07/28/2026
Is smoke harmful to potato plants? The answer may surprise you. IT DEPENDS!
“Some potato growers have speculated that wildfire smoke is limiting yields by slowing photosynthesis. They may be right; however, quantifying the effects of smoke on photosynthesis is complex and depends on many details (plant species involved, quality of the smoke, etc.). It is more practical to consider its effects in general terms. The main factors that affect the rate of photosynthesis are light intensity, carbon dioxide concentration and temperature; whichever of these factors is most limiting will determine the rate. This is called the law of limiting factors. Smoke can affect these limiting factors in different ways, some positive for plant productivity and some negative.
- Light intensity is reduced by smoke, but smoke almost never completely blocks the sun’s rays. How dark it gets depends on the components of smoke and how much they are absorbing light or scattering it. Smoke with a lot of soot tends to absorb light, while smoke with ash and other light-colored particles tends to reflect it like clouds.
- Carbon dioxide levels are dramatically increased by wildfires, and increased carbon dioxide usually leads to an increased rate of photosynthesis because normal atmospheric levels tend to be limiting. Ambient levels of carbon dioxide are estimated to be about 400 parts per million (ppm), but many plants will not reach their maximum uptake until closer to 1,000 ppm.
- Air temperatures are often moderated by smoke. Since the optimal temperature for potato photosynthesis peaks around 90 degrees Fahrenheit, the smoke cover may be a positive factor for plant productivity if it helps to curb temperatures when they would otherwise be very hot.
According to this assessment, light is the most limiting factor for photosynthesis when there is smoke. But the degree to which smoke limits photosynthesis and potato yields will depend on how dark it gets and how long the smoke persists. This is an oversimplification of the influences smoke can have on photosynthesis, since we should also consider that the chemical constituents of smoke can damage plant functions at a cellular level. And we need to recognize that plants can modify leaf structure (orientation, chlorophyll content, etc.) to maximize light captured under low light conditions when they are given some time to adjust.” (Carrie Huffman Wohlebin Potato Grower Magazine April 2022)
Click on the link to read the full article by Carrie Huffman Wohleb in the Potato Grower Magazine.
https://www.potatogrower.com/2022/04/seeing-through-the-haze
Impacts of wildfire smoke on potatoes
