Alberta Barley

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Effect of plant growth regulator application on yield and quality of malting barley

Project lead:
Dr. John O’Donovan
Research Scientist
Agriculture and Agri-Food Canada

Timeline: April 2013 – March 2018



Alberta Barley funding: $38,631
Total funding from other partners: $275,343

Benefits for barley farmers
Assuming no significant negative effects, PGR application could reduce lodging, increase yield and possibly increase the amount of barley acceptable for malting. Growers would then have an important tool to reduce lodging and increase yield.

Plant growth regulators (PGR) can be a very cost-effective method of reducing the incidence of lodging, which can cause barley yield losses of up to 80 per cent. However, little research has been conducted in Western Canada on their effects on malting barley. This project will assess the risks and/or benefits associated with applying PGRs to mitigate lodging and associated quality and yield loss of malting barley.

Developments – June 2016
The results from this year and previous years indicate that the effects of applying PGRs to malting barley can be very variable. Ethephon application often reduced plant height and lodging, and sometimes increased yield. However, yield decreases also occurred on occasion. In addition increased tillering with ethephon was problematic and could lead to uneven maturity and non-uniform kernels. Interestingly, the reduction in kernel size caused by ethephon application resulted in better endosperm modification without compromising malt extract. In 2015, trinexapac was more likely to increase yield than chlormequat, and neither PGR compromised malting quality. However, the variability on yield and other factors documented in this study suggests that PGR application for malting barley production may be limited.

This objective of the project was to study the effects on the agronomic and grain quality after applying PGR’s chlormequat, trinexapac and ethephon on malting barley in order to mitigate lodging. This project identified benefits and risks to using plant growth regulators in western Canadian through the trial being conducted at 5 locations over 3 years (15 site-years). This project will benefit producers by determining whether or not PGR applications were useful in malting barley.  If they were not useful they could save barley farmers money.  If they were useful it provides a new tool for producers.

The field portion of the project was completed in 2016.  Data have been analyzed, and summarized and presented at extension events.  A scientific manuscript has been submitted for publication to Canadian Journal of Plant Science.

Results indicate that overall the ability of the PGRs to mitigate lodging were limited although they were quite successful in reducing height. Trinexapac and ethephon were most successful at reducing height. However, they also had negative effects on agronomic and pre-malt quality measurements like days to maturity and percent plumpness. Chlormequat did not reduce lodging when averaged across sites.  Trinexapac increased yield across site-years but was inconsistent among individual site-years. Ethephon increased the number of tillers per plant, while ethephon and trinexapac increased days to maturity, and reduced kernel weight and percent plump kernels.

Unfortunately, while positive effects of plant growth regulator applications were observed, they were limited and inconsistent.  The observed negative effects on days to maturity and pre-malt quality were more consistent across and within site-years. This indicates the plant growth regulator applications tested may have limited benefit and may actually increase quality risks in western Canada, and would not be recommended for western Canadian malt barley producers based on this study.

Updated July 16, 2018