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Canopy temperature depression (CTD = air temperature [Ta] – canopy temperature [Tc]) has been used to estimate crop yield and to rank genotypes for tolerance to heat and drought, but when to measure CTD for breeding selection has seldom been addressed. Our objectives were to evaluate the suitability of CTD for the Texas High Plains environment and to determine optimal measurement times in relation to growth stage, time of day, and weather. Three years of CTD and weather data were used to assess regression models of grain yield in three wheat (Triticum aestivum L.) lines. Under dryland agriculture, long‐term mean CTD at noon and yield were correlated in 2000 and 2001. The relation of short‐term CTD readings to grain yield was highly variable. Poor correlation was associated with days of low solar irradiance, high wind speed, and rain events. Genotype effects on CTD were detected for all hours of day and night. Genotype × hour interaction was insignificant at night, suggesting that nighttime measurements may provide more stable conditions for CTD comparison among genotypes. In general, tree regression assessed grain yield from short‐term CTD measurements better than linear regression and suggested that the best times to measure CTD were 0900, 1300, and 1800 h. Tree regression models provided a heuristic interpretation of crop water status under different scenarios of soil water availability.

‘TAM 112’ (Reg. No. CV‐1101, PI 643143), a hard red winter wheat (Triticum aestivum L.) cultivar with experimental designation TX98V9628, was developed and released by Texas A&M AgriLife Research in 2005. TAM 112 is an F4–derived line from the cross U1254‐7‐9‐2‐1/TXGH10440 made at Vernon, TX, in 1992. U1254‐7‐9‐2 is a USDA–ARS germplasm line from the Plant Science and Entomology Research unit, Manhattan, KS, and TXGH10440 is a sibling selection of the cultivar TAM 110. TAM 112 is an awned, medium‐early maturing, semidwarf wheat with red glumes. It was released primarily for its excellent grain yield potential particularly in dryland environments of the southern Great Plains; resistance to stem rust (caused by Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn.), powdery mildew [caused by Blumeria graminis (DC.) E.O. Speer f. sp. tritici Em. Marchal], and greenbug [Schizaphis graminum (Rondani)]; and good milling and bread‐baking characteristics. Compared with existing hard red winter wheat cultivars at the time of release, TAM 112 is most similar to TAM 110 with respect to area of adaptation and disease and insect resistance, but it has significantly higher yield and better bread‐baking characteristics than TAM 110. Licensed to Watley Seed Company for marketing, TAM 112 is currently one of the most popular hard red winter wheat cultivars adapted to the dryland production system in the Texas High Plains and similar areas in the southern Great Plains.

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