Australia
February 20, 2015
WA’s first preliminary frost susceptibility ratings for commercially grown wheat and barley varieties will be available before seeding this year on the National Variety Trials (NVT) website at
www.nvtonline.com.au
These ratings have been generated on the back of three years of extensive field trials quantifying the effects of frost on 72 lines of wheat and 48 barley varieties.
This research is being conducted through the collaborative Australian National Frost Program (ANFP), which is one project of the GRDC’s multi-pronged National Frost Initiative.
The susceptibility ratings can be used to fine-tune frost mitigation tactics based on current management of known varieties with a similar rating.
Also now available on the NVT website is 2014 data from WA’s individual NVT sites and the long term multi-environment trial (MET) analysis.
NVT operations manager Neale Sutton says new disease resistance ratings for wheat and barley should be live on the NVT website by late February (depending on the disease).
Developing the new frost susceptibility ratings
The national frost susceptibility ratings project stemmed from previous GRDC investments that led to the development of frost screening nurseries in WA, SA and NSW.
These are able to measure susceptibility to reproductive frost under minor frosts with greater accuracy and repeatability.
In 2012, 2013 and 2014, trial sites were set up in Merredin and Wickepin in WA, Loxton in South Australia and Narrabri in New South Wales. Similar trials carried out in Loxton in 2010 and 2011 were also included in the analysis to improve predictions.
At each site there were between six and eleven times of sowing used - from about April 15 to June 15 - to increase the probability that the test lines were at the flowering stage when a natural frost event occurred.
On-site weather stations monitored the temperature at the crop canopy. After a frost event, 30 flowering heads were manually tagged and then assessed for frost induced sterility (FIS) of the outside grains during grain fill four to six weeks later.
FIS refers to intermittent or partial floret sterility and is often the combined effect of cold and freezing damage to the floral organs - primarily the anthers before and at flowering (at stage Z45-65).
This approach minimises confounding effects due to variety maturity and enables repeatable results to be generated across successive seasons and sites.
The trials included: a selection of the most commonly grown wheat varieties in the three states; varieties that had been well characterised previously for frost tolerance; and other entries of particular interest to breeding companies.
Summary of key trial results in WA
Led by Department of Agriculture and Food (DAFWA) frost researcher and head of the ANFP’s WA node, Dr Ben Biddulph (pictured), major findings for wheat varieties in WA’s 2012-14 trials included:
- Wheat varieties ranged in susceptibility to reproductive frost damage during booting and flowering
- No wheat varieties were frost tolerant
- Under severe frost (for example -4.5°C), or multiple minor frosts (several nights of -2º to -4ºC), all varieties tested were equally susceptible - resulting in up to 100 per cent sterility in flowering heads
- Variation in reproductive frost susceptibility was not linked to variation in susceptibility to stem frosts (as experienced in 2014 across southern Australia), or to later frosts during grain filling
Discussion and further details
Dr Biddulph will present recent frost developments by the ANFP at the 2015 Agribusiness Crop Updates, hosted by GRDC and DAFWA at Crown Perth on February 24-25. For more details and to register go to: www.giwa.org.au/2015-crop-updates
More localised information about frost and other research will also be provided at WA’s Regional Crop Updates, see www.grdc.com.au/Research-and-Development/GRDC-Update-Dates and agric.wa.gov.au/regional-crop-updates-2015
Dr Biddulph says the three-year trials showed that when wheat varieties were flowering on the same day and a frost occurred, there was a wide range in reproductive frost susceptibility (measured by FIS) in commercial wheat varieties under mild reproductive frost conditions (minimum temperatures of -1º to -3ºC). This is illustrated in Figure 1.
Under very severe frost (for example -4.5°C), or multiple minor frosts (several nights of -2º to -4ºC), all varieties trialled were equally susceptible, resulting in 100 per cent FIS.
Figure 1. Range in frost induced sterility for 12 frosts events from SA and WA trials in 2012-2013 when the same set of varieties were all tagged at flowering.
