The inheritance of heat tolerance in wheat

Abstract

The frequency of extreme cold weather has decreased across most of Australia, while the frequency of warm weather has increased. These episodes of heat stress have been and continue to be a major threat to wheat production and grain quality by impacting morpho-anatomical, physiological and biochemical properties resulting in reduced plant growth and development and lower yield. This study explored the effects of heat stress on bread and durum wheats. Bread wheat was assessed by evaluating 20 genotypes across two years and two sowing dates in field and laboratory experiments. The field experiments were conducted in 2014 and 2015 at Narrabri to determine genotype tolerance to high temperature stress. Two sowing dates (May and July) were used to create a differential in temperatures. Irrigation was applied as required to avoid excessive drought stress and to model, as much as possible, the average yield for this location. Yield, physiological, phenological, grain quality and dough rheological properties were assessed each season. All field experiments took place at the University of Sydney’s Plant Breeding Institute, Narrabri NSW and dough rheological experiments were determined at Tamworth Agricultural Institute, Calala NSW. Late sowing was effective in identifying genotypes that tolerated heat stress and replicated actual farm conditions. Heat stress reduced grain yield between 4.3-5.5%, hastened plant development 26.8- 30.7%, reduced biomass accumulation between 2.6-4.9%, reduced seed size between 2.6-4% and increased flour protein between 5-18.3%. However, overall flour quality was reduced. Several genotypes had stable yield and quality and could be used for future breeding of heat tolerant bread wheat.