Association of canopy temperature with agronomic traits in spring wheat inbred populations

Canopy temperature (CT) is considered a reliable proxy for stomatal conductance. Low CT values of plant canopies under water-limited conditions are associated with high transpiration indicating plants’ drought tolerance. Many U.S. Pacific Northwest (PNW) adapted wheat ( Triticum aestivum L.) cultivars lack stress-adaptive traits resulting in poor performance in drought environments. This study aims to identify the stress-adaptive traits by evaluating the CT in spring wheat populations across different soil moisture conditions in the PNW. An infrared thermometer was used to estimate the CT in two families of recombinant inbred lines, ‘Alpowa’ × ‘Express’ (AE population) and ‘Hollis’ × ‘Drysdale’ (HD population), in rainfed and irrigated environments of the dryland PNW in 2011 to 2013. Higher reductions in grain yield up to 170%, spike length up to 25%, and spikelets spike −1 up to 19% were observed in a rainfed environment compared to the reductions in an irrigated environment. A significant variation in CT was observed in both AE and HD populations. With 1 °C increase in CT at the anthesis stage, grain yield was lowered up to 38 g m −2 . Low CT was associated with high grain yield and agronomic traits in both wheat populations ( r = − 0.18 to − 0.55, P ≤ 0.05). The highest association between CT and grain yield was observed at anthesis ( r = − 0.47) and milking ( r = − 0.38) stages ( P ≤ 0.001). Our results show that screening for low CT during terminal wheat growth stage is an effective strategy for improving the selection of new drought-tolerant wheat varieties in the PNW.