Commercial Biostimulant Research Articles

Potential of Kappaphycus alvarezii (seaweed) extract as biostimulant on the growth of mangrove propagules (Rhizophora mangle L.) through foliar application

This study investigated the potential of seaweed extract of Kappaphycus alvarezii as biostimulant in 3% concentration on the relative growth rate, net assimilation rate, and root to shoot ratio of mangrove propagules of Rhizophora mangle L. through different day- intervals of foliar application under field experiment. There were two factors included: factor A- types of treatment (A1- water, A2- seaweed extract, A3- commercial biostimulant); and, factor B- different day-interval of application (B1- 4 days, B2- 8 days, B3- 12 days). It was revealed that 3% concentration of seaweed extract of K. Alvarezii had no significant effect on the rate growth rate, net assimilation rate, and root to shoot ratio of mangrove propagules of R. Mangle L. Moreover, seaweed extract of K. alvarezii as biostimulant in 3% concentration had no significant difference to the commercial foliar biostimulant and to the different day- intervals of application. This study recommends to explore higher concentration of seaweed extract from K. Alvarezii on propagules of R. Mangle L. and other mangrove species in a greenhouse setting.

Effect of Mycorrhizal Inoculation on Melon Plants under Deficit Irrigation Regimes

The shortage of good quantity and quality of water for irrigated agriculture is a major problem in arid and semiarid regions. To deal with this problem, deficit irrigation (DI) or arbuscular mycorrhizal fungi (AMF) inoculation have been proposed and adopted for many crops as a tool to save water, or to improve crop tolerance to drought stress. An experiment was conducted for two consecutive years to evaluate the effect of mycorrhizal inoculation on the physiological, morphological, yield, and quality characteristics of melon plants grown under deficit irrigation. Melon crop (Cucumis melo L. cv. Helios) was grown under field conditions adopting a split-plot design with four replications, where DI was the main factor and AMF inoculation was the secondary factor. DI treatments consisted of applying 60%, 80%, or 100% of crop evapotranspiration (ETc) on melon plants inoculated or not with a commercial biostimulant containing 50% of Rhizophagus irregularis, and 50% of Funneliformis mosseae. Moderate and severe deficit irrigation significantly reduced the relative water content, stomatal conductance, yield, nitrogen applied efficiency (NAE), and fruit firmness of the uninoculated plants, but significantly increased irrigation water use efficiency (IWUE) and the ascorbic acid content of the fruit. AMF had a positive effect on plant tolerance to moderate water stress, and on some fruit quality parameters (fruit length, firmness, and sugar content). The combined use of moderate deficit irrigation (80%) and soil inoculation with AMF on melon plants allows water savings without affecting fruit yield, and increases IWUE, NAE, and some fruit quality characteristics (firmness, SSC, and SSC/TA). Furthermore, the use of AMF plants could be worth it to reduce the yield loss and increase fruit quality, even with severe deficit irrigation (60%).

Response of Winter Wheat (Triticum aestivum L.) to Selected Biostimulants under Drought Conditions

To prevent the staggering degradation of the environment, restrictions in the use of plant protection products and fertilizers are being strengthened every year. Therefore, methods for improving plant tolerance to unfavorable environmental conditions are sought to positively affect both plants and the natural environment. Here, we evaluated and compared the efficacy of four commercial biostimulants on the tolerance of winter wheat to drought stress. The effects of the following biological agents: Bacillus sp., soil bacterial strains, free amino acids, and humic substances on winter wheat were assessed in a pot experiment under full hydration soil moisture and under drought. Among the studied biostimulants, the two based on bacterial strains had the strongest beneficial effects on improving the tolerance of wheat plants to drought. In plants treated with either of these two, the highest level of CO2 assimilation was recorded under drought. Moreover, in the same plants, the decrease in transpiration value due to drought was the smallest. The highest stomatal conductance under drought was also noted in these same plants. The results of chlorophyll fluorescence also indicate the smallest damage to the photosynthetic apparatus in the plants on which these bacterial biostimulants were used. Under drought, the lowest initial fluorescence values were noted for these bacterial preparations, as were the highest values of maximum fluorescence. On the other hand, a parameter indicating stress was reduced due to drought in all plants, except for those treated with one of these preparations. Another parameter showing the efficiency of the use of light photons in the photosynthesis process increased only in plants treated with one of these preparations, whereas for other plants it decreased due to drought, with the smallest decrease observed in plants treated with the other preparations. The most effective work of the photosynthetic apparatus in such treated plants was observed by the fastest transport of electrons through photosystems under drought. Additionally, under drought, the highest grain yield was obtained in plants treated with one of these bacterial preparations. The drought stress resistance index indicated that among all tested formulations, plants treated with either of these bacterial preparations scored the best. The use of these two biostimulants is recommended for comparative efficacy studies in the field, to help combat the drought-related yield losses of wheat.