How to use new frost susceptibility ratings
Dr Biddulph will explain how the new frost ratings should be used during the Agribusiness Crop Updates.
A wheat variety will be given a preliminary rating as very susceptible (VS) or moderately susceptible (MS) to reproductive frost damage.
The ratings are not due to differences in phenology/flowering time, but refer to the relative susceptibility of varieties flowering at the same time.
Ratings do not take into account the frost risk associated with a particular variety’s flowering time given a certain sowing date.
Dr Biddulph says selecting an appropriate maturity for a particular sowing time is still the best option for limiting frost damage.
He says the new reproductive frost ratings should be considered in relation to the relative time of sowing and flowering time prediction - and frost/heat risk.
Tools to help determine this include DAFWA’s Flower Power: www.agric.wa.gov.au/frost/flower-power and Yield Prophet®: www.yieldprophet.com.au
It is recommended growers continue to select varieties based on the best yield, maturity, agronomic and disease performance information from sources such as regional agronomy trials and NVT.
Dr Biddulph says the preliminary reproductive frost susceptibility ratings can then be used to help fine-tune frost risk management tactics, based on current management of known varieties with a similar rating.
For example, Wyalkatchem
- which is very susceptible to frost - and Yitpi - which is less susceptible - are managed differently in terms of sowing date and position in the landscape and the associated frost risk to maximise production while minimising frost risk.
Ensuring that flowering occurs within the optimum flowering window to minimise frost, heat and terminal drought continues to be critical and the reproductive frost ratings need to be used in this context.
Note that, to date, variety differences in susceptibility to frost damage during stem elongation and grain filling have not been confirmed or linked to variations in reproductive frost susceptibility.
The reproductive frost ratings are preliminary and based on the variation in wheat varieties to maintain grain number under minor reproductive frosts at flowering time.
Further research is continuing in WA and nationally to validate the relationship between compensation ability, reproductive frost damage and grain yield.
This project is part of the GRDC’s National Frost Initiative which will provide genetic, management and environmental solutions to frost.
ENDS
Please note, this information can be reproduced in newsletters.
More information
Ben Biddulph, DAFWA
08 9368 3431
ben.biddulph@agric.wa.gov.au
Contact
Melissa Williams, Cox Inall Communications
042 888 4414
melissaw@coxinall.com.au
Useful resources
Ground Cover TV, Frost Ratings project, Episode #15, January 2015: www.grdc.com.au/GCTV15-FrostRatings
GRDC research behind the development of the frost rankings: www.grdc.com.au/MR-RDEOffensiveAgainstFrost
GRDC Hot Topic Pre-seeding Planning to Manage Frost Risk in WA: www.grdc.com.au/HT-PreseedingForFrostManagement
Ground Cover Frost Supplement: www.grdc.com.au/GCS109
National Variety Trial website: www.nvtonline.com.au
DAFWA’s Flower Power: www.agric.wa.gov.au/frost/flower-power
GRDC’s Yield Prophet®: www.yieldprophet.com.au
Photo: Bob Belford, GRDC National Frost Initiative.
Disclaimer: Any recommendations, suggestions or opinions contained in this publication do not necessarily represent the policy or views of the Grains Research and Development Corporation. No person should act on the basis of the contents of this publication without first obtaining specific, independent, professional advice. The Corporation and contributors to this publication may identify products by proprietary or trade names to help readers identify particular types of products.We do not endorse or recommend the products of any manufacturer referred to. Other products may perform as well as or better than those specifically referred to. The GRDC will not be liable for any loss, damage, cost or expense incurred or arising by reason of any person using or relying on the information in this publication.
CAUTION: RESEARCH ON UNREGISTERED PESTICIDE USE
Any research with unregistered pesticides or of unregistered products reported in this document does not constitute a recommendation for that particular use by the authors or the authors’ organisations. All pesticide applications must accord with the currently registered label for that particular pesticide, crop, pest and region.
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