Temporal Behavior of Ndvi Measured With an Active Optical Sensor for Different Varieties of Sugarcane

Abstract

Active optical sensors are a new approach for site specific nitrogen management on real time and they have been successfully used on grain crops. This work consisted in evaluating the behavior of the Normalized Difference Vegetation Index (NDVI) using a commercial active optical sensor on 28 sugarcane varieties, as well as analyzing the temporal behavior of this index for each variety throughout the initial 150 days of their productive cycle. The NDVI data was collected with 90, 120 and 150 days after planting (DAP). A descriptive statistical analysis of the data was performed and a Tukey test was applied to contrast the NDVI means. Results indicated that the varieties interfere in the NDVI readings and, in general, the readings with 90 DAP were different from those with 120 and 150 DAP, tending to stabilize along time for each variety.Keywords: Precision Agriculture, NDVI, Remote Sensing. RESUMOSensores óticos ativos são uma nova opção para o manejo da aplicação localizada de nitrogênio em tempo real e têm sido empregados com sucesso em culturas de grãos. Este trabalho consistiu em avaliar o comportamento do NDVI (Normalized Difference Vegetation Index) obtido com um sensor ótico ativo comercial, em 28 variedades de cana-de-açúcar, assim como analisar o comportamento temporal deste índice para as diferentes variedades ao longo dos primeiros 150 dias de seu ciclo. Os dados do NDVI foram coletados longo dos primeiros 150 dias de seu ciclo.

Sugarcane response to nitrogen rates, measured by a canopy reflectance sensor

“…This result contrasts with the necessity of specific calibrations, as suggested by Frasson et al (2007), as a function of the morphological differences among the different varieties and their consequences in spectral behavior. Therefore, the factors that seem to influence canopy sensor readings the most are crop vigor and canopy volume, usually dependent on edaphic and climate conditions, rather than on factors associated with the cultivated variety, such as leaf color or plant architecture.…”

“…However, the lowest fitting in the first and second experiments could be a reflection of the presence of varieties with different production potentials that could have responded in different ways to climate, soil, and management conditions throughout the crop cycle, resulting in different crop vigor and canopy volume in the same field. According to Frasson et al (2007), the abovementioned statement on specific calibration sounds reasonable.…”

Optical Sensors Applied in Agricultural Crops

“…And that is what makes the sensors to be promising while evaluating nitrogen stress. Many studies were realized to estimate nitrogen deficiency in corn [3], wheat [20], edible beans [21], cotton [22], citrus [23], barley [24] and sugarcane [25]. These authors showed great potential to use sensors to estimate nitrogen content in crops.…”