Changes in the Phytochemical Profile and Antioxidant Properties of Prunus persica Fruits after the Application of a Commercial Biostimulant Based on Seaweed and Yeast Extract.

Plant biostimulants are formulations that are experiencing great success from the perspective of sustainable agriculture. In this work, we evaluated the effect derived from the application of a biostimulant based on algae and yeast extracts (Expando®) on the agronomic yield and nutraceutical profile of two different cultivars ("Sugar Time" and "West Rose") of Prunus persica (peach). Although, at the agronomic level, significant effects on production yields were not recorded, the biostimulant was able to reduce the ripening time, increase the fruit size, and make the number of harvestable fruits homogeneous. From a nutraceutical point of view, our determinations via spectrophotometric (UV/Vis) and chromatographic (HPLC-DAD-MS/MS) analysis showed that the biostimulant was able to boost the content of bioactive compounds in both the pulp (5.0 L/ha: +17%; 4.0 L/ha: +12%; 2.5 L/ha: +11%) and skin (4.0 L/ha: +38%; 2.5 L/ha: +15%). These changes seem to follow a dose-dependent effect, also producing attractive effects on the antioxidant properties of the fruits harvested from the treated trees. In conclusion, the biostimulant investigated in this work proved to be able to produce more marketable fruit in a shorter time, both from a pomological and a functional point of view.

Bioestimulants on common bean (Phaseolus vulgaris L.) cultivar TAA Marhe in vitro

Plant biostimulants are substances that can increase plant germination growth, and development, acting on the stimulation of cell division. This study aimed to evaluate the in vitro action of two commercial biostimulants AgroRaiz® and Stimulate® on the physiological quality of seeds of Phaseolus vulgaris cultivar TAA Marhe. Seeds of the TAA Marhe cultivar were used at the usual concentration of both biostimulants AgroRaiz® 0.3 L 100 kg-1 and Stimulate® 0.5 L 100 kg-1 seeds. Classic germination test, dry matter, root length and accelerated aging test were performed. The experimental design was completely randomized with three treatments and four replications. The usual doses of biostimulators did not influence the germination rate and dry mass by the classical method; however, Stimulate® demonstrated action on mean root length. For the aging assay, AgroRaiz® proved to be superior to Stimulate® in germination and seedling dry matter.

Isolation and Characterization of Gibberellin (GA-3) from Banana Blossom of Musa balbisiana Colla and Effect of The Isolate Addition on The Growth of Soybean (Glycine max) Plant

There is a type of banana that is unique because the flesh is filled with black seeds locally known as “pisang batu” (Musa balbisiana Colla). The objective of research was directed to determine the content of GA3 in banana blossom of M. balbisiana Colla and its effect on the growth of soybean (Glycine max) plant in vegetative and generative phase. GA3 was prepared by maceration followed by extraction using ethyl acetate and further purified using adsorption column chromatography and preparative TLC. The isolated product was then characterized using FTIR and HPLC. Sprouts of soybeans with uniform height were planted on polybags containing a mixture of planting media (soil: husk: manure = 3:2:1). The sprout was divided into five groups. The first group is the control only spraying with water, while others groups were treated by spraying GA3 isolate, crude extract, commercial Biostimulant and 1% NPK fertilizer. The soybean was determined for chlorophyll content of the leaf, proximate content and α-amylase activity. The results of HPLC and FTIR on gibberelline isolates showed a retention time and wave number which is relatively similar to the GA3 standard. GA3 levels in banana blossom of M. balbisiana Colla were 2.55 mg/g dry weight. The results of research showed that the GA3 isolate, crude extract and commercial biostimulant have significant effects on the growth of soybean plant both in the vegetative and generative phases for each parameter determined, proximate content, chlorophyll content and α-amylase activity compared to the control and NPK fertilizer.

