Sharma, Dew Kumari6; Fernández, Juan Olivares3; Rosenqvist, Eva7; Ottosen, Carl-Otto4; Andersen, Sven Bode8
1 Section for Plant and Soil Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet2 Section for Crop Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet3 Universidad Politecnica de Madrid (UPM)4 Institut for Fødevarer - Planter, Fødevarer og Klima5 Department of Agriculture & Ecology, Plant and Soil Science, Department of Agriculture & Ecology, Faculty of Life Sciences, Københavns Universitet6 Section for Plant and Soil Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet7 Section for Crop Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet8 Department of Agriculture & Ecology, Plant and Soil Science, Department of Agriculture & Ecology, Faculty of Life Sciences, Københavns Universitet
The genotypic response of wheat cultivars as affected by two methods of heat stress treatment (treatment of intact plants in growth chambers versus treatment of detached leaves in test tubes) in a temperature controlled water bath were compared to investigate how such different methods of heat treatment affect chlorophyll fluorescence parameters. A set of 41 spring wheat cultivars differing in their maximum photochemical efficiency of photosystem (PS) II (Fv/Fm) under heat stress conditions was used. These cultivars were previously evaluated based on the heat treatment of intact plants. The responses of the same cultivars to heat stress were compared between the two methods of heat treatment. The results showed that in detached leaves, all of the fluorescence parameters remained almost unaffected in control (20°C at all durations tested), indicating that the detachment itself did not affect the fluorescence parameters. In contrast, heat induced reduction in the maximum photochemical efficiency of PSII of detached leaves occurred within 2h at 40°C and within 30min at 45°C, and the response was more pronounced than when intact plants were heat stressed for three days at 40°C. The proportion of total variation that can be ascribed to the genetic differences among cultivars for a trait was estimated as genetic determination. During heat treatment, the genetic determination of most of the fluorescence parameters was lower in detached leaves than in intact plants. In addition, the correlation of the cultivar response in intact plants versus detached leaves was low (r=0.13 (with expt.1) and 0.02 with expt.2). The most important difference between the two methods was the pronounced difference in time scale of reaction, which may indicate the involvement of different physiological mechanisms in response to high temperatures. Further, the results suggest that genetic factors associated with cultivar differences are different for the two methods of heat treatment.
Journal of Plant Physiology, 2014, Vol 171, Issue 8, p. 576-586