Fig. 5. Coefficients of determination (r²) vs. wavelengths for the relationships between cotton leaf N concentration and (A) leaf reflectance at all wavelengths (400 to 2500 nm) and leaf reflectance ratios of (B) R₅₁₇/R_i and (C) R₇₀₁/R_i for the 2001 N study. The r² values were based on a linear model, and data were pooled across the four N treatments, five sampling dates, and three replications (n = 60). Wavelengths with the greatest r² values are presented in the figure. Leaf N concentrations were expressed on both dry weight (DW) and leaf area basis.