Relationship Between Vegetation Indices, Nutrients Content, and the Biomass Production of Brachiaria (Brachiaria ruziziensis)

Abstract

ABSTRACT The aim of this study was to evaluate the use of a hyperspectral sensor to generate vegetation indices (VIs), which were correlated with the content of macro and micronutrients and the production of dry biomass of Brachiaria ruziziensis submitted to treatments with mining coproducts. The treatments were arranged in double factorial scheme, randomly assigned with five repetitions and placed into pots inside a greenhouse. The factors evaluated were type of input and soil class (Arenosol and Ferralsol). The inputs were limestone mining coproducts applied in two different ways, isolated and composed. After incubation for 140 days, brachiaria seeds were sowed. 40 days after sowing, the foliar spectra were collected, and so were the leaves for further analysis of the contents of macro and micronutrients, as well as the production of shoot dry biomass (SDM) of the plants. The application of the mining coproducts allowed the availability of great part of the nutrients analyzed, which led to an increase in brachiaria SDM. The increase in SDM, consequently caused physiological and structural alterations in the plant, in which, affect the VIs. The use of broadband VIs allowed a strong correlation (>0.5) with SDM, calcium (Ca), and copper (Cu). The narrowband VIs showed a strong correlation (>0.5) with Ca and Cu. This study confirms that the VIs correlate with agronomic attributes, such as SDM and with macro and micronutrients content in brachiaria.