Índice de área foliar e estresse hídrico da cana-de-açúcar em função de variáveis climáticas e dados orbitais
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2015-06-03
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Universidade Federal de Goiás
Resumo
Spectral information obtained by satellite imagery is well related to agronomic variables
and can be used to monitor sugarcane growth and their responses to changes in
environmental conditions of cultivation in large areas. This study is aimed to establish
relationships between orbital data in the spectral ranges of the thermal and active
photosynthetic radiation of Landsat-8 satellite with data observed with the leaf area index
field (LAI), plant height, number of green leaves, and leaf temperature in plots planted
with sugarcane, CTC-04 genotype, in a production cycle in sugarcane plant stage in Santo
Antônio de Goiás-GO in the 2013/14 crop year. The first study aimed to calibrate a model
to measure the temporal variation of the sugarcane LAI from the Normalized Difference
Vegetation Index (NDVI) obtained from satellite Landsat 8’s surface reflectance images. It
was conducted and the correlation between the LAI collected in the field and the NDVI
with and without application of atmospheric correction. The corrected model showed the
best relationship with field data. The application of the spectral model was efficient to
monitor LAI over a sugarcane plant cycle. The results suggest that the NDVI-LAI
relationship may vary during the production cycle of sugarcane due to variations in growth,
development, and environmental conditions. Spectral variable NDVI with atmospheric
correction was highly correlated (R² = 0,83) with LAI but the relationship proved to be
affected by the NDVI saturation point at high values of LAI observed in the field. The
second study aimed to evaluate the applicability of surface temperature (LST) obtained
from the thermal bands of the Landsat-8 in correlation with the leaf temperature of
sugarcane, to establish relationships able to detect water stress remotely through the
images, in the occurrence period of drought throughout the year production in rain fed crop
in the Cerrado region. The results showed that LST, despite having low direct association
with the leaf temperature, has the potential of monitoring water stress in sugarcane within
the Cerrado region, since the simulation of the difference between LST and the air
temperature accompanies the spread between the leaf temperature and the air, the
dynamics of soil water balance and changes in crop growth rates that occur in response to
water stress.
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PEREIRA, R. M. Índice de área foliar e estresse hídrico da cana-de-açúcar em função de variáveis climáticas e dados orbitais. 2015. 94 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2015.