Lemna minor as a model organism to evaluate seaweed biostimulants for hydroponic crops

Seaweed-based biostimulants (SBB) have emerged as sustainable alternatives for traditional soil-based agriculture and have garnered worldwide attention in recent years. Despite their growing popularity, there is limited information available on the application and efficacy of SBB in hydroponic crops. This study assesses the biostimulant effects of a commercial SBB using Lemna minor as a model organism, developing a standardized bioassay for evaluating SBB in hydroponic cultures. The experiment was carried out under controlled conditions, following a randomized design with 10 treatments. These treatments included SBB (0T1, 0.5T1, 2T1) alone at concentrations of 0, 0.5, and 2.0 mg/L, SBB (0T2, 0.5T2, 2T2) + Hoagland and Arnon nutrient solution, and SBB (0T30, 0.5T3, 2T3) + 2.5 g/L NaCl. A control group (0TC) with distilled water was also included. The results showed that the isolated SBB did not significantly differ (p > 0.05) from the control treatment. Treatments in group T2 had significantly higher coverage area compared to treatments in group T3. The highest absolute percentage of coverage area was observed in 0.5T2 (14.0 ± 1.2%). Regarding the specific growth rate SGR, the higher growth rates were observed in 0.5T2 (0.37 ± 0.02% day⁻1). Group T2 treatments exhibited significantly higher dry biomass (p < 0.05) than group T3 treatments. Treatment with NaCl hindered plant growth. This methodology could enhance the development of a robust protocol for evaluating seaweed biostimulants for hydroponic crops. Keywords: biostimulants, duckweed, seaweed extract.