Climate change

What causes stress in plants?

Doesn’t it seem that the older we get the more stressed our lives become? We are told constantly by doctors and the media how dangerous stress is to our health. We can read about different tools or techniques that helps reduce stress in our lives so that we can live happier and longer.

Infographic about plant stresses like water and temperature extremes, insects, etc.

Causes of plant stress vary but researchers are finding ways to help plants survive under many conditions.

But did you know that plants get stressed too? They’re not too concerned with deadlines, or who’s picking up Jonny from soccer practice. Their stress comes from environmental triggers that can negatively impact their health.

Unlike humans who can move out of the sun and into the shade if they get too hot, a plant doesn’t have that luxury. And, unlike plants, most humans have access to water when they need it1. Again, a plant relies on the environment and humans to provide water. Plants have learned how to manage a number of environmental factors, good and bad, that allows them to grow and produce a bountiful harvest.

small corn plants in flooded fields

Too much water can be even more stressful to plants than drought. Credit: Gurpreet Kaur

You might not be too surprised at what causes stress in plants. Many would have a similar effect on us if we were forced to endure them day-in and day-out. Let’s review the top plant stresses:

  1. Temperature can have a role in causing stress in plants. If you were forced to live outside you would have heavier clothes on during the cooler spring months. Then you would shed your coat and hat as the temperatures began to rise. What would you do if a sudden cold snap hit? Or if you were in the midst of a mid-summer heat wave?  Not having the recourses, such as warmer clothes or potable water, would lead to stress during that time.

This is no different for plants.  If a sudden frost hits young leaves or a heat wave hits mid-way through the growing season, plants need to be able to respond rapidly to protect their leaves and roots from these extreme changes in temperature.

Some plants have developed thick coatings on their leaves to adapt to environmental stress. Others are better at opening and closing their stomata – pore-like structures on their leaves that help regulate temperature as well as water content.

  1. Water resources for plants can be a bit of a Goldilocks situation. Too much (floods) or too little (drought) are bad – and “just right” depends on the plant. Too much rain can also stress plants as flooded conditions reduce the amount of air in the soil structure. Plants get much of their oxygen from pores in the soil – which are filled with water instead during flooded conditions.

Droughts and floods alter how well the roots can absorb and move nutrients within its tissues.   This reduction in nutrient mobility throughout the plant can introduce yet another type of stress.

  1. Chemical stresses can vary. Some soils are contaminated with other chemicals, like heavy metals or petroleum products, and this causes stress in many plants. Inconsistent fertilizer applications can also lead to stress as too much or too little fertilizer reduces yields. Too much fertilizer can mean nutrients and water are shipped to areas such as leaves, pulling nutrients away from fruit or grain development. This leads to larger plants with lower yields. Too little fertilizer will leave the plant deficient and small, making it unable to perform as well, again, reducing the final yield.

    orange and black corn rootworm bug on corn leaf

    Western corn rootworm can devastate a grower’s yields. Credit: Hannah Meyer

  2. Insect stress is something I can relate to! In northwest Ohio during the late spring and summer, we have ideal conditions for mosquitos. Those little critters can cause a lot of irritation and stress if you’re not prepared for them. Many insects and larvae feed on plant leaves and some can even transmit diseases to the plant.
  3. Microbial stresses include mildews and other fungal infections. There are also long list of viral and bacterial diseases that affect plants. The Irish Potato Famine was caused by a fungus.
  4. Weed stress from other plants is harmful to crops as well. Weeds can block sunlight from plants by growing taller. They steal nutrients and water from crops. That’s a lot like someone stealing your lunch from the school cafeteria or office refrigerator.
    woman in lab mixing silicon salts into soil

    Saebyul Kim, a student working in Zellner’s lab, mixes silicon compounds into growing media. Credit: SV Fisk

    Striga is a semi-parasitic weed.

There are many techniques that we as humans can use to reduce stress, the first few are simple: get plenty of sleep, drink lots of water and eat a healthy, balanced diet. Did you know that these steps can also help plants deal with stress? When plants live in healthy soil – full of nutrients and a diverse mix of soil microbes, the plants are healthier too.

My research focuses on one main component often missing from the healthy, balanced diet of a plant called silicon. This element, when absorbed by the plant, helps protect it from many of the stresses mentioned. However, just feeding the plants silicon won’t completely alleviate stress. We’ve also researched the best way to get plants to absorb silicon. We’ve also studied how plants absorb silicon.  Root proteins responded to silicon-rich and silicon-poor environments indicating that roots absorb silicon more efficiently than leaves.

Silicon application is only a portion of the tools and techniques needed to help plants grow productively. Growers need to think about all the factors that will reduce their crops’ productivity. Silicon is a vital nutrient plants absorb to boost their immune response and reduce the stressful impact of an ever changing, unpredictable environment.

Wendy Zellner, University of Toledo

Click here learn more about Zellner’s research on silicon’s ability to reduce plant stress.

  1. The UN estimates 2.1 out of the 7.4 billion people around the world are without access to clean water. (http://www.un.org/en/sections/issues-depth/water/)

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