Seaweed extract by microwave assisted extraction as plant growth biostimulant

Abstract

Microwave Assisted Extraction (MAE) was used to obtain aqueous extracts of Baltic seaweeds. Three different temperatures: 25, 40, 60°C were examined. Algal extracts were characterized in terms of polyphenols, microand macroelements, lipids content and antibacterial properties. This is the first study that examines the effect of algal extract obtained by MAE in plant cultivation. The utilitarian properties were checked in the germination tests on Lepidium sativum for three dilutions of extract (0.5, 2.5 and 10%). Results showed that the content of polyphenols in extracts decreased with temperature, whereas the content of micro-and macroalements increased with temperature. The aqueous extracts did not contain fatty acids and did not show inhibitory effect on Escherichia coli and Staphylococcus aureus. Germination tests showed that plants in the experimental groups with an optimal concentration of extract had a higher height, weight, chlorophyll and micro-and macroelement content than plants in the control group. The algal extracts did not significantly influence the morphology of plants as shown in SEM pictures. Results show that algal extracts obtained by MAE have the highest potential applied in agriculture as biostimulants.

The Quest for Phenolic Compounds from Macroalgae: A Review of Extraction and Identification Methodologies

“…Other parameters, namely SLr (1:40), extraction time (40 min), irradiation power (200 w) and temperature (50 • C) were also optimized in this study. The SLr used in MAE varied from low values, such as 1:3 [111] or 1:4 [108], to considerable higher ratios, such as 1:50 [109]. In a previous study it was verified that the TPC of Caulerpa racemosa MAE extracts increased more than fivefold when the SLr increased from 1:10 to 1:20, after which the increasing trend remains almost insignificant [109].…”

“…Table 4 summarizes the studies concerning the MAE extraction of phenolic compounds from macroalgae. Ethanol:water mixtures have been the most commonly used in MAE of phenolic compounds from macroalgae [108,109], although few authors have applied acetone:water mixtures [54], methanol:water [110], or just water [111]. Pérez et al studied and optimized the MAE of phenolic compounds from Sargassum muticum wet samples in two stages, with a solvent-free extraction followed by a water extraction, adding only the moisture content [112].…”

Chemical Characterization of Enteromorpha prolifera Extract Obtained by Enzyme-Assisted Extraction and Its Influence on the Metabolic Activity of Caco-2

“…The results obtained in the present study were compared with the multielemental composition of extracts produced from green Baltic macroalgae using SFE and MAE. Generally, for most of the elements, the extraction percentage from the raw biomass was lower than 10%, with the exception of Na for EAE; Cu, Mg, Na and S for SFE [27]; and K, Mg and Na for MAE [28]. …”

The Application of Homogenate and Filtrate from Baltic Seaweeds in Seedling Growth Tests

“…The results showed that the tested products can be a source of micro-and macro-elements in plant cultivation, especially algal homogenate that was rich in B, Fe, Mn, Zn, K, P, and S in contrary to algal filtrate. The results from the present study were compared with multi-elemental composition of algal extract obtained from the same algae using microwave assisted extraction (MAE) [30] and chemical hydrolysis with acidified water (pH 2) [36]. It was found that especially micro-elements were extracted more efficiently using mechanical processing than the mentioned physico-chemical methods.…”

“…In the case of soil application, the cotton wool was evenly moistened with the appropriate filtrates. In the foliar application, the seeds/seedlings were sprayed with the same volume of the appropriate filtrate [27,30].…”