The Effects of Wildfire Smoke on Grass

Purpose

Grass crops, such as wheat, barley and oats, are important in Canada. Wildfires happen every year and increase in frequency and size. How does wildfire smoke affect the germination, growth and development of crops?

Background Information

Wildfires are common in Canada. 2023 set a new record of 18 million hectares burned (the size of Cambodia) (Canadian National Fire Database, 2026).

Wildfire smoke is widespread and is harmful to humans- but what about our food?

Our food is heavily dependent on grasses.

Cereal crops are a $68.9 billion dollar industry in Canada giving income to 370,000 Canadians and feeding millions. Cereal crops are grasses (Carlson, 2023).

Cows and horses feed off grassland pastures and hay

Wildfire smoke is thought to negatively affect plant growth by reducing sunlight and dropping smoke products but research is limited (Kienlen, 2019).

Hypothesis

Wildfire smoke will reduce germination rates because of smoke blocking sunlight leading to lowering soil temperature. Plants will have reduced growth because of lowered photosynthesis. Smoke could also negatively impact development due to chemicals in the air.

Procedure:

Plant 12.6g grass each in 2 separate identical containers beside each other. Apply smoke to one container daily by burning 0.31g of commercial compressed wood pellet (Traeger) for nine days.

Measure germination rates by counting each shoot of grass.

Remove grass to measure shoot and root length.

Prepare anatomy slides of fresh mount and thin sections (histology). Fresh mounts are cut on slides, stained with toluidine blue O (TBO) for 10s, rinsed and observed. Thin sections are fixed in 4% paraformaldye, dehydrated in ethanol and xylene then embedded in wax. Thin sections were cut with a hand microtome and stained with TBO.

Slides were observed with a light microscope for differences in development.

Repeat the process five times.

Materials:

Growing and Treating plants

2 containers (20 litres with lid)

Potting soil (1.5L)

1 tbsp. grass seeds (12.6g)  (Scotts Turf Builder Canada No.1 Lawn Mixture)

Wood pellets (0.31g)

Torch

Bowl

Recording Results

Sharpie

Paper

Phone (for pictures)

Fresh Mount and Histology

Sample Vials

Sharpie

Scotch Tape

4% Paraformaldehyde

Ethanol 99.99%

Xylene 99.99%

Vacuum chamber (Vevor)

Ice Cube Tray

100% Paraffin Wax

Hand Microtome

Stainless Steel Razor Blade

Black Piece of Cardboard

Oven (90°C)

Toluidine Blue (TBO)

Glass Slides

Coverslips

P.V.A Glue

Paper Towel

Microscope

Results

Germination rates: smoke treated germination rates (313±2.8 per 12.6g) were significantly lower than Control germination rates (359±11.3 per 12.6g)

Shoots and root length: Growth was reduced with smoke treatment for roots (16±7.8mm) and shoots (37±17.8mm) compared to control roots (21±8.9mm) and shoots (56±19.2mm). ANOVA smoke treatment probability was significant for shoots p=3.84x10-3  and for roots p=1.63 x 10-7.

Plant development: Roots were less developed with smoke treatment, showing poor separation of root cap and less organized tissue development. Leaves did not appear to different in tissue development with smoke treatment, but did have smaller cell size (0.022±0.006mm height, 0.017±0.005mm width) compared to control (0.058±0.016mm height, 0.053±0.018mm).

Conclusion

Smoke decreased gemination by 16%.

Smoke significantly reduced the growth of roots and shoots.

Smoke disorganized cells in the root tip and shortened cell size in the shoot.

Wildfire smoke negativity affects grass.

Our hypothesis is supported.

Analysis

Germination rates were significantly lower with smoke treated seeds.  Wildfire smoke may reduce the amount of grasses that germinate, which will cause lower crop yields.

Growth was significantly reduced with smoke treatment. Control plants grew longer shoots and roots compared to smoke treatments. Larger shoots will collect more sunlight for photosynthesis and larger roots will collect more nutrients. In a country with a short growing season, such as Canada, this head start would be difficult to overcome. Wildfire smoke will result in smaller plants, that may mean lower yields.

Development was significantly affected.  Smoke treatment resulted in smaller leaf cells and less organized roots. Wildfire smoke could negatively affect plant development. Tissue not organized as well may not function as well. Plants with unusual growth may not function as normal. This is evidence of plants less likely to perform well as crops.

Grass germination, growth and development are negatively affected by wildfire smoke. This may reduce the amount of crops produced. For growers, this means less income. For consumers this means more expensive food due to scarcity.

Further Research

Procedure improvements: Anatomy differences can be subtle and subjective making it hard to show your answer in numerical values- more histololgy repeats with different plant parts will help.

Environmental factors: Temperature, humidity, Ph levels could be mechanisms for the wildfire smoke effects. Preliminary work shows small differences- could these add up significant differences?

Application: What can prevent wildfire smoke damage? Can grass recover from smoke damage? Strategies need to be developed to prevent the negative effects of wildfire smoke on crops. Smoke treated plants had higher amounts of carbon and nitrogen uptake- could this be used?

Acknowledgments

I would like to thank my family. Mom, for the working space. Dad for helping me all along the way. Melody for reminding me to work harder and reminding me to do important things. Alex for the energy.

Thank you Isotope Science Laboratory, University of Calgary, for the percent nitrogen and carbon tests.

References

Bloomfield, J. A., Rose, T. J., King, G.J. (2014). Sustainable harvest: managing plasticity for resilient crops. Plant Biotechnology, 12: 517-533.

Canada Commons. (2026). Grasses. Retrieved from https://canadacommons.ca/topics/grasses/

Canadian National Fire Database (CNFDB). (2026). Retrieved from https://cwfis.cfs.nrcan.gc.ca/ha/nfdb

Carlson,L. (2026). The Economic Impact of Cereal Grains on the Canadian Economy. Retrieved from: https://cerealscanada.ca/wp-content/uploads/2023/10/18880-CCAN-InfoSheet-Economic-ImpactSK-Oct2023-3.pdf

Gokcinar photo. (2026). Wheat Grain and Flour in Petri Dishes. [Photograph]. https://www.pexels.com/photo/wheat-grain-and-flour-in-petri-dishes-30580656/

Hinkelmann, K., Kempthorne, O. (2005). Design and Analysis of Experiments, Volume 2: Advanced Experimental Design. John Wiley. p. 213.

Kienlen, A. (2019). Impact of smoke on crops is more than a little hazy. Retrieved from https://www.albertafarmexpress.ca/news/impact-of-smoke-on-crops-is-more-than-a-little-hazy/

Khakimov, T. (2026). Close-Up Shot of Person Holding Wheat. [Photograph]. https://www.pexels.com/photo/close-up-shot-of-person-holding-wheat-6412635/

Lowery, K. (2026). Fire at Night. [Photograph]. https://www.pexels.com/photo/fire-at-night-19926831/

Qin, H., Ma, C., Zhou, Y., Miao, Y., Huang, Y. (2020). Molecular Modulation of Root Development by Ethylene.  Small Methods, 4: 1900067-1900074.

Yeung, E. C. (1998). A Beginner’s Guide to the Study of Plant Structure. Tested studies for laboratory teaching. S.J. Karcher ed. Vol. 19. pp. 125-142.