Research identifies canola sowing window

Research identifies canola sowing window


Grains
DPIRD research officer Martin Harries and DPIRD research officer Imma Farre spoke together on the topic of optimum sowing windows for canola in Perth last week.

DPIRD research officer Martin Harries and DPIRD research officer Imma Farre spoke together on the topic of optimum sowing windows for canola in Perth last week.

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While there had been interest in dry sowing very early canola, field trials found that moving the sowing window forward to March and early April was a risky option in the northern region.

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CANOLA growers in the northern and central agricultural regions are set to benefit from the outcomes of sowing time and variety selection research, which have revealed more flexible options for growers.

Department of Primary Industries and Regional Development (DPIRD) research officer Martin Harries, who spoke at last week’s Grains Research and Development Corporation (GRDC) Grains Research Update in Perth, said the research, with GRDC co-investment, identified a number of varieties with good yield stability across a range of sowing dates, which would help reduce the risk of dry sowing and the need to purchase multiple maturity types. 

Mr Harries said while there had been interest in dry sowing very early canola, field trials found that moving the sowing window forward to March and early April was a risky option in the northern region.

“Establishing canola in early autumn proved to be difficult in this region, due to the impact of hot, drying soil conditions and the need to sow canola shallow, due to its small seed size,” Mr Harries said.

“It shows that the soil temperature needs to be around 30 degrees Celcius or lower to get crop establishment which didn’t occur until around late March.”

Mr Harries said the research also showed sowing canola varieties with a wide flowering window at dates later than normal generated more encouraging results, however, there were large differences between the 11 varieties trialled.

“The responses from the triazine tolerant (TT) hybrid varieties were well above what would be expected from later sowing dates, with plots sown on May 17 at Tenindewa, west of Mullewa, yielding 1.6 tonnes per hectare overall,” he said.

“The highest yielding varieties at Tenindewa produced around 0.8t/ha when sown very late on June 20. 

“These new short season hybrids flowered early and put on substantial bulk and were flexible enough to keep flowering while the season was favourable, which gave the yield response. 

“The introduction of these plant types may provide growers with an option to reduce the risk of late sowing or late emergence from dry sowing in this environment.

“In the central region trials at Wongan Hills and West Dale, south of Beverley, mid-season varieties had the most flexibility in their plant development and flowering duration.”

Mr Harries said the analysis at these sites suggested mid-season varieties could provide a flexible option for growers, providing the opportunity to pre-order seed suitable for a reasonably wide sowing window. 

“This is becoming more important, as more canola is being dry sown and the establishment date at the break of the season can be unpredictable,” he said.

The research outcomes were reinforced by Agricultural Production Systems sIMulator (APSIM) modelling, which simulates flowering dates and yields across locations and sowing dates.

DPIRD research officer Imma Farre said the modelled flowering dates compared reasonably well to the observed data from the mid-May sowing trials. 

“The APSIM-Canola model was used to obtain the optimum sowing window where maximum canola yields would be achieved on average for different season length varieties and locations, keeping in mind the actual season is rarely similar to the average year,” Dr Farre said. 

“While the APSIM-canola model has been validated for WA for the traditional sowing window and for older varieties, further model validation is required to extend the use of the model to very early sowings and new varieties.

“What we have found is that wetter areas have a longer response time when it comes to the optimum sowing window.”

Optimum sowing times as generated by APSIM included Geraldton April 14 to May 14, Wongan Hills April 8 to May 6, Lake Grace April 4 to April 27, Kojonup March 3 to May 8, Mount Barker April 8 to May 30 and Salmon Gums March 26 to April 25. 

Wetter and cooler areas such as Mount Barker, which has a 52-day sowing window, have larger windows compared to Lake Grace which has a sowing window of 23 days according to APSIM. 

Mr Harries said the research would be replicated and extended in 2019 to include field trials at Esperance, to determine whether the findings could be extended to the southern region.

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