Plant Breeding & Genetics Research Laboratory

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.

Heterosis plays an important role in switchgrass (Panicum virgatum L.) breeding. To identify superior clones for hybrid development through seasonal single cut, 10 crosses derived from ‘Alamo’ × ‘Kanlow’ and parents were evaluated. The experiment was planted in 2018 using a randomized complete block design with two replications at two locations in Tennessee: the East Tennessee Research and Education Center (ETREC), Knoxville, and the Plateau Research and Education Center (PREC), Crossville. The crosses and their parents were evaluated for biomass yield, plant height, and clonal mass in the fall of 2019 and 2020. The crosses were significantly different in biomass yield within and across locations (P ≤ .05). Average biomass yield of the crosses ranged from 7.1 to 8.7 Mg ha−1 at ETREC and from 10.0 to 11.8 Mg ha−1 at PREC. The crosses demonstrated an average of 46% mid-parent heterosis (MPH) and 24% high-parent heterosis (HPH) for biomass yield across the two locations. The MPH and HPH were 3 and −1.3% for plant height and 12 and 1% for clonal mass, respectively. Moderate to strong positive association was found between clonal mass scores and biomass yield at individual locations across years and across locations and years (r = 0.37–0.79, P ≤ .05). The association between biomass yield and plant height was inconsistent (r = −0.24 to 0.67, P ≤ .05). The findings of biomass yield heterosis in these crosses suggested the potential of hybrid cultivars for biomass yield improvement in lowland switchgrass.