Influência do solo de fundo e da geometria da radiação na resposta espectral da cultura do feijão / Soil background and radiation geometry influence on spectral response in bean crop

AUTOR(ES)
DATA DE PUBLICAÇÃO

1994

RESUMO

The objective of this study is to understand the relationships among the NDVI (Normalized Difference Vegetation Index), the PVI (Perpendicular Vegetation Index) the SAVI (Soil Adjusted Vegetation Index) and the illumination geometry, the view angle geometry and the soil background. In order to observe the influence of these parameters, we setup a field experiment in the municipality of Pindamonhangaba (São Paulo State); using beans planted in N-S direction. The experiment consisted of the interaction of three factors times three repetitions. The factors considered were: three soil types spectrally different (Latossolo Roxo, Sand, and Latossolo Série Pinda), four radiometric acquisition times (at 10:00, 11:00, 12:00 and 13:00 o clock) two zenithal viewing angles (O and 30°). The result of the factorial interaction of these factors was: 24 factorial treatment and three repetitions. During the growth cycle of this culture, eleven radiometric campaigns were made with the Specton SE-590 spectroradiometer. Based on the calculated reflectance factor, TM-bands 3 (630 to 690nm) and 4 (760 to 900 nm) were simulated, and afterwards also the vegetation indices. The analysis of the factorial variance was performed using four characteristic growth stages of this culture. We observed that the soil types were a significant factor at these three indices. The variation of the viewing geometry did not show any significant change and the illumination geometry (variation of the solar angle) until the canopy, had a coverage of 100% of the soil. As for the relationship among the agronomic parameters and the vegetation indices, the NDVI was the index that presented the best determination coefficient (R2 = 0,99) with the parameters Leaf Area Index and Phytomass. Nevertheless, NDVI showed a tendency to saturation of those IAF values greater than two. The parameter Percentage of Vegetation Coverage was the worst to demonstrate the development of the canopy.

ASSUNTO(S)

leaf area index feijão radiometers solos farm crop índice de area foliar índice de vegetação agricultura background radiation radiometria soils vegetative index

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