Effect of a Biostimulant Based on Polyphenols and Glycine Betaine on Tomato Plants’ Responses to Salt Stress

Climate change accentuates abiotic stress conditions putting at risk several commercial cultivars particularly vulnerable to salinity in the early stages of development, which makes adopting new technologies in tune with the environment necessary to mitigate its impact. In this study, we tested the possible effects of a commercial biostimulant (BALOX®) on enhancing salt stress tolerance in salt-treated tomato plants, analysing plant growth and several stress biochemical markers: photosynthetic pigments, ion contents in roots and leaves, leaf concentrations of different osmolytes, oxidative stress markers, non-enzymatic antioxidants, and the specific activities of major antioxidant enzymes. The experimental design consisted of three soil salinity levels (non-saline, saline, and very saline), two biostimulant doses (0.4 mL and 0.8 mL of the BALOX® stock per litre of irrigation water), and the non-treated control (without biostimulant), evaluated at 30 and 60 days of treatment. The biostimulant favoured plant growth, especially at the root level and in saline soils. In addition, it helped reduce Na+ and Cl− uptake by the roots and seemed to stimulate, to some extent, K+ and Ca2+ transport to the aerial part of the plant. The BALOX® application significantly reduced the level of stress affecting the plants in saline soils, as shown by the decrease in the contents of proline and oxidative stress biomarkers and the activity of salt-induced antioxidant enzymes. Some of the biostimulant effects were also observed under low salinity conditions; therefore, in addition to enhancing salt stress responses, BALOX® appears to stimulate the growth of tomato plants through a general improvement of photosynthesis and primary metabolism.

Protein Hydrolysates from Animal or Vegetal Sources Affect Morpho-Physiological Traits, Ornamental Quality, Mineral Composition, and Shelf-Life of Chrysanthemum in a Distinctive Manner.

Protein hydrolysates (PHs) are a prominent category of plant biostimulants, mainly constituted of amino acids, oligopeptides and polypeptides, obtained by partial hydrolysis of animal or plant protein sources. Despite scientific evidence supporting the biostimulant action of PHs on vegetables, the morphological, physiological, and shelf-life performances underlying the PH action on cut flowers are still poorly explored. Accordingly, the aim of this research is to assess the effects of three commercial biostimulants, one animal PH (PH A, Hicure®) and two plant PHs (PH V1, Trainer® and PH V2, Vegamin©), on two chrysanthemum (Chrysanthemum morifolium) cultivars (Pinacolada and Radost). In both cultivars, only the plant-derived PH (V1 and V2) treatments recorded significantly higher fresh plant biomass than the control (on average +18%, in both cultivars). The foliar application of the vegetal-derived PHs but not the animal one, particularly in Pinacolada, improved the status of plants, stimulating stem elongation and the apical flower diameter. In Pinacolada, applications with PH V1 resulted in a significant increase in nitrate and P concentration in leaves and Ca content in flowers compared with the control (+43%, +27%, and +28% for nitrate, P, and Ca, respectively). In Radost, PH A and PH V2 applications caused a significant reduction in nitrate concentration in both leaves and flowers compared with the control. One week after harvest, in both cultivars, PH A applications caused flower stems to wilt faster than the control. In contrast, plants treated with PH V1 revealed significantly slower flower stem senescence compared to the control. Flower wilting during vase life was correlated to a decrease in the K-to-Na ratio in flowers due to an inability to transport K to the flowers from the leaves rather than an increase in Na in the flowers themselves.

Foliar Applications of Humic Substances Together with Fe/Nano Fe to Increase the Iron Content and Growth Parameters of Spinach (Spinacia oleracea L.)

