Mr Dongyu Wu1, Dr Rebecca Thistlethwaite1, Dr Anowarul Bokshi1, Professor Richard Trethowan1, Prof. Daniel Tan1
1The University of Sydney, Narrabri, Australia
Biography:
Dongyu Wu (Justin) is a 4th year Honours student enrolled in a Bachelor of Science/ Bachelor of Advanced Studies (Agriculture) at the University of Sydney. He conducted his honours research at the Plant Breeding Institute in Narrabri, NSW.
Abstract:
Australian agriculture faces increasing challenges due to global warming, with a critical need to understand wheat heat tolerance mechanisms for breeding heat tolerant varieties. An experiment was conducted to investigate the genetic variation in wheat in response to high-temperature stress under ambient and elevated CO2 levels, testing two hypotheses: 1) Under ambient temperature, wheat yields will increase at elevated CO2 (800 μL L-1) compared with ambient CO2 (400 μL L-1) conditions, and 2) Elevated CO2 will moderate the effects of heat stress during grain filling and sustain yield compared to heat stress under ambient CO2 conditions. Wheat plants were grown in a controlled glasshouse environment at ambient or elevated CO2 levels, with heat stress of 35°C day/24°C night imposed for seven days at the milk or dough stages of grain filling. Elevated CO2 levels enhanced plant height, tiller number, spike length, and grain per spike, but led to reduced effective spikelets and smaller grain size. Heat stress during grain filling stages generally led to smaller grain sizes, exacerbated under elevated CO2 due to increased stomatal conductance and transpiration, causing earlier senescence. Genotypes with higher heat tolerance exhibited resilience, suggesting potential traits for screening heat-tolerant wheat genotypes.