Addressing the challenge of combined heat and drought stress for cereal production

Chisaka, A. (2026) Addressing the challenge of combined heat and drought stress for cereal production. PhD thesis, University of Reading. doi: 10.48683/1926.00130857

Abstract/Summary

The effects of drought and heat stress on wheat (Triticum aestivum L.) yield are likely to worsen with climate change. Exogenous application of compounds that augment the natural plant hormones could help reduce the impacts of individual and combined stress in farming systems. This study investigated the effects of applying two novel compounds, quinabactin, an abscisic acid (ABA) analogue, and anisiflupurin, a cytokinin oxidase/dehydrogenase (CKX) inhibitor, on wheat response to drought, heat stress and their combination. A systematic review and meta-analysis were used to quantify the effects of drought, heat, and combined stress on wheat yield and yield components. The results revealed that, on average, combined stress causes greater yield losses of 49% compared to 22% and 27% for individual drought and heat stress, respectively. In experiments conducted over three years using the spring wheat variety Mulika, physiological, reproductive, and transcriptional responses were evaluated under progressive drought and heat stress imposed at the booting or anthesis. Quinabactin and anisiflupurin were applied at a concentration of 100 mg L-1 as a preventative or curative measure. Both compounds minimised the impacts of drought, heat and combined stress. The mechanisms by which quinabactin regulates wheat response include reduced transpiration and conserved soil moisture, improving water use efficiency, but with potential trade-offs on photosynthesis, leaf temperature, grain weight. whereas Anisiflupurin enhanced stomatal conductance, photosynthetic efficiency, tissue hydration, grain set, and grain weight per spike, supporting reproductive success under stress. Transcriptome profiling revealed that anisiflupurin upregulated genes associated with water and heat stress responses, cytokinin biosynthesis, zeatin metabolism, and photosynthesis, while quinabactin reduced the number of genes encoding heat shock proteins under heat and combined stress. The novel compounds have the potential to mitigate the impacts of combined drought and heat stress on wheat production in a timely manner, thereby strengthening global food security.

Item Type	Thesis (PhD)
URI	https://centaur.reading.ac.uk/id/eprint/130857
Identification Number/DOI	10.48683/1926.00130857
Divisions	Life Sciences > School of Agriculture, Policy and Development
Date on Title Page	September 2025
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