Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2018
Publication Date: 3/28/2018
Citation: Burke, J.J., Emendack, Y., Hayes, C.M., Chen, J. 2018. Genetic diversity in the environmental conditioning of two sorghum (Sorghum bicolor L.) hybrids. American Journal of Plant Sciences. 9:817-831.
Interpretive Summary: It is difficult to visually detect how well a sorghum plant responds to cool or warm environments. This study reports the findings of the stress responses of two commercial sorghum cultivars using a procedure developed by an USDA-ARS scientist. The two cultivars were grown in either a cool or warm environment under controlled conditions and their metabolic responses compared using a stress bioassay. The results observed under controlled conditions were compared to the responses of these cultivars to field water and temperature stresses. The findings showed that the stress bioassay could detect genetic differences under both controlled and field conditions.
Technical Abstract: Sorghum metabolism continually adapts to environmental temperature as thermal patterns modulate diurnally and seasonally. The degree of adaptation to any given temperature may be difficult to determine from phenotypic responses of the plants. The present study was designed to see if the efficiency of quantum yield of photosystem II could be used as a measure of how well leaf tissue metabolism was able to withstand a prolonged respiratory demand caused by elevated temperatures. The efficiency of quantum yield values of Pioneer 84G62 and Northrup King KS585 commercial sorghum hybrids showed that when the hybrids were grown in a 28/20°C day/night cycle in the greenhouse or the field, Pioneer hybrid 84G62 withstood subsequent elevated thermal challenges better than Northrup King KS585. The same hybrids grown in a 39/32°C day/night cycle showed similar efficiency of quantum yield values when thermally challenged. Water-deficit stress increased the heat resistance of the tissue raising the efficiency of quantum yield of both lines to the same level. Upon recovery from the water deficit stress the differential efficiency of quantum yield values between the two lines re-appeared. The data provided in this study suggests a metabolic advantage of Pioneer 84G62 to environmental thermal challenges compared with the Northrup King KS585.