Iron deficiency, which severely decreases the plant yield and quality, is one of the major problems of calcareous soils. Foliar applications of humic substances and/or Fe fertilizers are environmentally friendly methods to cope with Fe deficiency. The aim of this study was to investigate the combined effect of Fe/nano Fe and humic/fulvic acid-based biostimulant foliar applications on the Fe content and plant growth parameters of spinach. Treatment solutions were prepared either by mixing a common Fe fertilizer, FeSO4·7H2O, with different commercial biostimulants (Fulvic-based: Fulvagra®, Fulvagra®WSG; Humic-based: HS300®, Humin Fe® and Liqhumus®, Grevenbroich, Germany) or by mixing nano ferrihydrite with different ratios of fulvic substance (FA-50, FA-75, and FA-100) and humic acid (Nano Iron). Growth parameters (plant fresh and dry weights, plant dry matter, root fresh and dry weights, root dry matter, leaf number per plant, and leaf area); chlorophyll reading value (SPAD); chlorophyll (a,b, and total) and carotenoid contents; and leaf and root mineral contents (N, P, K, Ca, Mg, S, Cu, Mn, Zn, B, active Fe, and total Fe) of samples were determined. Our results showed that foliar application of biostimulants together with Fe sources improved the nutrient uptake, chlorophyll contents, growth characteristics, and yield; however, not all humic substances had the same effect. When all parameters were considered, Fulvagra treatment—which contained 17% fulvic acid and microorganisms in its content together with 20 mM FeSO4·7H2O—was the most effective application, followed by FA100 treatment containing fulvic acid and 20 mM nano ferrihydrite. This finding indicates that fulvic acid containing biostimulants is more effective in foliar applications than humic-based biostimulants against Fe deficiency due to their low molecular weight which enables better penetration into the leaves. In conclusion, foliar applications of fulvic substances together with Fe fertilizers can be used to increase the Fe uptake of crops and the yields under Fe-deficient conditions.

Biostimulants combined with water soluble fertilizer had little effect on transplant growth and pepper yield grown under greenhouse conditions

ABSTRACT Information on benefits of commercial biostimulants is needed due to the lack of unbiased claims and increased interest and use of commercial biostimulants by growers. This study assessed growth, yield, and quality of bell pepper (Capsicum annuum L.), ‘Ace,’ grown using the commercial biostimulants (Bioyield®, Environoc 401®, MA Endomaxx®, Rootshield Plus + WP ®, Select®, and Spectrum+Myco®) and 2 concentrations of N fertilization. Transplant size was not improved by biostimulant treatment. At harvest, Environoc 401® and Select® caused production of more fruit with 50% or more color. Bioyield® reduced dry weight by ~25% with no reduction to yield. Microbial-based biostimulants inconsistently improved growth and quality of ‘Ace’ bell pepper under a greenhouse and commercial fertilizer program. Commercial biostimulants may prove their value with more applications prior to fruit set or in the field, where other yield limiting factors come into play.

Effects of cyanobacterial-based biostimulants on plant growth and development: a case study on basil (Ocimum basilicum L.)

In the coming years biostimulants will play a key role in the sustainable intensification of agriculture due to their capacity to improve crops quality, nutrient use efficiency and tolerance to abiotic stresses. Cyanobacteria are nowadays considered one of the most promising sources of new biostimulants; however, in vivo studies using cyanobacteria are still scarce and often limited to a few genera. In this work the biostimulant activity of five cyanobacterial hydrolysates was evaluated on Ocimum basilicum L. grown in hydroponics. Plants were treated weekly with foliar applications of the cyanobacterial hydrolysates and of two commercial products. Three of the tested cyanobacterial hydrolysates, administered at the concentration of 1 g L-1, were effective in increasing plant growth (up to +32%), and number (up to +24%) and fresh weight (up to +26%) of the leaves compared to controls. Moreover, the cyanobacterial hydrolysates performed better than the commercial biostimulants. The biochemical characterization of the hydrolysates suggests that the observed bioactivity can be related to a high carbohydrate content. Our results indicate that cyanobacteria-based biostimulants can be an effective tool for sustainably enhancing plant growth and yields.

