Effects of post-flowering heat stress on chlorophyll content and yield components of a spring wheat diversity panel

Authors: FU, JIANMING - Kansas State University; JAGADISH, KRISHNA - Kansas State University; Bowden, Robert

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/24/2022
Publication Date: 5/26/2022
Citation: Fu, J., Jagadish, K., Bowden, R.L. 2022. Effects of post-flowering heat stress on chlorophyll content and yield components of a spring wheat diversity panel. Crop Science. https://doi.org/10.1002/csc2.20778.
DOI: https://doi.org/10.1002/csc2.20778

Interpretive Summary: Wheat is relatively susceptible to high temperature stress during the grain filling period. Heat stress typically accelerates chlorophyll loss and results in shriveled kernels. In this study we screened a panel containing 254 diverse spring wheat lines for ability to retain leaf chlorophyll content and seed weight under heat stress conditions. Significant genetic variation was demonstrated for both traits. Chlorophyll retention was positively correlated with seed weight. The best lines were identified as potential donors for higher heat stress tolerance in wheat breeding programs.

Technical Abstract: High temperature has been a major limiting factor for wheat productivity and will become a significant driver of yield loss as global warming progresses. Many wheat-growing regions worldwide experience terminal heat stress during the grain-filling period, resulting in grain yield reduction. A sustainable solution to mitigate heat stress-induced damage is to develop heat-tolerant cultivars. To achieve this, identifying tolerant lines is essential to incorporate heat stress resilience into commercial varieties. Our working hypothesis is that retaining chlorophyll content during post-flowering heat stress will reduce yield losses. In this study, we evaluated the terminal heat stress tolerance of 254 diverse spring wheat lines from North American and Australian wheat breeding programs in two independent experiments under controlled environments. Significant genetic variation was observed for post-stress chlorophyll content and yield components. Total grain weight and single grain weight were significantly correlated with chlorophyll content under heat stress. The reduction in total grain weight was contributed more by the reduction of the single grain weight than by the grain number under heat stress. A highly tolerant line, Otis, retained 79.2% chlorophyll content relative to control, and also recorded 55% greater chlorophyll content than the average of all 254 lines, at the end of 16 days of severe heat stress treatment. Mapping populations are being developed using Otis, with an aim to identify the genetic basis of chlorophyll retention under terminal heat stress. Resilient wheat lines identified with high grain weight under stress will serve as useful resources to abiotic stress breeding programs.