In theory, the application of a plant growth regulator to wheat should result in shorter, stronger plants that are less prone to lodging, enabling higher yield potential. In reality, it’s not that simple.
“I wish it was a nice black and white, straightforward story, but it certainly isn’t,” says Sheri Strydhorst, who’s done extensive work with PGRs in wheat in her role as research scientist with Alberta Agriculture & Forestry.
“What we’re seeing on wheat is that different cultivars respond differently. For some cultivars it works (according to the) textbook, just beautiful,” she explains in this Wheat School episode. “However there are cultivars where they sometimes get taller under some conditions. Sometimes it fixes lodging but not enough to straight-cut it. There is no real straightforward answer.”
Yes. You read that right. PGRs sometimes make plants taller. Because they break down quickly in the plant, you can get a flush of hormones telling the plant to elongate, she explains.
“Plant hormones are complex systems. When you do something at one point it can have ripple effects downstream,” says Strydhorst. (continues below)
There are currently two registered PGR chemistries for wheat in Canada; they’re marketed as Ethrel from Bayer and Manipulator from Engage Agro. Strydhorst’s research is also contributing to the registration package for a third formulation.
She says there’s a complex interaction between variety, chemistry and conditions. For example, there have been consistent height reductions and standability improvements with AC Harvest, while other varieties show height reductions but no improvement in standability. CDC Go has grown taller in some cases, she says.
“Ideally it would be nice to have a little guidebook that says yes, use it on cultivar XYZ and not on ABC, but we’re not there yet,” says Strydhorst.
So what’s her recommendation? Should growers apply a PGR?
“If you’re planning to do it, do your homework, particularly on the marketing,” she says, referring to the United States’ zero tolerance for wheat treated with Manipulator (this doesn’t look to be changing for ’16). “Make sure you’re in a growing area that does have lodging, where you need it. Make sure you get staging right and do your homework to make sure it’s a cultivar that responds nicely to it. Don’t go in blindly.”