# Valorization of Posidonia oceanica Biomass Extract as an Elicitor to Mitigate Aphid-Induced Stress in Sweet Pepper Plants

## TL;DR

This study shows that extracts from Posidonia oceanica seaweed can help sweet pepper plants resist aphid damage by reducing stress and boosting plant health.

## Contribution

The study identifies an effective extraction method and demonstrates the efficacy of Posidonia oceanica biomass as a natural elicitor against aphid stress.

## Key findings

- Both doses of the extract reduced H2O2 and malonaldehyde levels, indicating lower oxidative stress.
- The extract maintained cell membrane integrity and photosynthetic activity in treated plants.
- Fresh and dry weight, along with cellulose and hemicellulose concentration, increased in treated plants.

## Abstract

The increased restrictions on the use of synthetic pesticides have made the application of substances that induce plant defense mechanisms an effective alternative for protecting plants while minimizing environmental and health risks. One of the most damaging pests for sweet pepper production is the infection by the green peach aphid. This study determined the best extraction method from Posidonia oceanica waste and evaluated its efficacy against Myzus persicae (Sulzer) aphid-induced stress. In particular, the foliar application of the extract at two different doses was investigated on sweet pepper plants. The results showed that both doses decreased the contents of H2O2 (40.8% and 56.3%, respectively) and malonaldehyde (31.1% and 39.9%, respectively) in plant tissue, indicating a reduction in oxidative stress. Additionally, these elicitor extracts were effective in maintaining cell membrane integrity and photosynthetic activity. This resulted in an increase in fresh and dry weight, as well as in cellulose and hemicellulose concentration. In conclusion, Posidonia oceanica extracts are a promising organic farming-treatment to fight against aphid pest and its ability to stimulate plant self-defense mechanisms.