A chlorophyll meter was used to obtain SPAD values on the first and third fully expanded leaf. SPAD readings were taken at three locations: (a) approximately 2/3 down from the leaf tip, (b) the midpoint of each leaf blade, 30 mm apart, on one side of the midrib, and (c) approximately 1/3 of the way down from the leaf tip, respectively. SPAD readings were acquired weekly during growth until heading.