Graphical Abstract and Lay Summary The SPAD value is directly proportional to the nitrogen nutrition of crops. By analyzing the SPAD value, the growth status of plants can be understood, agricultural production management measures can be adjusted in a timely manner, and crop growth and development can be optimized. In this study, a widely used feature extraction method was introduced in finance and stock markets, namely MF‐DFA, to extract multifractal features of cotton canopy spectra, and introduced vegetation index for feature fusion. A hype...
