ELABORAÇÃO E VALIDAÇÃO DE ESCALA DIAGRAMÁTICA PARA QUANTIFICAÇÃO DE COMPLEXOS FITOSSANITÁRIOS NA SOJA (Glycine max)

Abstract

Soybean cultivars in the field in different environments express potential and are affected in simultaneous and differential ways by numerous sanitary plant agents, which explain significant yield losses. The objective of this work was the creation and validation of a diagrammatic scale for quantification of sanitary plant complexes in the field. In the 2019/2020 season, leaflets were photographed in different cultivars and phenological stages, representing a range of leaf damage. The real severity was measured with the analysis of 110 images, where algorithms were built to determine the severity, shape, size, confluence, color, among others. They were discriminated and categorized as patterns of biotic and abiotic diseases. The scale considered the minimum and maximum severity limits observed in the field and the intermediate levels following logarithmic increments, with a lower limit of 0% and an upper limit of 87% of the injured area. Comparing observed and actual measured severity, and linear regression coefficients showed that accuracy and precision were considerably satisfactory according to the significance levels of the statistical program R. The coefficient of determination of all evaluators increased, reaching 0.91, the error of the evaluators of phytosanitary severity, with and without the use of the scale resulted in significant improvements in 100% of the evaluators used.