27 February 2024
PGRs and tillering in malting barley
A trial conducted as part of the Teagasc/Boortmalt Joint Programme looked at the effectiveness of plant growth regulator (PGR) to promote tiller production in spring malting barley crops when sown at optimum and sub-optimum seeding rates.
Joint Programme Advisor, Rebecca Bayley presented the key findings of this trial work at the recent Malting Barley Conference, where she highlighted the limited role PGRs play in terms of tillering when the optimum number of malting barley plants are established.
Carried out on the five demonstration farms enrolled in the programme, the trial examined the effectiveness of PGRs to promote tillering on standard seeding rates (optimum to achieve a plant count of 300 plants/m2) and a reduced seeding rate – to mimic a poorly-established crop – where the seeding rate was reduced by 20%. This trial was a follow on from a previous demonstration on the monitor farms which had shown that in a typical malting barley year having 300 plants/m2 will ensure good tillering and the production of 1,000heads/m2 at harvest time.
Rebecca explained: “The PGR was applied to examine the role it plays in tiller production, rather than preventing lodging. PGR was applied at optimum rates at mid-tillering and the number of tillers would have been recorded post application and compared to the control, where no PGR would have been applied.
“Throughout the growing season, data would have been collected on the monitor farms and by combining all this information – from plant counts to head counts – an insight was gained as to the performance.”
Presenting data from 2022 and 2023 on the variety Planet, Rebecca said: “Where there was a reduced seeding rate, the application of PGR did have its benefits, but these tillers might not necessarily be brought to harvest. When you have your recommended seeding rate, there is no advantage to adding a plant growth regulator.”
On the above mentioned benefits of applying a PGR to the reduced seeding rate, Rebecca highlighted that it resulted in just a 4% increase in heads/m2 come harvest time, adding: “Both 2022 and 2023 were two very different growing seasons, but regardless – where you have the correct seeding rate – there’s no advantage of adding plant growth regulator. Where you have the recommended seeding rate, the application of plant growth regulator has no effect on tillers produced or heads produced.
She added: “Barley needs the seed in the ground to produce plants that produce heads. By having the correct seeding rate, there is no advantage of applying a plant growth regulator. This message has remained consistent, even with the unusual weather conditions experienced over every year this trail has been implemented.”
Also read: Giving this year’s malting barley crop the best start