The frost occurence is a climatic factor that causes negatives consequences to a less or higher degree in all steps of forestry production, and can even be characterized as a limiting factor in commercial plantations in southern Brazil. Through remote sensing and espectroradiometry techniques, its possible to obtain information about the plants stress conditions, caused by the intense cold and the ice formation. The aim of this paper was to evaluate and analyze reflectance curves in the spectral range 400-2000ηm, from seedlings of Pinus taeda exposed to frost incidence in the Nursery of Universidade Federal de Santa Maria in four harsh winter day. The radiometric measurements were made with spectroradiometer FieldSpec\uae3connected to RTS-3ZC unit (integrating sphere). Statistical tests (ANOVA and Tukey), showed the significant differences existence in reflectance curves between measurement periods. Over the time there was a significant increase in reflectance factor in the visible range, which shows the loss of photosynthetic pigments. The disintegration of mesophyll is also evidenced by the substantial increase in reflectance in the near infrared region. In this way, this technique was capable of detecting changes in the physiology of leaves submitted to stress caused by frost. What enhances the use of this tool in planning forest activities subject to losses by this phenomenon.Pages: 3171-317
