Olive Oil for Dressing Plant Leaves so as to Avoid O3 Injury

Abstract

The persistence of high ground-level ozone (O3) concentration in most regions of the northern hemisphere has severe implications to crop production, wild plant conservation, and forest sustainability. Therefore, methods for plant protection against O3 and O3 biomonitoring are of high relevance; however, there is not a method that can be applied in cultivations, which are intended for human consumption. After spraying bean (Phaseolus vulgaris L. cv. Pinto) seedlings with ethylene diurea, olive oil, or myclobutanil and exposing them to O3-enriched air (90 nmol mol−1) for a week (8 h day−1), we found that commercial olive oil can be effectively used as a protectant of plants against O3. This protection is attributed to avoidance of O3 uptake into the mesophyll, via decreased stomatal conductance. Olive oil can be applied even in organic cultivations, either for biomonitoring purposes or for short-term protection of plants during O3 episodes. Further studies are needed in order to investigate potential direct reaction of O3 with olive oil. Yet, attention should be paid when myclobutanil is applied to plants which are used for O3 biomonitoring purposes due to potential confounding effects by increasing O3-caused visible injury to plant leaves.