Can Plant Growth Regulators Solve Lodging Problems?

GMAC 300-2502013 was a big year for western Canadian cereal crops, and with big yield can come big problems with toppling over. Lodging risk is a complicated mixture of genetics, a nutrient imbalance, nutrient deficiency, improper seeding rate or a combination of these factors. Having all those things in check is key, but if you still cant keep your crop standing then a plant growth regulator may be something that could be of benefit when looking ahead to next year.

Plant growth regulators (PGRs) are quite common in Europe and other grain growing regions, and have been used to achieve big crop yields in high production cereal fields. The primary use of these products is to decrease stem height at elongation which in turns thickens stem diameter and increases stalk strength. Plants treated with PGRs may also have a more consistent height between main stem, and tillers and may exhibit less apical dominance (essentially meaning the main stem doesn’t get first crack at nutrients over tillers anymore). There also may be a link between more efficient nitrogen use and allowing that plant to put the nitrogen towards yields and seed size vs. vegetative growth.

There are a few different types of plant growth regulators used around the world, with two types being the key ones in Canada. The first is a gibberellin inhibitor. Gibberellins are plant hormones that are important for stem elongation in the plant. These products decrease the plant synthesis of gibberellins, keeping the stems shorter. The next types are ethylene-based PGRs. The product is broken down into ethylene or stimulates ethylene production within the plant, which can decrease the amount of stem elongation in plants. These products are usually used in wheat or barley, but there are also products out there that have PGR effects on broadleaf crops.

There are minimal options in Canada for plant growth regulation right now, especially from an economical point of view. Companies are now doing work on them to test which actives are going to be crop safe and achieve a similar yield bump or plant benefit in Canada as they do in other parts of the world. As growers continue to push the envelope on yield, I predict an increased demand for products like PGRs.


Shane Thomas

Shane Thomas is an agronomist with G-Mac’s AgTeam in West Central Saskatchewan. He grew up in Kindersley, Sask and went on to obtain his Diploma in Plant and Soil Science from Lethbridge College and a Degree in Agricultural Economics from the University of Lethbridge in 2012. Shane enjoys playing sports, hanging out with friends, keeping up with the economy and reading in his spare time. Find him on Twitter: @ShaneAgronomy and his blog at:


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Plant growth regulators have a place, no doubt about it but growers need to start with the basics first. GPS reference soil testing then to Variable Rate Technology to place the nutrient and seed where it is needed to optimize profitability in the field and to minimize lodging. Then growers could look to PGR to push production.

Brian Rossnagel

Please note that this is not the first time GRs have been tried in western Canada. There was a big and unsuccessful push on such back in the early 1990s. More importantly please note that in almost all cases where GRs are applied to cereals one of the most common effects is that maturity is significantly delayed and for most of western Canada in most years that creates a significant negative problem.

Brian Rossnagel
U of Sask


Alberta ag did quite a bit of work on irrigated wheat in the 80s as I recall. We were not pushing yields as high at that time but possibly more important was low prices which indicated poor economic results. Might be interesting to dig some of that work out now.


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