Fig. 7. Linear regression of cotton leaf chlorophyll with corresponding reflectance values at wavelengths of 551 (R₅₅₁) and 708 (R₇₀₈) nm and two reflectance ratios (R₅₅₁/R₉₁₅ and R₇₀₈/R₉₁₅) that had the greatest r² values with chlorophyll. Data were pooled across studies, treatments, replications, and sampling dates (n = 76 in 2001, n = 156 in 2002). Chlorophyll in 2001 was measured using a SPAD-502 chlorophyll meter. MC, mepiquat chloride.