Quantification of Leaf and Root Areas

Leaf area for each A. thaliana plant was calculated from the hyperspectral reflectance images. During preprocessing of the hyperspectral reflectance data (described below), all plant pixels in each image were identified. Leaf area was then calculated by multiplying the total number of plant pixels by the measured pixel area (0.000112 cm²/pixel).

To quantify root area, each plant was moved to a 1 L polycarbonate Nalgene container containing approximately 800 mL of basal medium. A black sheet of paper was placed behind the container; a ruler was placed next to the container; and a digital image was acquired using a Cannon EOS Rebel T2i DSLR camera. In ImageJ, the scale was set for each image using the ruler in the image, and it was then cropped to only contain the white roots with the black background. The cropped images were converted to binary, and root area was calculated using the Analyze Particles function in ImageJ.