Flowering time the bottom line for canola profitability

Canola flowering time crucial for yield potential

Cropping
Optimising canola's flowering time is currently one of the most important tactics in improving profitability of the crop.

Optimising canola's flowering time is currently one of the most important tactics in improving profitability of the crop.

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App developed to calculate canola's flowering time.

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NSW DPI researcher, Rohan Brill, says optimising canola's flowering time is currently one of the most important tactics in improving profitability of the crop.

"In the last couple of years we've been penalised by frost by flowering too early but then quickly we drop our yield off by flowering late because of drought and heat-stress, so it's become a tight window to get the highest yield," Mr Brill said.

"Last year we were dropping off nearly 15 kilograms per day per hectare by flowering too early and a similar sort of rate by flowering too late as well."

Mr Brill was one of the 16 researchers working on a five-year GRDC project on optimising canola profitability, the group presenting their findings to growers at workshops across Southern NSW.

An app from CSIRO, The Canola Flowering Calculator, was developed as part of project.

The app allows growers to determine the best variety or sowing date, depending on their location, so their crop flowers in the optimal window.

The calculator is a phenology model that uses 60 years of weather data to calculate a range of possible flowering dates for a specific environment.

The Canola Flowering Calculator gives growers insights on what variety to sow or what date to sow so canola flowers at the optimal time.

The Canola Flowering Calculator gives growers insights on what variety to sow or what date to sow so canola flowers at the optimal time.

Mr Brill said the information was particularly useful because you can pick from 77 sites around Australia.

"If you're a farmer at Lockhart and you're unsure about what your variety is going to do, you can get online, put your location in there and then have confidence that the weather data will be based on where you are," Mr Brill said.

"That will really help, especially when we get new varieties in there."

A key component of the project was trialing a range of canola varieties, at different locations and across different sowing dates.

Mr Brill said when it comes to hybrid or OP varieties, hybrids came out as the overall winner but it had a higher risk factor.

"Hybrid's are more expensive, so in a high risk situation there's probably good reason to go back to OP variety," Mr Brill said.

He said they've seen more consistent yields across sowing dates and seasons from varieties that sit in the middle in terms of speed of development.

"The slow varieties do quite well if they're sown early but then struggle if they're done late," Mr Brill said.

"If we miss the sowing opportunity like what happened in 2018 then if that's the only variety you've got, you're either in a system where you know you're getting a lower yield or not sowing at all.

"Fast varieties have to be sown late or they'll be frosted, whereas the varieties in between have a little more flexibility to flower at close to the right time over a wider window."

He said there were some new varieties like Diamond that stood out.

"Diamond was quite phenomenal in that it put a lot of biomass on quickly but it's very risky pushing it early because it flowers very rapidly and then gets exposed to frost," Mr Brill said.

He also said the way nitrogen was applied had changed over the last couple of years as farmers have looked to reduce their inputs.

"We got fairly gungho in terms of just feeding the system with urea because we had some pretty handy years from 2010 to 2016," Mr Brill said.

"We've turned around those last couple of years and cropping in general has been more risky.

"Growing canola after a legume has taken a lot of risk out of that because it hasn't needed as much fertiliser."

Flowering time affects disease resistance

Researchers have found both sowing and flowering time can have a significant affect on a canola crop's resistance to diseases such as blackleg.

CSIRO's Dr Susie Sprague said although sowing earlier reduced the risk of blackleg, flowering early could increase risk.

"If you're sowing earlier you're sowing into warmer soil so the crop's growing quickly and they usually reach a stage where they're more robust to the disease before the fungal spores are released," Dr Sprague said.

Upper Canopy Blackleg affects canola crops at the late-end of the season. Photo supplied.

Upper Canopy Blackleg affects canola crops at the late-end of the season. Photo supplied.

"However, the earlier that the crop flowers the more exposed they are to blackleg spores and cooler conditions that are conducive to the disease development."

Dr Sprague said it was also important for growers to understand that there was a new type of blackleg infection affecting plants in the later end of the season, named upper canopy blackleg.

"It's affecting the crop once it has its reproductive canopy. The term encompasses infection on a number of plant parts," Dr Sprague said.

She said although the dry season meant significant levels of disease were unlikely this year, higher rainfall areas could experience yield loss.

"In previous seasons we have certainly measured significant yield loss associated with upper canopy infection and it is advisable that growers become familiar with the symptoms," she said.

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