Bioactivity of humic substances and water extracts from compost made by ligno-cellulose wastes from biorefinery

Quantitative Structure-Activity Relationship of Humic-Like Biostimulants Derived From Agro-Industrial Byproducts and Energy Crops

“…Conversely, both AD and MG contained larger methoxyl groups than the other HLS, with the exception of EUC, whose methoxyl amount was comparable to that of AD ( Table 1). The O-alkyl groups, usually associated with the resonance of carbons in lignin lateral chains and carbohydrates, were larger in CAR-and LIM-derived materials (Robert, 1992;Spaccini et al, 2019). Furthermore, the occurrence of carbohydrates is confirmed by NMR signals in the 90-110 ppm range, attributed to the resonance of anomeric carbons ( Table 1).…”

“…Both HS and HLS are reckoned to boost crop growth and yields, and protect plants from abiotic stresses, by triggering specific metabolic routes (Aguiar et al, 2016;Khaleda et al, 2017;Vinci et al, 2018). HS and HLS have also been applied to seeds or hydroponically-grown plants to study their bioactivity without the environmental complexities of field trials (Ertani et al, 2013;Savy et al, 2018;Spaccini et al, 2019).…”

Bio-Based Hydrogels Composed of Humic Matter and Pectins of Different Degree of Methyl-Esterification

“…However, they could also directly act as plant biostimulants because of the presence of bioactive humic substances and lignocellulose residues. In fact, both HS from compost and HULIS from biorefinery lignocellulose residues were found to be active as plant biostimulants [25,26], and their application to soil was shown to improve soil physical and chemical properties, crop production [27], and macronutrient availability [28]. HS and HULIS are regarded as supramolecular associations of heterogeneous and relatively small molecules, which are held together in only apparently large molecular sizes by weak forces, such as hydrogen and hydrophobic bonds [29], and whose conformations can be disrupted by the action of weak organic acids [30], thereby allowing the release of organic bioactive molecules and nutrients [31].…”

Active chemical fractions with high fungistatic activity of humic‐like substances obtained via different extraction solvents

“…Many factors can lead to diversity in chemical structure, such as chemical modifications, multi‐origin materials and pretreatments . Variations in chemical structure derived from different extraction solvents [sodium hydroxide (NaOH) and water] have also been found by Spaccini et al . In previous studies, inorganic solvents, such as NaOH and potassium hydroxide (KOH), have been widely used in the extraction of HULIS, and organic solvents have also been introduced for HULIS extraction; but mixed extraction solvents with both inorganic and organic solvents have rarely been reported.…”

“…In the existing research, 13 C‐CP‐MAS NMR studies revealed that some organic carbon constituents were associated with the bioactivities (mainly auxin‐like activities) of HULIS. For example, aromatic and/or hydrophobic components were closely related to the bioactivity of maize root growth stimulation, whereas the phenols and lignin derivatives were associated with enhanced phosphorus uptake in maize . However, there are few studies about the relationships between the organic components in HULIS examined by 13 C‐CP‐MAS NMR and bioactivities against fungal pathogens (fungistatic activities).…”