Certified Crop Advisor Practice Exam

What can be found in air levels that can damage crops?

1. Ozone

2. PAN

3. Sulfides

4. Nitrogen dioxide

The correct answer is: PAN

The presence of photochemical oxidants like PAN (Peroxyacetyl Nitrate) in the air can significantly harm crops. PAN is formed from the reaction of nitrogen oxides and volatile organic compounds under sunlight, and it is particularly known for its phytotoxic effects. When crops are exposed to PAN, it can lead to reduced growth, leaf damage, and overall decreased crop yield. Its toxicity primarily stems from its ability to penetrate plant tissues and disrupt physiological functions, leading to failures in processes such as photosynthesis. Ozone, sulfides, and nitrogen dioxide also have the potential to negatively impact crops, but their mechanisms and effects differ. Ozone can cause visible injury to leaves, nitrogen dioxide can lead to nitrogen-induced stress, and sulfides can lead to plant toxicity. However, PAN is particularly noted for its specific damaging properties and the challenges it presents to plant health in certain conditions. Each of these compounds plays a role in the complex dynamics of air quality and its agricultural impacts, but PAN stands out for its acute phytotoxicity under urban and industrial pollution scenarios.