Abstract
Developing cultivars with improved adaptation to drought and heat stressed environments is a priority for plant breeders. Canopy temperature (CT) is a useful tool for phenotypic selection of tolerant genotypes, as it integrates many physiological responses into a single low-cost measurement. The objective of this study was to determine the ability of CT to predict grain yield within the flow of a wheat breeding program and assess its utility as a tool for indirect selection. CT was measured in both heat and drought stressed field experiments in northwest Mexico on 18 breeding trials totaling 504 spring wheat lines from the International Maize and Wheat Improvement Center (CIMMYT) Irrigated Bread Wheat program. In the heat treatment, CT was significantly correlated with yield (r = −0.26) across all trials, with a maximum coefficient of determination within the individual trials of R2 = 0.36. In the drought treatment, a significant correlation across all trials was only observed when days to heading or plant height was used as a covariate. However, the coefficient of determination within individual trials had a maximum of R2 = 0.54, indicating that genetic background may impact the ability of CT to predict yield. Overall a negative slope in the heat treatment indicated that a cooler canopy provided a yield benefit under stress, and implementing selection strategies for CT may have potential for breeding tolerant genotypes.
Highlights
Canopy temperature (CT) is a useful indicator of crop water status [1] and has potential as a tool for indirect selection of genotypes tolerant to drought and heat stressed environments [2]
Comparison of the two check cultivars across all trials found RoelfsF2007 to outperform Waxwing, yielding 6.0 tons ha−1 and 5.4 tons ha−1 in the drought and heat stress treatments, respectively, compared to 5.2 tons ha−1 and 5.0 tons ha−1 for Waxwing (Table 1)
Cooler CT was favorable for higher yield this association was stronger and more consistent under heat stress
Summary
Canopy temperature (CT) is a useful indicator of crop water status [1] and has potential as a tool for indirect selection of genotypes tolerant to drought and heat stressed environments [2]. CT has been shown to correlate with these physiological traits under field conditions [6,7,8,9] and integrates them into a single low-cost diagnostic measurement that has potential for selection of tolerant parental genotypes or early generation breeding lines [2,8]. Lopes and Reynolds [13] found similar broad sense heritability for a diverse set of 294 spring wheat lines (H2 = 0.38) and a set of 169 sister-lines (H2 = 0.34) across well-watered, drought stressed and heat stressed environments in northwest Mexico
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