High yields of malting barley start with the correct seeding rate
Sowing the correct number of seeds/m2 is vital in order to achieve top yields in spring malting barley, Rebecca Bayley, Teagasc/Boortmalt Joint Programme advisor, told delegates at the recent National Malting Barley Conference.
“We aim for 350 seeds/m2. With an approximate establishment rate of 85%, that would give you 300 plants/m2. Provided that it’s a typical malting barley growing season, having these 300 plants/m2 will ensure good tillering.
“The crop will produce our target of achieving 1,000 head/m2 come harvest time. Without these 1,000 heads/m2, it would be hard to maximise yields, therefore it essential to have the correct seeding rate,” she explained.
For growers sowing malting barley in the coming days and weeks, Rebecca advised them to pay particular attention to the thousand grain weight (TGW) and to adjust sowing rates accordingly.
“In order to ensure the correct number of seeds are placed into the seedbed, it is important to use the thousand grain weight (TGW) of each variety,” she outlined, “it’s vital to check the TGW of the seed you have purchased as this can vary between lots of seed that’s certified, as TGW is analysed per lot, so growers should check this or ask their suppliers.”
Once a grower has the TGW for the variety of seed they are planning to set, Rebecca advised them to use the following formula to establish the seeding rate required - average TGW multiplied by target plant population per m2 divided by the establishment rate.
Outlining some previous on-farm demos carried out by Eoin Lyons on the Teagasc/Boortmalt Joint Programme, which examined the effect of seeding rate on malting barley performance, when one seeding rate was dropped by 20% below standard seeding rates to mimic poor establishment, Rebecca commented that both Planet and Laureate produced 1,000 ears/m2 when standard seeding rates were used in 2021 and 2022, but both varieties failed to reach 1,000 ears/m2 in 2021 and 2022 at the reduced seeding rate.
“In a typical malting barley growing season, having 300 plants/m2 will ensure good tillering of the crop and produce enough heads when it comes to harvest time, which is critical in order to get a high yielding crop,” she noted.
Figure 1: Results of the Teagasc/Boortmalt Joint Programme seeding rate demo
Rebecca also commented on a follow up demo, looking at the application of a plant growth regulator (PGR) to the recommended seeding rate, the reduced seeding rate of 20% and a control, to examine the role it plays in promoting tillering rather than preventing lodging. The number of tillers and ears recorded post application was compared to the control for 2021 and 2022. Again both Planet and Laureate were the varieties grown.
Summarising the results of this on-farm demo, involving the Teagasc/Boortmalt demonstration farms, Rebecca noted: “By having the correct seeding rate there is no advantage to applying the PGR. For growth regulators to work efficiently they are very much reliant on having the correct growth stage and are very much weather dependent also.”
“From a malting barley point of view, if a grower has the correct number of plants to start with and the correct number of tillers, applying a PGR may produce more tillers but they may not make it to harvest, resulting in green immature grain that could have the potential to increase protein,” she commented.
“As a grower, at a lower seeding rate, you are much more dependent on everything to go right in the growing season to be able to get your maximum yields and your 1,000 heads/m2 when it comes to harvest. PGRs may help, but ensuring the correct seeding rate is essential and a lot more predictable,” she concluded.
Also read: Tillage advice: Guidance on spring cereal planting