Winter Wheat Canopy Temperature at Grain Filling Correlates to Yield in the Texas High Plains.

Wheat breeding has improved drought tolerance over the years. However, our knowledge on drought tolerance in relation to the canopy temperature (CT) and grain yields is limited. A three-season wheat field study ending 2012, 2015, and 2016 was conducted at Bushalnd, Texas to investigate the relationship between canopy temperature depression (CTD) during the mid-grain filling and yield. For each season, 20 elite wheat genotypes were grown under dryland condition, and the CT was measured by Smart Crop wireless IRT sensors every 15 minutes continuously for 12-15 days during the mid-grain filling. Among the 20 genotypes, 14 genotypes that were grown in all three years were included for CTD and yield comparison. There was a genotypic variation for CTD regardless of time of the day; however, the variation was more evident during the day time (10:00 -18:00 h), with the smallest CTD being at 14:00-15:00 h. In a dry season in 2012, Dumas, TAM 112, and TAM 304 had greater CTD (cooler canopy) than other genotypes. In two wet/ near-normal seasons (2015 and 2016), Duster, TAM 110, TAM 111, TAM 112, TAM 105 had greater CTD. There was a significant (P < 0.05) linear relationship between grain yield and day-time CTD. Study suggested that greater day time CTD at mid-grain filling may be a good indicator of greater drought tolerance and yield under dryland conditions. This knowledge may help breeders to conduct high-throughput field phenotyping in large breeding populations.