# Selenium Biofortification and an Ecklonia maxima-Based Seaweed Extract Jointly Compose Curly Endive Drought Stress Tolerance in a Soilless System

## TL;DR

This study shows that combining seaweed extract and selenium can help curly endive plants tolerate drought stress in soilless systems.

## Contribution

The novel approach combines seaweed extract and selenium to enhance drought tolerance in curly endive.

## Key findings

- Drought stress reduced plant growth and water content but increased dry matter and stress markers.
- SwE, Se, and their combination improved growth and reduced stress markers compared to the control.
- Combined SwE + Se application is effective for moderate drought stress mitigation in curly endive.

## Abstract

Vegetable cultivation is currently facing complex challenges related to climate change, with negative repercussions on plant performance. In this scenario, the employment of eco-friendly agronomic tools capable of boosting plant tolerance to abiotic stresses is fundamental. Among them, the use of non-microbial biostimulants, such as seaweed extracts (SwEs), and microelements, like selenium (Se), is considered an efficient approach to overcome abiotic stresses. In this experiment, the performance of chicory plants cultivated under three different irrigation levels (100%, 75% or 50% of substrate water holding capacity) and treated with SwE, Se or their combination (SwE + Se) was evaluated. The results revealed that drought stress significantly decreased growth, productivity and relative water content but increased soluble solid content, dry matter percentage, and proline and malondialdehyde concentrations. The application of Swe, Se or Swe + Se enhanced growth, productive features and soluble solid content and reduced dry matter percentage, proline and malondialdehyde compared to the control. Based on our results, Se and SwE combined application could be a valuable approach to face moderate drought stress on curly endive plants and improve productive and quality traits.