Application of Relative Green Red Vegetation Index (rGRVI) Obtained by UAV and Image Analysis for Evaluation of Degree of Northern Leaf Blight and Southern Leaf Blight in Maize (Zea mays L.).

Abstract

A camera equipped UAV (drone) combined with image analysis was used for quantifying disease progression of northern leaf blight (NLB) and southern leaf blight (SLB) in maize. Early in the infection process when lesions were small, the correlation between a breeder’s rating and the relative Green Red Vegetation Index (rGRVI) in both NLB and SLB resistance was low. However, rGRVI showed a high correlation with the breeder’s rating for both NLB and SLB after lesions became larger as the disease progressed. In addition, calibration curves were prepared with standard maize varieties resulting in rGRVI estimates that correlated highly with the breeder’s rating. Thus, it was suggested that NLB and SLB resistance can be evaluated using rGRVI as an index and was more efficient than traditional scoring methods and can increase the number of varieties evaluated.