Transcriptomic changes induced by applications of a commercial extract of Ascophyllum nodosum on tomato plants

Extracts of Ascophyllum nodosum are commonly used as commercial biostimulants in crop production. To further understand the seaweed extract-induced phenomena in plants, a transcriptomic study was conducted. RNA-seq differential gene expression analysis of tomato plants treated with a commercial A. nodosum extract formulation (Stimplex) revealed the up-regulation of 635 and down-regulation of 456 genes. Ontology enrichment analysis showed three gene categories were augmented, including biological processes, cellular components, and molecular functions. KEGG pathway analysis revealed that the extract had a strong influence on the expression of genes involved in carbon fixation, secondary metabolism, MAPK-signalling, plant hormone signal transduction, glutathione metabolism, phenylpropanoid and stilbenoid metabolism, and plant-pathogen interactions. qRT-PCR validation analysis using 15 genes established a strong correlation with the RNA sequencing results. The activities of defence enzymes were also significantly enhanced by seaweed extract treatment. Furthermore, AN-SWE treated tomato plants had significantly higher chlorophyll and growth hormone content and showed improved plant growth parameters and nutrient profiles than the control. It is postulated that seaweed extract-induced gene regulation was responsible for favourable plant responses that enabled better growth and tolerance to stress conditions. This study provides evidence at the transcriptomic level for the positive effects of foliar application of the Ascophyllum nodosum extract (Stimplex) observed in treated tomato plants.

‘TifEagle’ Bermudagrass’ Response to Commercial Biostimulants

Biostimulant use in the US is currently not regulated; therefore, much speculation exists as to product benefit claims. Three greenhouse trials were conducted with greens grade ‘TifEagle’ bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) Clemson, SC during 2019 and 2020. Trial one simulated recovery from “divot” injury while trial two simulated recovery following sod harvest and measured growin rate using either pure sand or a native soil. Trial three was a rooting experiment performed in lysimeters to ascertain root growth following biostimulant use. Three commercial biostimulants (EarthMAX, Worm Power, and Hydra-Enrich 20) were used for all three studies, each applied individually or, applied with an 18-3-4 fertilizer (named: “Fert”) at 0.2 lb N/1,000 ft2 (9.76 kg N/ha). Trial one measured normalized difference vegetation index (NDVI) ratings where EarthMAX (EM) (mean=0.576) had ~6.4%, ~3.3%, and 5.4% less recovery compared to untreated control, Hydra-Enrich 20 (HH) and Worm Power (WP), respectively. Similar results were provided from digitized photographs where EM+F (mean=0.586) treated turf recovery was ~7% less than fertilizer, and ~11% less than HH+F. Without additional fertilizer, EM (Mean=0.415) was significantly lower in coverage versus all other treatments, including untreated (~21%). From image analysis for trial two, the native soil plus fertilizer resulted in HH+F (Mean=0.375) being significantly less than EM+F (~17%), WP (~12%) and fertilizer (~13%). From NDVI ratings in trial three, EM (mean = 0.542) had significantly greater vegetative index than HH (~16%) and WP (~13%). Although, significant differences were technically recorded for the digital measurements, treatment differences were difficult to detect with the naked eye. Overall, positive results from ratings were only seen in turf subjected to extreme stress from the continual removal of roots every four weeks.

Optimization of the rope seeding method and biochemical characterization of the brown seaweed Asperococcus ensiformis

The consumption of seaweed has grown notably due to its use in the food, cosmetic and pharmaceutical industries, as well as organic fertilizers and biofuel, among others. Species of Asperococcus have antioxidant and antitumor properties and synthesize abundant amounts of fucoidans with important anticoagulant properties. In this study, the biochemical characterization of the A. ensiformis sporophytes was performed: organic matter, alginates, fucoidans, total carbohydrates and proteins content, pigments, polyphenols and antioxidant activity. Also, its life cycle was described and the best culture conditions were identified to optimize the hatchery phase. Three incubation temperatures 8, 12 and 16 °C and six nutrient concentrations were evaluated: three with Provasoli culture medium (PES) and three with PES + Kelpak® (a commercial biostimulant based on algae). Asperococcus ensiformis presented a heteromorphic life cycle, alternating between microscopical branched filaments (gametophytic phase) and an erect macroscopic stage (sporophytic phase). The biochemical composition of the A. ensiformis sporophytes showed a relatively low carbohydrate and protein content, but a high yield of alginates and fucoidans, and high polyphenol content and antioxidant activity. In the culture assays, the highest survival and colonization on seed-rope of gametophytes were achieved at 12 °C and high PES concentrations. The colonization of sporophytes on the seed-ropes at the end of the experiment was similar at the different temperatures, but the highest survival and growth were at 8 °C and low PES and PES + Kelpak® concentrations. This study emphasizes the need to analyze the industrial potential of A. ensiformis, through its biochemical characterization and optimization of crops, using different temperatures and traditional nutrients, as well as biostimulants based on seaweeds.

