With a late break to the season on the horizon, graingrowers are encouraged to select fast-developing varieties to allow crops the best opportunity for timely flowering, according to SARDI researcher Kenton Porker.
Mid North High Rainfall Zone trials at Tarlee and Kingsford last year helped to determine a optimum flowering window for newer barley, wheat and durum varieties.
Dr Porker said establishing a flowering period to increase yield potential was "vital to get the most out of new varieties."
MNHRZ trial sites at Tarlee compared flowering times of newer and more established wheat and barley varieties.
"The optimum flowering period for Scepter was September 12-30 because we recognised that if the flowering time was too early, the frost risk was too high and if it flowered too late, heat and declining soil moisture would have an impact," he said.
Dr Porker said Scepter wheat needed to be sown from May 6-26 to achieve that flowering date consistently.
To achieve the same optimal flowering date for barley varieties, Dr Porker said the largest lever growers had was sowing date and variety selection.
At the Kingsford trial site, fast-developing spring barley varieties such as Compass, Rosalind and Spartacus had a similar optimal flowering date to trials at Tarlee, on September 7.
"To achieve that those varieties need to be sown on May 15," Dr Porker said.
"Planet and Banks are slightly slower developing, so to achieve a similar flowering date it can be sown a bit earlier on about May 5-10," he said.
Dr Porker said long days and accelerated temperature controlled spring wheat and barley flowering period substantially.
"The trials showed most barley and wheat varieties will not progress from the vegetative phase until flowering occurs and the days get long," he said.
"Varieties have different sensitivity to long days. Cutlass wheat was sensitive to long days so it took a longer day for it to progress to flowering - Scepter was mostly reliant on temperature.
"That means if it is sown too early and temperatures are warm there is nothing to slow it down from progressing to flowering."
SARDI researcher Melissa McCallum's SA Grain Industry Trust trial at Tarlee compared the flowering periods of wheat and durum wheat varieties.
Scepter wheat and Saintly durum were sown on April 17 and both flowered on August 13.
"A more conventional sowing date of May 22 showed varieties had a similar flowering period - if growers are sowing Saintly they can be confident that sowing at the same time as Scepter is the best time to reach optimum flowering," Dr Porker said.
Weather system nears completion
THE Mid North Mesonet automatic weather station network across the Mid North, northern Adelaide Plains and northern Yorke Peninsula will be launched by September.
Penwortham-based ag consultant Mick Faulkner helped to form the weather station system in an effort to eliminate off-target chemical spraying.
"Industry is under the pump with the impacts of off-target spraying and we are not going to get new plant protecting chemicals - we are going to lose more than we gain so the whole network is about ensuring broadacre farmers have access to the latest information," he said.
Throughout the coming weeks, seven new automatic weather stations will be erected near Crystal Brook, Ngapala and Auburn, adding to the 33 already installed.
Mr Faulkner said determining the wind speed at 10 metres high was a key component to the mesonet because of the small spraying droplet size that is required.
"Measurements from the past three months showed that the wind speed at 10m is between five kilometres an hour and 20km/hr greater than the wind speed at 2m - that is a significant difference," he said.
"So we have been flying blind as to when we might have an inversion."
Experimental sites at Hart, Balaklava, Wandearah East and Korunye will also use three-dimensional wind sonics instead of two-dimensional to determine wind turbulence.
