Validação do índice de área foliar e teor de água na copa estimados através de imagens sentinel-2 na cultura do milho (Zea mays L): estudo de caso do distrito de Vilankulo

Abstract

The knowledge of the crop status about its biophysical parameteres, such as leaf area index (LAI) and canopy water content (CWC) is a fundamental aspect to reach good yields. The measurement of biophysical parameteres by direct methods presents challenges such as spatial and temporal limitations besides of being distructives, So alghoritms based os sentinel-2 images has been developed for agricutural applications, including specific models for biophysical parameteres estimations. However, its application in conetest of non intensive crop systems requires a preview evaluation. Therefore the present research was developed with the perpurse of evaluating the applicability of sentinel 2 imagerie data for estimating biophysical parameteres on Maize crop. The study took place at the campus of Rural Development School (ESUDER) in an area of 0,41 ha with the genotip of maize Topo (KC9089), with the frequency of 5 days LAI and CWC were esimated using 10 m and 20 m resolution respectively, with 4 plots of 20 x 20 metters each. For the validations were employed direct methods which consisted on the usage of allometric measurements and the usage of LAI 2200C equipment. For CWC was employed the gravimetric method which consisted on obteining the difference between fresh and dry weight. Correlation tests were performed using IBM SPSS and were compared using determination coefficient (R 2 ) and the root mean square error (RMSE). For LAI, strong correlation (R 2 =0,67) was obtained between allometric measurements data and sentinel 2 estimations, which demonstrate the accuracy of Sentinel-2 data in the estimations of LAI, however, errors (RMSE = 1,4 m 2 /m 2 ) were obtained. For CWC the estimations by Sentinel 2 demonstrated an high correlation with the gravimetric method data (R 2 =0,72), however high erros (RMSE = 4,03 g/m 2 ) were obtained. Which showed an high underestimation of CWC estimated based on Sentinel-2 imagerie data.