Phytotoxicity is most often caused by which of the following during seed treatment?

• A. Poor compatibility between seed and coating.
• B. Seed dehydration during storage.
• C. Toxicity from sunlight exposure.
• D. High application rate.

Answer: (B)

Phytotoxicity from seed treatments is most tied to the seed’s moisture status. When seeds are dehydrated during storage, the protective balance around the embryo is stressed and the coating can become overly concentrated on the seed surface or develop cracks. That concentration or exposed tissue creates hotspots of chemical exposure as germination begins, injuring the seed or forming a weak seedling. Keeping seeds at proper storage moisture helps prevent these over‑exposed areas and reduces the likelihood of phytotoxic injury.

Other factors can contribute in specific cases—for example, poor compatibility between seed and coating can lead to uneven coverage, and very high application rates can increase toxicity risk—but the most common and general cause is seed dehydration during storage.