Chlorophyll
Chlorophyll a and b were measured at 42 DAS, from the youngest fully extended leaf blade. Leaf samples were weighed and then placed in DMF for 72 h. Absorbance of the extracted pigments was measured using a spectrophotometer (UV-VIS recording spectrophotometer, UV-2401PC) at 645nm and 663nm. The photosynthetic pigment content was expressed in mg per gram-fresh weight leaf tissue (mg/g−1 FW), as adapted from (Kolotilin et al., 2007).