Australia
April 1=20, 2018

Northern wheat growers who target an optimum flowering date and match their variety selection accordingly are in the box seat to minimise yield penalties from frost and heat events.

It’s a premise that Queensland Department of Agriculture and Fisheries (DAF) senior regional research agronomist Darren Aisthorpe (pictured) knows only too well having been involved in a comprehensive research project investigating phenology and yield responses to sowing date for a range of wheat genotypes.

The research spans eight trial sites stretching from Wagga Wagga to Emerald and is a collaborative research investment between the Grains Research and Development Corporation (GRDC) and NSW Department of Primary Industries (DPI), with assistance from DAF QLD.

These trials build on extensive previous research work undertaken through the Variety Specific Agronomy Packages project to assess the interaction between different agronomic management practices (such as time of sowing, plant population and nutrition) and flowering dates, grain yield and quality.

The geographic diversity of the current sites was chosen to give researchers critical data about how different varieties perform in different regions with a focus on time of sowing, flowering and yield responses, which in turn can help guide growers on variety selection and sowing management.

Speaking at the recent GRDC Grains Research Update at Goondiwindi, Mr Aisthorpe said the research had highlighted the importance of understanding temperature variance across individual farms and regions as a means of targeting optimum flowering windows for wheat.

“The research has shown that days to flowering for a variety can vary significantly between locations and between planting dates, so observing and recording on-farm flowering dates from year to year could become a very useful management tool when trying to select the most appropriate variety,” Mr Aisthorpe said.

“Targeting an optimum flowering date is key to maximising grain yield by balancing heat and frost risks.

“At the same time, selecting varieties with known and understood flowering dates allows more informed variety/maturity selections for future crops.”

Genotypes vary in their response to vernalisation and photoperiod which influences early development phases as well as flowering time.

Genotypes responsive to vernalisation require a period of cold temperatures (accumulated most rapidly in the range 3°C to 10°C) to progress from vegetative to reproductive development, whilst time to flowering is accelerated during long-days in photoperiod sensitive genotypes.

According to Mr Aisthorpe, the CliMate application (climateapp.net.au) is a valuable tool for assessing the probability of a heat or cold stress event occurring based on historical weather data for a given location. This can assist growers to identify a time of sowing that targets a safer flowering period.

Mr Aisthorpe said it was important to remember that no individual wheat variety would maximise yield across the full planting window and that the yield response for particular maturities/varieties would vary depending on time of sowing.

He said the general trend across all research locations showed consistently declining yield from the first time of sowing to the last.

“Excluding an exceptionally early (March) plant, generally the earlier the crop is planted within an accepted planting window, the higher the yield potential (baring frost damage),” he said.

“As 2017 showed us, frost is a significant consideration, however so too is heat stress. The advice is to not take too conservative an approach to frost mitigation, as chances are it will cost you significantly in yield largely as a result of heat stress.

“Those considering planting very late in the traditional planting window run a high risk of flowering in heat stress conditions and may actually be better off waiting a month or so and chasing a potentially more lucrative early summer crop instead.”

A copy of Mr Aisthorpe’s GRDC Grains Research Update paper can be downloaded from the `Resources and Publications’ section of the GRDC website www.grdc.com.au

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

Published: April 20, 2018