Innovative research into how wheat phenology can be manipulated requires equally innovative methods to extend the information to growers.

Former South Australian Research and Development Institute (SARDI) researcher Dr Kenton Porker has been doing just that, engaging with growers and identifying crucial knowledge gaps using a smartphone-based real-time survey app.

Supported by the strategic research partnership between GRDC and SARDI, Dr Porker explored using agronomic interventions to alter the flowering time of early sown spring wheat and to optimise yield.

The project had an additional focus on extension, which included partnering with  AgCommunicators and Ag Innovation & Research Eyre Peninsula (AIR EP).

Managing climate risk

Dr Porker says the main purpose of the research was to help mitigate climate risk by identifying new strategies to reduce the yield losses caused by seasonal drought, frost and heat stresses.

“Our research focused on trialling novel agronomic levers to slow down or speed up crop plant development during the season, to give growers more options in-season,” he says.

The research has led to the development of a ‘reset’ strategy for wheat that offers the opportunity to plant a quick-developing variety early, irrespective of seasonal break timing.

“Following early rains, the 2020 season was notable for the number of growers who planted early and then contacted me for advice on slowing down crops they felt were developing too fast,”

“It showed me growers were keen to adopt new strategies that would help them realise the benefits of early sowing, and often dry sowing, while mitigating risk once the season was underway.”

Given the high level of interest among researchers, advisers and growers, a number of small demonstration trials were established in 2020 to build on experimental data from 2019. These included sites at Cummins and Giles Corner in South Australia and in the Victorian Mallee through Frontier Farming Systems.

Trial plots of early sown spring wheat and barley had their emerging apex deliberately pruned or ‘reset’ using either mechanical or chemical defoliation during the growing season. Mechanical defoliation (mowing) was found to be a simpler and more-effective mechanism.

The results showed a timely intervention could delay flowering by between nine and 18 days.

While flowering was successfully delayed at every trial location, the effect on yields varied. Across all sites in 2019, the reset strategy yielded an average 0.4 tonnes per hectare better than the mean yield for the slow-developing winter cultivar and was not significantly different to a quick-mid spring wheat sown on time (May) (Figure 1).

The yields for winter cultivars sown early were not significantly different to quick-mid spring wheat sown on time, but they were 0.6t/ha less than the quick-mid cultivar when both were sown on time and 0.8t/ha less when both were sown late.

Building the knowledge bank

A second objective for the project was to improve capacity for crop management, grower engagement and agronomic research in SA.

Dr Porker worked with AgCommunicators to deliver innovative extension sessions for growers at five sites across the Eyre Peninsula, Mid North and Mallee.

For the first time, these interactive workshops were enhanced by the use of Mentimeter, a commercial smartphone app that allows participants to engage with the presentation and answer survey questions in real time.

AgCommunicators director Belinda Cay says being able to survey growers while they were attending Dr Porker’s presentations provided detailed insights into their agronomic practices, preferences and knowledge gaps.

“While there were issues with mobile coverage at some sites, we captured enough good data to compare the different locations and aggregate the overall results,” she says. “Grower feedback was positive and we felt the interactivity improved their level of engagement.”

Growers at each workshop were asked a range of questions to assess their attitudes to early sowing times and early sowing risks, sowing time decision drivers and optimal flowering periods.

The data showed growers had a good understanding of the importance of flowering time and the risks in each location. However, the results also revealed some interesting anomalies.

“We could see that Eyre Peninsula growers believed their optimal flowering time was about a week earlier than the modelled data would suggest, while Mallee growers estimated their optimal flowering period to be a week later than the models,” Dr Porker says.

“We were able to drill down into their responses and determine that Eyre Peninsula growers were understandably more concerned about the onset of heat stress, while Mallee growers were more concerned about frost.”

Questions about barley sowing times revealed lower Eyre Peninsula growers preferred to plant barley later than wheat, while Mallee growers preferred planting barley before wheat. However, Mallee growers do not necessarily have access to cultivars suitable for earlier sowing in their region.

The feedback highlighted a need for a greater diversity of barley cultivars to suit different regions.

Dr Porker and AgCommunicators are now working to deliver additional extension materials, while the GRDC National Phenology Initiative has been established to better predict optimal flowering times for wheat and barley varieties across Australia’s major cropping regions.

The initiative will deliver data that growers and advisers can use to make cultivar and time of sowing decisions for their specific environments. This will be available by the middle of 2022.

Meanwhile, Dr Porker says research manipulating plant development in-season has the potential to increase yields by optimising flowering times and decreasing losses to frost.

“Growers generally base their key agronomic decisions around time of sowing, but in-crop management enables a more flexible response to the unfolding season,” he says.

“Based on our modelling, the reset technique has potential to provide growers with a relatively low-cost adaptation tool in a warming and drying climate.

“The reset technique is more readily adoptable than winter wheats because growers do not need to buy and store seed for a back-up cultivar, with no clear timeframe for its use.

“The method is also applicable to barley, which does not have the same late emergence downside as winter wheat, allowing it to be grown in a wider range of agro-ecological zones.”

View a video report from Mallee Sustainable Farming.

More information: Dr Kenton Porker, kenton.porker@faraustralia.com.au