Combination of humic biostimulants with a microbial inoculum improves lettuce productivity, nutrient uptake, and primary and secondary metabolism

Abstract

Background and aims Biostimulants of natural origin represent a growing ecological strategy to increase crops productivity, especially when applied in combination with microbial bioeffectors. We studied the effect of biostimulants such as Potassium Humates (KH) from Leonardite and Compost Tea (CT) from green compost on both productivity and nutritional status of lettuce plants, as well as on the primary and secondary metabolism of treated plants, when amended either alone or in combination with a commercial microbial inoculum (M+), mainly based on arbuscular mycorrhizal fungi (Micosat TabPlus). Results The biomass production as well as the uptake of both macro- and micronutrients by lettuce plants significantly increased when amended by the mixture of both humic materials (MIX) combined with the microbial inoculum. Similarly, the synergic MIX_M+ treatment significantly affected both the primary and secondary metabolism of lettuce more than their individual applications, by increasing, respectively, the biosynthesis of essential amino acids and carbohydrates, and that of antioxidant polyphenolic compounds, such as hydroxycinnamic acids, flavonols and coumarins. Conclusions Our findings suggest that a calibrated mixture of humic bioactive molecules in combination with microbial consortia represents a potential tool to improve crop productivity and its nutritional and metabolic status.

Glutamate, Humic Acids and Their Combination Modulate the Phenolic Profile, Antioxidant Traits, and Enzyme-Inhibition Properties in Lettuce

“…Accordingly, treatment with GA and GA + HA resulted in a significant accumulation of flavanols. Similar results were highlighted by Savarese et al [43], where the use of HA in combination with a microbial inoculum on lettuce significantly affected both primary and secondary metabolism, increasing the biosynthesis of essential amino acids, carbohydrates, and polyphenolic compounds.…”

Trace Element Contents in Maize following the Application of Organic Materials to Reduce the Potential Adverse Effects of Nitrogen

“…Numerous studies have confirmed the beneficial effects of HA and FA on plant yielding [35], nutrient metabolism, and the synthesis of compounds involved in plant adaptation to stress factors [28,33,36]. What is more, humic substances promote seed germination and seedling development [37,38] and root growth [39,40] and increase the cell membrane permeability and stimulate the synthesis of nucleotides [41], chlorophyll [42], proteins, and monosaccharides [35]. Thanks to its ability to bind and precipitate harmful substances, soil humus also serves a protective function in the environment [43] and affects the behaviour and availability of trace elements in the soil [44].…”

“…They mainly increase the phytoavailability of phosphorus, potassium, magnesium, iron, and zinc [33,34]. Numerous studies have confirmed the beneficial effects of HA and FA on plant yielding [35], nutrient metabolism, and the synthesis of compounds involved in plant adaptation to stress factors [28,33,36]. What is more, humic substances promote seed germination and seedling development [37,38] and root growth [39,40] and increase the cell membrane permeability and stimulate the synthesis of nucleotides [41], chlorophyll [42], proteins, and monosaccharides [35].…”

Humic substances from composted fennel residues control the inflammation induced by Helicobacter pylori infection in AGS cells

“…Lastly, additional in vivo studies are needed to confirm the efficacy of HS-FEN, in order to verify the potentiality of humic substances from composted green biomasses, not only in agricultural sector as biostimulants [67], but also in medical field.…”