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Ontario Grain Farmer Magazine

Increasing lodging resistance in oats for enhanced quality and yield

Principal Investigator: Joshua Nasielski

Research Institution: University of Guelph

Timeline: April 2020 – March 2023  

Objectives:

  • The overall objective is to develop a suite of data-backed agronomic options for farmers who want to increase the lodging resistance of their oat crop.
  • To quantify the effects of five agronomic practices (seeding density, row width, seeding depth, split-N applications, Plant Growth Regulators PGR)) on lodging resistance in Ontario on a subset of lodging-prone and lodging-resistant oat varieties approved for milling oat use by Quaker/PepsiCo.

Impacts:

  • By developing data-backed agronomic options to increase oat lodging resistance and presenting them to farmers, the project will increase the profitability of oat production in Ontario by: a) reducing harvest difficulty, b) avoiding lodging-related yield loss, c) avoiding quality reductions that would prevent marketing as food-grade oats and d) enable more intensive oat management (e.g., higher nitrogen (N) fertilizer rates).
  • Globally, human demand for oat-based products is increasing and oat production/prices are expanding. As consumer interest in healthy foods and plant-based proteins increases, it can be expected that consumption of oats, which have the highest protein levels of any cereal, will continue to increase after decades of decline. Additional oat agronomic research is warranted in areas where milling oat marketing opportunities are greatest. This research will benefit the oat value chain within the province. Additionally, in areas of southern/eastern Ontario where winter wheat is frequently winterkilled, farmers who want to keep a cereal in their rotation need options for profitable spring cereal production.

Scientific Summary:

Lodging is a major constraint on profitable milling oat production in northern Ontario, as it reduces oat grain quality and increases the difficulty and time required for harvest. The risk of lodging also constrains the profitability of more intensive oat management, specifically increased nitrogen (N) fertilizer rates.

Lodging is the result of genotype by environment by crop management (GxExM) interactions. Lodging is most common in high-yielding years, meaning oat farmers cannot take full advantage of ‘bumper crops.’ Lodging is also variety-specific, being less common in short-stem (‘dwarfing’) oats. However shorter oat varieties still lodge, and in Ontario root lodging (as opposed to stem lodging) is most common. There is a need to investigate potential agronomic solutions to enhance oat rooting characteristics and minimize lodging. We proposed to test four potential agronomic practices which increase oat lodging resistance, on-farm and at research stations:

1. Reduced seeding density and/or row width in high-risk areas: As seeding density increases lodging risk increases. This is because increased intra-plant competition at higher seed densities reduces stem strength, root plate spread and root number. Reductions in seed density in lodging prone fields may be warranted. And at fixed seeding densities, adjusting row widths may be an additional way to modify inter and intra-row competition to reduce lodging susceptibility.

2. Increased seeding depth: Oat can tolerate deeper seeding depths than other cereals. Deeper seed placement may enhance lodging resistance, as has been shown in rapeseed, by increasing structural rooting depth.

3. Split-N applications: Reduced early season N availability can reduce lodging by enlarging stem wall width and root strength. A preliminary study at New Liskeard Agricultural Research station found that split-N applications (60 kg N ha-1 at planting and 30 kg N ha-1 at flag leaf) reduced oat lodging without impacting yield.

4. Plant Growth Regulators (PGR): Not commonly used in Ontario, but several new PGRs entered the Ontario market for the 2020 growing season and some showed promise on oats.

Results:

1) Narrower row spacing consistently increased yield across environments and genotypes but also increased lodging in some environments.

Narrower row spacing increased grain yield by an average of 0.8 Mg ha-1 over wider row spacing. The average grain yield in Ontario (2017-2022) is 5.4 Mg ha-1, suggesting that narrower row spacings could increase yields by an average of 14%.

Narrowing row spacings may require a significant investment in new equipment or equipment modifications. However, for farmers who plant substantial amounts of small-grain cereals, this may be worthwhile.

2) Seeding rate had variable impacts on yield and lodging but reduced seeding rates generally reduced lodging.

For a field (or areas of a field) prone to lodging, reducing seeding rates can also reduce lodging. However, the effect of reduced seeding rates on lodging was variety-specific and was correlated with reduced yields. On one hand, seeding costs will be lower, but yield may be lower as well. The evidence points to an effective reduction in lodging (overall) when lowering seeding rates to 50% of recommended seeding rate. The take-away is that this is a valid practice, but farmers should experiment to see if reduced seeding rates works with their preferred varieties.

3) Seeding depth had no effect on yield but shallow seeding increased lodging in one environment.

In Ontario, the recommended seeding depth for oats is 2.54 cm (OMAFRA 2017). In 2021, we found that when average oat seeding depth was 2.6-2.7 cm lodging was increased (New Liskeard) and root plate depth reduced (Winchester). Depending on the type of seeding equipment used, even when average depth achieved is 2.54 cm (1’’), a substantial number of seed will be sown shallower than this. As such, setting the seed drill to a deeper target depth than 2.54 cm is recommended as deeper seeding had no effect on yield or grain quality. This is a costless strategy that can reduce lodging due to shallow-sown seeds.

4) Plant Growth regulators reduced lodging in some environments, especially as N rates increased, and had no effect on yield.

The plant growth regulator tested (Moddus on-station) reduced crop height and lodging in 2 of 4 site-years. In the 2 years where there was no crop height response to Moddus, it is suspected that the product was applied too early and in conditions that were too warm to be effective.

PGR’s never increased yields or grain quality in the on-station trials, even though lodging always occurred. However, by reducing lodging, harvesting/combining is easier (less money spent on fuel, for example). In general, yield losses from lodging are likely to occur when lodging happens early in the season (e.g., early grain-fill), which did not occur in 2020 or 2021.