Deeper roots associated with cooler canopies, higher normalized difference vegetation index, and greater yield in three wheat populations grown on stored soil water

Simple and repeatable methods are needed to select for deep roots under field conditions. A large-scale field experiment was conducted to assess the association between canopy temperature (CT) measured by airborne thermography and rooting depth determined by the core-break method. Three wheat populations, C306×Westonia (CW), Hartog×Drysdale (HD), and Sundor×Songlen (SS), were grown on stored soil water in NSW Australia in 2017 (n=196–252). Cool and warm CT extremes (‘tails’) were cored after harvest (13–32% of each population). Rooting depth was significantly correlated with CT at late flowering (r= –0.25, –0.52, and –0.23 for CW, HD, and SS, respectively, P