RELATIONSHIP BETWEEN NORMALIZED DIFFERENCE VEGETATION INDEX AND GREEN CANOPY COVER IN LEGUMINOUS CROPS

Abstract

The article presents the results of a study on the relationship and the possibility of mutual conversion between the normalized differentiated vegetation index (NDVI) and fractional green canopy cover (FGCC) in legumes. The purpose of the work is to provide proposals for models of mutual conversion between the vegetation indices. Materials and methods. The basis of the study was formed by the photographic materials of the leguminous crops, taken at different phases of growth and development on the fixed sites every 10 m of the experimental fields, obtained and automatically calculated to establish the percentage of green canopy cover in Canopeo mobile application. Experimental materials were obtained in 2021 in the experimental fields of the Institute of Irrigated Agriculture of NAAS and in 2016 in the experimental field of the AC "Radyanska Zemlya". Subsequently, the geotags and dates of shooting photographic materials were tied to the satellite NDVI values ​​obtained through the OneSoil AI platform for each of the studied crops (the difference in dates is up to 3 days). The established pairs of FGCC and NDVI for each crop were submitted for statistical analysis by polynomial regression. Statistical calculations and graphical work were performed in Microsoft Excel 365 spreadsheets. Results. It has been established that there is a close linear and nonlinear relationship between the FGCC and NDVI indices of the studied crops. The strength of the relationship is high, with a correlation coefficient in the range of 0.95-0.98 and a determination coefficient of 0.90-0.97. Polynomials of the second stage (nonlinear regression models) can be successfully used for mutual conversion between vegetation indices; the error in recalculation for most crops did not exceed 10 %. Conclusions. A high affinity between the normalized differential vegetation index and the percentage of green canopy cover in the leguminous crops (R2 within 0.90-0.97) has been proven. The closest relationship is observed for soybeans and beans compared to chickpeas and peas. Key words: peas, common beans, conversion, chickpeas, regression analysis, soybean.