# Biostimulant Potential of Aquatic Plants: Investigating Egeria densa and Other Macrophytes’ Potential in Crop Growth

## TL;DR

This study explores how aquatic plants like Egeria densa can boost crop growth as natural biostimulants, with optimal results observed at specific doses.

## Contribution

The study identifies Egeria densa as a promising biostimulant and provides dose-response data for its agricultural application.

## Key findings

- Ethanolic extracts of Typha domingensis and Egeria densa increased biomass, especially in Urochloa decumbens.
- Egeria densa ethanolic extracts at 1–2 kg/ha improved Phaseolus vulgaris height and biomass by 15%.
- Higher doses of Egeria densa extracts showed diminishing returns in crop growth.

## Abstract

This study investigates the potential of macrophytes as biostimulants in agricultural applications through a two-stage experimental approach. In the first stage, a screening experiment evaluated 12 macrophyte species using ethanolic and potassium chloride extracts at two doses (1 and 5 kg fresh biomass/ha) applied to bioindicator species Cucumis sativus (C3) and Urochloa decumbens (C4). Controlled greenhouse conditions and randomized block designs ensured reliability. Dry biomass was measured 21 days after treatment (DAT), revealing varied macrophyte effects. Ethanolic extracts of Typha domingensis and Egeria densa demonstrated significant biomass increases, particularly for U. decumbens, while potassium chloride extracts often reduced biomass. E. densa was selected for further analysis due to its promising results and ease of selective harvesting. In the second stage, a dose–response experiment assessed the impact of E. densa ethanolic extracts on Phaseolus vulgaris at six doses (0.25 to 4 kg fresh biomass/ha). Optimal results were observed at 1–2 kg/ha, yielding 15% increases in plant height and dry biomass. Higher doses showed diminishing returns. These findings highlight the potential of E. densa as a sustainable biostimulant and a solution for macrophyte overabundance in Brazilian reservoirs, supporting agricultural and environmental objectives.