Influence of Commercial Seaweed Extract and Microbial Biostimulant on Growth, Yield, Phytochemical Content, and Nutritional Quality of Five Abelmoschus esculentus Genotypes

Biostimulant application during the cultivation of underutilized crops is an environmental-friendly approach for their production and utilization to promote food security and human health. This study investigated the effect of two commercial biostimulants (a seaweed-based extract, Kelpak® (1:100, 1:40, and 1:20, dilutions), and plant growth promoting rhizobacteria, PGPR (1:5, 1:10, and 1:15, dilutions)) on the growth, yield, phytochemical content, and nutritional quality of five selected Abelmoschus esculentus genotypes. Biostimulant application significantly influenced vegetative growth and yield in a dose-dependent manner. Plant height, chlorophyll content, stem diameter, number of pods, and total pod fresh and dry weights increased with a decrease in dilution of the biostimulants. The application of PGPR (1:5) significantly promoted both the vegetative growth (plant height, chlorophyll content, and stem diameter) and yield (number of pods, total fresh weight, and total dry weight) when compared to the control (untreated plants) and other biostimulant dilutions. Genotype and biostimulant application had an interactive effect on all the phytochemical (total phenolics, flavonoids, and condensed tannins) and nutritional (β-carotene, vitamin C, calcium, iron, potassium, magnesium, sodium, and zinc) qualities evaluated. This study demonstrated the differential effect of biostimulant application on A. esculentus genotypes. These biostimulants can be used to enhance growth, yield, biochemical, and nutritional contents of underutilised crops such as A. esculentus, depending on the crop genotype, in order to improve crop productivity and combat food insecurity especially in food insecure communities.

Pathogenic potential of bacteria isolated from commercial biostimulants

Microbial-based products are a promising alternative to agrochemicals in sustainable agriculture. However, little is known about their impact on human health even if some of them, i.e., Bacillus and Paenibacillus species, have been increasingly implicated in different human diseases. In this study, 18 bacteria were isolated from 2 commercial biostimulants, and they were genotypically and phenotypically characterized to highlight specific virulence properties. Some isolated bacteria were identified as belonging to the genus Bacillus by BLAST and RDP analyses, a genus in-depth studied for plant growth-promoting ability. Moreover, 16S rRNA phylogenetic analysis showed that seven isolates grouped with Bacillus species while two and four clustered, respectively, with Neobacillus and Peribacillus. Unusually, bacterial strains belonging to Franconibacter and Stenotrophomonas were isolated from biostimulants. Although Bacillus species are generally considered nonpathogenic, most of the species have shown to swim, swarm, and produced biofilms, that can be related to bacterial virulence. The evaluation of toxins encoding genes revealed that five isolates had the potential ability to produce the enterotoxin T. In conclusion, the pathogenic potential of microorganisms included in commercial products should be deeply verified, in our opinion. The approach proposed in this study could help in this crucial step.

Effects of NAA and Ecklonia maxima Extracts on Lettuce and Tomato Transplant Production

Ecklonia maxima and the commercial biostimulants produced from it contain various plant growth regulators that are responsible for the growth stimulation recorded in many crops. Auxins are one of the major plant growth regulators contained in E. maxima extracts. The aim of this research was to evaluate the growth-promoting effect of a seaweed extract from E. maxima on lettuce and tomato transplant production under nursery conditions, and to compare the effect of this extract with an equal concentration of synthetic auxin. Two doses of natural or synthetic exogenous auxins (50 or 100 μg L−1) were supplied to the substrate through the irrigation water with an ebb and flow system, 4, 11, and 18 days after sowing. A commercial biostimulant based on E. maxima extract was used as a source of natural auxin, while 1-naphthaleneacetic acid (NAA) was used as a synthetic auxin. Seedlings supplied only with water were used as a control. Tomato seedlings treated with 100 μg L−1 of natural auxins from E. maxima extract produced the tallest plants (+22%), with a higher leaf number (+12%), a wider leaf area (+44%), and a stronger stem (+12%), whereas lettuce seedling growth was promoted by all the treatments, but with a greater effect with increasing auxin supplementation and when using E. maxima extract, compared to NAA. The results showed that the supplementation of exogenous synthetic auxin (NAA), or an E. maxima extract containing natural auxins, can have a growth-promoting effect on lettuce and tomato seedlings. This effect was more evident on lettuce than tomato. The biostimulant produced from E. maxima extracts improved seedling quality and promoted shoot and root growth more than the NAA used as a synthetic source of auxins.

