Fig. 9

Leaf number required to fill measurement window, and leaf position corresponding to leaf age, affected reflectance at different wavelengths. Effects of number of leaves (one or two) used for reflectance measurements in linear model: a Model 2 (with all samples), b Model 3 (with only UT-WT samples) in Field_AZ. Shaded areas indicate the range of reflectance for samples measured with 1 leaf (light orange), versus 2 leaves placed side-by-side to form one layer (blue), which was done when needed to fill the measurement window in Field_AZ due to leaves being generally narrower in that experiment. The dashed pink line shows the p-value for 1- vs. 2-leaf measurements. The solid pink lines indicate adjusted p-values. c Effects of leaf position in the linear model in Field_UT. Shaded areas indicate the range of reflectance for yellow: younger (Leaf 1), orange: intermediate (Leaf 2), and blue: older (Leaf 3) leaves. The dashed pink line shows the p-value for effects of the leaf position, solid pink line after adjustment. P-values from the post-hoc pariwise comparison. The dashed yellow line shows the p-values of Leaf 1 and Leaf 2 measurements, blue line Leaf 1 vs. Leaf 2, orange line Leaf 2 vs. Leaf 3. Solid colored lines are the p-values after adjustment