Evaluation of wheat canopy cover using NDVI in large areas of Iran

To studies a suggested method for estimating fractional green canopy cover (FGCC or CC) from normalized difference vegetation index (NDVI) in Iran, a research project was carried out on four wheat farms in the large-scale region, in Fars and Khuzestan provinces during four growing seasons from 2015 to 2019. Two different image classification methods were used to provide the CCs of farms. In both methods, R²s were greater than 0.95 and NRMSEs were less than 0.15. A simple regression equation was constructed between CC and NDVI of 64 Landsat 8-Oli images with high accuracy from 2015 to 2018. The R²s of CC-NDVI equations were 0.84, 0.85, 0.88, 0.80 and 0.76 in Dezful, Omidieh, Darab, Zarghan and all sites together. The simple regression equation was used to simulate CC in 2018-2019 for validating the equation and had a good agreement with the measurements, especially in using the general equation of all sites. The p-values of the four equations were less than 0.03. As a suggested method, the CC-NDVI equation can be used to predict CC from NDVI as a low-cost and less time-consuming method in the study area to use in crop growth studies, crop growth models and crop growth management.