Productivity of lettuce in greenhouse as affected by humic and fulvic acids application in association to mineral fertilizer

ABSTRACT Humic substances (HS) have proved to be effective in improving the productivity of vegetable crops. We examined the effect of commercial biostimulants rich in humic (HA) and fulvic acids (FA) obtained from leonardite on agronomic efficiency and nutrient content in the leaves of lettuce (Lactuca sativa). A greenhouse experiment was carried out employing 2.5-L pots containing Ultisol samples that were supplied with commercial biostimulants rich in HA and FA, alone and in combination with NPK mineral fertilizer. The application of HS biostimulants associated to mineral fertilization to the lettuce plants provided the greatest values of the studied variables, namely: plant height and diameter, leaf number per plant and root length. The combination of FA biostimulants and mineral fertilization increased the lettuce productivity relative to the inorganic fertilizer alone. The combined application of rich biostimulants FA and HA with NPK fertilizes influenced K and Fe uptake by the plants, and their accumulation in the aerial portion. Our results suggest that HS products potentialize the nutritional effect of the mineral fertilizer, when applied in combination.

Plant Material as a Novel Tool in Designing and Formulating Modern Biostimulants—Analysis of Botanical Extract from Linum usitatissimum L.

Nowadays, researchers are looking into next-generation biostimulants that can be designed as a dedicated agronomic tool based on plant materials. The aim of the present study was to develop a novel biostimulating product, based on plant material in the form of linseed aqueous extracts. The scope of the research included the physicochemical characterization of the product and identification of its biostimulating potential. The study has confirmed that the plant biostimulant derived from L. usitatissimum can be used as a viable agronomic tool for growing soybean. The designed and produced biostimulant is rich in bioactive compounds, including amino acids, free fatty acids, carbohydrates, and micro- and macroelements. The tested biostimulant showed significantly lower values of surface tension in relation to water and a commercial biostimulant. The soybean crops responded to the application of the preparation by improvements in agronomic and morphological levels. The linseed macerates were effective in terms of soybean yields and profitability. Our findings serve as preliminary evidence for the viability of designing and developing novel biostimulants derived from plant materials. This comprehensive approach to designing and formulating novel bioproducts necessitates more extensive and targeted research to fully explain the mechanisms behind the improvements observed in the soybean cultivation.

Effects of Biostimulants on the Chemical Composition of Essential Oil and Hydrosol of Lavandin (Lavandula x intermedia Emeric ex Loisel.) Cultivated in Tuscan-Emilian Apennines.

In recent years, it has been shown that biostimulants can efficiently enhance plant metabolic processes, leading to an increased production of essential oil (EO) in aromatic plants. The present study aimed to evaluate the effects of two different commercial biostimulants composed of amino acids and seaweed extract, normally used for food organic crops, on the production and composition of EO and hydrosol of Lavandula x intermedia, cultivar “Grosso”. The products were applied during 2020 growing season on lavender crops in three different locations of the Northern Italian (Emilia-Romagna Region) Apennines. Plants were harvested and EOs extracted by steam distillation and analyzed by gas chromatography. Both biostimulants affected the yield of EO per plant (+11% to +49% depending on the treatment/farm combination) without significantly changing the chemical composition of EOs and hydrosols. Conversely, the composition of EOs and hydrosols are related to the location, and the main compounds of “Grosso” cultivar, limonene, 1,8-cineole, cis-ocimene, linalool, camphor, borneol, terpinen-4-ol, and linalyl acetate, show different ratios at the experimental test sites. The differences might be due to the sunlight exposure and various maintenance of the crops over the years. In conclusion, these results suggest that the employment of biostimulants on lavandin crops do not endanger the quality of the EO while increasing biomass production and promoting the sustainability of the crop.