Sowing date is the most critical factor in maximising productivity and grain quality of barley.
That is the key finding to come out of the Southern Barley Agronomy project, a GRDC investment led by the NSW Department of Primary Industries (DPI) and conducted across NSW, Victoria and South Australia, which has recently wrapped up.
The research sought to uncover whether different varieties respond differently to different management.
South Australian Research and Development Institute (SARDI) research scientist Dr Kenton Porker says the response to sowing date comes back to crop development the biggest lever growers have in maximising yield and grain quality.
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Matching plant phenology to the environment and sowing on time is the first thing to get right before other management factors, such as sowing rate and nitrogen, he says.
Dr Porker defines three distinctive plant types among barley varieties.
The first is erect, fast-developing cultivars examples include Hindmarsh (PBR), La Trobe (PBR), Spartacus CL (PBR) and Rosalind (PBR).
Then there are taller, fast-developing cultivars with greater early vigour examples include Compass (PBR) and Fathom (PBR).
There are also mid to fast-developing cultivars examples include the European cultivar RGT Planet (PBR) and Banks (PBR).
Dr Porker says the key in understanding the management of each of these types is to look at how each achieves their yield.
If you take the erect varieties, their yield is derived from head number and, therefore, they rely strongly on tiller production and therefore they are more responsive to nitrogen in some situations, he says.
The early-vigour varieties such as Compass (PBR) achieve their yield advantage through larger grain size and are, therefore, suited to environments with lower rainfall and where there is risk of drought or heat stress.
While barley is slightly more frost tolerant than wheat, our 2017 trials showed a need for caution in sowing the fast-developing varieties pre-May in frost-prone areas.
Matching plant phenology to the environment and sowing on time is the first thing to get right before other management factors, such as sowing rate and nitrogen
As part of his PhD studies, which have also recently finished, Dr Porker looked to validate the key genetic components of Compass (PBR) under different sowing date environments.
In this, he looked to determine why Compass (PBR) was so much higher yielding than parent variety Commander (PBR) and achieving five per cent higher grain weight, even when flowering on the same day.
This all comes back to the fact Compass (PBR) has better partitioning than Commander (PBR), Dr Porker says.
Compass (PBR) manages to get its biomass back into the grain a little more efficiently than Commander (PBR).
"We tried to pull apart the genetic drivers of that five per cent difference, and it all came back to the major crop-development genes, with response to photoperiod being the main one.
Dr Porker says RGT Planet (PBR) achieves its yield advantage through more grains per spike, which is determined just prior to flowering time.
This means growers can plant a week or two earlier than the faster-developing cultivars to ensure the period of spike development coincides with more favourable conditions, this means growers may have to absorb some of that frost risk to ensure they are achieving those grain numbers per spike, he says.
RGT Planet (PBR) is best suited to medium to high-rainfall areas with a yield potential beyond four tonnes per hectare and is generally suited to early-May sowing.
Despite its European heritage, Dr Porker says RGT Planet (PBR) has a phenology type well-adapted to many Australian areas.
There is a common belief that because RGT Planet (PBR) is European, it flowers late," he says.
"However, if it is sown in the first week of May then it flowers before Commander (PBR) and should be considered.
It also has better drought tolerance than other European varieties we have seen in Australia.
"But, having said that, it is still not as well-adapted to drought and heat stress conditions as Australian-bred varieties when you consider grain size and test weight.
More information: Dr Kenton Porker, 0403 617 501, email@example.com
Useful resource: GRDC southern GrowNotes: grdc.com.au/GN-Barley-South