa Helena campus, where corn was cultivated. The experimental design was randomized complete blocks (RCB) with four treatments (0, 40, 80, and 120 kg ha-1 of urea) and four replications. The variables analyzed included biophysical characteristics of corn (plant height, stem diameter, first ear insertion height, number of rows per ear, ear length, number of grains per row, grain moisture content, and productivity), spectral bands (blue, green, and red), and vegetation indices (GLI - Green Leaf Index, VARI - Visible Atmospherically Resistant Index, VEG - Vegetation Index, and GRVI - Green-Red Vegetation Index). The monitoring of spectral behavior was carried out at twelve different times, through aerial imaging, from sowing to harvest, generating vegetation indices. Descriptive analysis, Pearson correlation, regression analysis, box plot, normality test, and analysis of variance (ANOVA) were performed for statistical analysis. For significant data according to the F-test, mean comparison tests were conducted: Kruskal-Wallis (non-parametric data) and Tukey (parametric data). It was observed that plants that absorb more nitrogen have darker leaf colors and higher values of vegetation indices, indicating greater crop health. It was concluded that the best date for spectral monitoring of different nitrogen doses in corn cultivation is in the week of mapping 5, when corn is in the V5-V6 growth stage.