Australia
September 17, 2015

By GRDC western regional panel member Darrin Lee (pictured)

Western Australian research has shown that canola is most vulnerable to heat damage at flowering and early pod fill stages, and that high temperatures can halve the yield potential of some varieties.

Unseasonably hot weather has reduced the yield potential of many WA canola crops in recent seasons, and some cropping areas this year experienced record temperatures exceeding 34°C in early September.

The Grains Research and Development Corporation (GRDC) is supporting a major canola heat tolerance research project at The University of Western Australia (UWA) which aims to identify heat tolerant genes and breeding material for canola breeders.

It is also establishing protocols that breeders can use to screen breeding lines.

The UWA Institute of Agriculture and School of Plant Biology researcher Sheng Chen inspects the flowering and podding status of early-sown canola plants in trials at UWA.

This research is part of the National Brassica Germplasm Improvement Program which aims to provide canola breeders with advanced genetic lines so Australian growers have access to cultivars that allow them to compete effectively on world markets.

Researchers led by UWA’s Institute of Agriculture and School of Plant Biology researcher Sheng Chen have confirmed that the most heat-sensitive stage for canola is seven days before and after the plant produces its first open flower.

According to Dr Chen, a range of canola varieties at this stage of development suffered average yield reductions of 20 per cent when subjected to temperatures of 35°C in a controlled environment.

The most heat susceptible varieties suffered yield losses of up to 50 per cent when exposed to these temperatures in field trials.

Dr Chen says the information could be used by growers to help them adjust sowing times and select varieties to minimise the risk of yield losses.

By checking historic temperature records and variety information, growers can adjust sowing dates so that a canola variety is less likely to start flowering during higher temperatures.

Most canola crops are unlikely to start flowering when temperatures are as high as 35°C. However, late sown crops may be at risk of being exposed to damaging temperatures of above 30°C.

Dr Chen says it is also worth noting that hot weather has occurred earlier in the season in many WA cropping areas in recent years.

The new information will also be useful to canola breeders as they will only need to assess breeding lines for heat tolerance during the two-week period around the onset of flowering.

Another achievement by Dr Chen and his team is the selection of canola lines with potential heat tolerance, following two years of field trials and glasshouse studies.

These lines – sourced from around the world – will undergo further evaluation under controlled conditions at UWA and can be used as parental lines for heat tolerance improvement in canola breeding programs.

Website: http://www.grdc.com.au

Published: September 17, 2015