|Evett, Steven - Steve|
Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/21/2001
Publication Date: 10/21/2001
Technical Abstract: Canopy temperature depression (CTD) has been proposed as a useful tool for revealing genotypic variation for crop tolerance to heat and drought stress. The availability of inexpensive infra-red thermometers (IRT), when connected to standard dataloggers, makes it now feasible to monitor diurnal patterns of CTD in fields. This improves our ability to detect genotypic variation. However, different applications may require different sampling procedures. For example, breeding programs will have too many entries to continuously monitor for CTD and must use other methods, such as periodic sampling with a hand-held IRT gun, aerial photography or satellite imagery. Such programs need to determine the optimum time of sampling that will give the largest probability of detecting CTD variation. Here we use nearly continuous CTD readings, obtained from three wheat lines previously distinguished for yield response to water availability to assess the optimal time of sampling to distinguish genotypic response. Measurements of CTD were taken during 2000 and 2001 at Bushland, Texas. Significant differences for CTD among the genotypes were recorded in both years. Significant influences of time of the day, day of the year, and year on canopy temperatures were also identified. A consistent ranking of the genotypes, with less error due to the environment, was observed when sampling predawn.