Determination of biomass production of cotton using satellite images and spectral indexes

Abstract

The present study aimed to evaluate the mutual dependence between the spectral behavior in the cotton canopy, the leaf area index and biomass production. The study took place, in field conditions, under irrigation, in the Busato I Farm in the city of São Desidério-BA. The 10 samples for biomass determination were taken at intervals of approximately 15 days, collecting five consecutive plants contained in 0,45m2. The designated goods MOD09GQ and MOD13Q1 were used, where you got the vegetation indices NDVI and SAVI. To calculate the Leaf Area Index three methods were tested. The accumulation of biomass was estimated by two models and these were evaluated by correlation coefficients (r), accuracy (d) and also the index (c). The maximum values for NDVI, SAVI, and total dry matter production were 0.903, 0.717 and 1200g.m-2, respectively, at 90 days after emergence. The maximum leaf area index was found at 60 days after emergence. The highest growth rate of the culture was found at 80 days after emergence and 55% of the final dry matter were flower buds. The VIs were shown to be effective for obtaining the LAI, as well as the models that bring the radiation photosynthetically active if showed consistent, because they achieved reliability values considered excellent, and correlation coefficients and higher than 90% accuracy.