Physiological and Biochemical Effects of an Aqueous Extract of Lemna minor L. as a Potential Biostimulant for Maize

Abstract

Biostimulants are receiving increasing attention for their beneficial effects on crops, driving interest in identifying new plant extracts that could exert such stimulatory effects. This work aimed to evaluate the potential of an aqueous extract obtained from duckweed (Lemna minor L.), a freshwater species, to act as a biostimulant in maize. For this purpose, duckweed plants were collected from a natural basin and then transferred, stabilized, and grown under controlled conditions. The duckweed extract was first characterized through untargeted profiling, which revealed an abundance of bioactive phytochemicals. A relatively high amount of low-molecular-weight secondary metabolites such as phenolics (6714.99 mg kg−1) and glucosinolates (4563.74 mg kg−1) were present in the plant extract. Maize seeds were primed with different concentrations of this extract (0.01%, 0.05%, 0.50%, and 1.00%, dry weight/water volume), and some physiological and biochemical traits of the crop were recorded. The duckweed extract improved maize germination, biomass, leaf area, pigment content, and vigor index. The most effective treatment was the 0.50% concentration, which improved the majority of the measured growth traits. The extract at concentrations of 0.05%, 0.50%, and 1.00% stimulated the assimilation of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), iron (Fe), and copper (Cu). In summary, this study revealed that duckweed is a promising species that can be cultured and grown under controlled conditions for obtaining extracts with biostimulant properties.

Biostimulant Effects of an Aqueous Extract of Duckweed (Lemna minor L.) on Physiological and Biochemical Traits in the Olive Tree

“…In general, no studies have investigated the effects of plant extracts obtained from freshwater aquatic species except for a recent one on Lemna minor L. (duckweed), which showed the biostimulant potential of this plant in maize [26]. In particular, the beneficial effects of the duckweed extract, found in this study, were attributed to the high abundance of phytochemicals with bioactive properties [26].…”

“…The phytochemical profile of the duckweed extract was characterized through an untargeted metabolomics approach, based on ultrahigh-pressure liquid chromatography quadrupole-time-of-fight mass spectrometry (UHPLC-ESI/QTOF-MS) as reported by Del Buono et al [26]. Briefly, the chromatographic separation was achieved using an Agilent Zorbax eclipse plus column (50 × 2.1 mm, 1.8 µm) and a binary mixture of water and acetonitrile (4-96% in 33 min linear gradient).…”

“…The annotation of raw mass features was performed as previously reported using the software Profinder B.07 (from Agilent Technologies, CA, USA), according to monoisotopic accurate mass and the whole isotopic pattern [26]. The subsequent annotation was carried out using the plant metabolome database PlantCyc (https://plantcyc.org/ access date: 14 October 2021), and only the compounds annotated within 100% of replications were retained and annotated.…”

“…In a previous study [26], duckweed extract was quantitatively analysed to determine phenolics and glucosinolates content and identify other bioactive compounds. In the present study, a broader screening of metabolites of the aqueous duckweed extract was performed using a plant metabolome database to comprehensively highlight the molecules that may help explain the extract biostimulant capacity (Supplementary Table S1).…”

“…Lemnaceae are plants rich in metabolites that exhibit antioxidant and antibacterial properties [29]. In addition, duckweed has been recently demonstrated to possess a high content of phenolic acids, phenols and flavonoids [26,30]. It is well known that certain compounds could benefit plants when exogenously applied [31].…”