Spectral behavior of Eucalyptus globulus atacadas por Mycosphaerella spp. nas regioes do visivel e do infravermelho proximo do espectro eletromagnetico

The study aims to analyze the spectral behavior of leaves of Eucalyptus globulus attacked in four different severity levels by Mycosphaerella spp. in different positions in the canopy of the tree in the four seasons, considering two regions of the electromagnetic spectrum: visible and near infrared. The plant material was collected in all seasons, in different positions in the tree (base, middle and top of the canopy extract). In the laboratory, leaves were classified into four levels of severity (healthy, little, medium and heavy fire) and then made measurements of spectral reflectance measured with a spectroradiometer. The spectral behavior of Eucalyptus globules leaves is characteristic according to the severity degree of the disease, differing primarily in the other high levels of infection by Mycosphaerella spp. and differ mainly of healthy leaves and leaves which are little attacked, in both regions of the electromagnetic spectrum, this behavior occurs for different treetop positions and climate seasons, varying the amount of reflected energy. It is concluded that the reflectance of the Eucalyptus globules leaves attacked by Mycosphaerella spp. differs according to the position in the tree crown and the weather station when they were collected and to the advanced levels of disease severity. Keywords: epidemiology; severity level; spectroradiometry; leaf reflectance. O trabalho tem como objetivo analisar o comportamento espectral de folhas de Eucalyptus globulus atacadas em quatro diferentes niveis de severidade pelo fungo Mycosphaerella spp. em diferentes posicoes na copa da arvore, nas quatro estacoes climaticas, considerando duas regioes do espectro eletromagnetico: visivel e infravermelho proximo. Foram realizadas coletas de material vegetativo em todas as estacoes climaticas, em diferentes posicoes na arvore (base, meio e extrato superior da copa). Em laboratorio, as folhas foram classificadas em quatro niveis de severidade (sadio, pouco, medianamente e muito atacado) e posteriormente efetuadas as medidas de reflectancia espectral com auxilio de um espectrorradiometro. O comportamento espectral das folhas de Eucalyptus globulus e caracteristico de acordo com o nivel de severidade da doenca, diferindo dos demais principalmente em altos niveis de infeccao por Mycosphaerella spp. e diferenciam-se principalmente de folhas sadias e de folhas pouco atacadas, em ambas as regioes do espectro eletromagnetico, esse comportamento ocorre para as diferentes p