LIMA, Claudinei Paulo de et al. Uso de índices de reflectância das folhas para avaliar o nível de nitrogênio em grama-bermuda. Cienc. Rural [online]. 2012, vol.42, n.9, pp. 1568-1574. Epub 31-Jul-2012. ISSN 0103-8478. http://dx.doi.org/10.1590/S0103-84782012005000062.
Study uses chlorophyll meter and digital image to evaluate N concentration in Bermuda grass
Researchers from Faculdades Integradas de Ourinhos (FIO), Ourinhos, São Paulo, from Universidade Estadual Paulista (UNESP), Botucatu, São Paulo, and from Universidade Estadual de Goiás (UEG), Goiás, Brazil, demonstrated that leaves reflectance are related to the quantity of Nitrogen in Bermuda grass. The study was published in Ciência Rural journal, v.42, n.9, of September, 2012.
To evaluate reflectance, researchers used a chlorophyll meter and digital image analysis. With these procedures, hue (H), dark green color index (DGCI) and the intensity of green color were obtained. These variables presented positive correlation with N concentration and the soil cover rate of Bermuda grass.
According to researcher Claudinei Paulo de Lima, results reported are the first indices of nutritional evaluation in the N in Bermuda grass. They may serve as indicators during application of nitrogen fertilizer and thereby increase the efficiency of N applied. "When the contents of the area to be fertilized are already close to the reference values obtained, fertilization may be delayed or even canceled," he says.
The innovation of the research is to use leave reflectance of the grass to estimate the concentration of nitrogen, using color meter of grass, chlorophyll, and digital image analysis. According to Claudinei, studies have evaluated the nitrogen level in other species, but the use of chlorophyll meter and digital image in conditions of Brazilian climate was still unheard of.