The Southeast Asian Journal of Tropical Biology Vol. 32 No. 3, 2025: 403 - 415 DOI: 10.11598/btb.2025.32.3.2570 ISSN: 0215-6334 | e-ISSN: 1907-770X 403 ENHANCING THERAPEUTIC SECONDARY METABOLITE PRODUCTION BY COMPREHENSIVE BIOSTIMULANT INTEGRATION: HARMONIZING PLANT AND MICROBIAL EXTRACT Anjali G.V.1 and Tamilselvi S.2* 1Department of Biotechnology, Bannari Amman Institute of Technology, Sathyamangalam 638401, Erode, Tamil Nadu, India 2Faculty of Biotechnology, Department of Biotechnology, Bannari Amman Institute of Technology, Sathyamangalam 638401, Erode, Tamil Nadu, India ARTICLE HIGLIGHTS • Integrative insights into Non- microbial and Microbial Biostimulants. • Focus on enhancing significant secondary metabolites and plant quality. • Comprehensive analysis of sustainable agricultural practices. • Future scope and positive research directions in Biostimulants. • Role of biostimulants in stress resilience. Article Information Received : 15 July 2025 Revised : 18 September 2025 Accepted : 22 October 2025 *Corresponding author, e-mail: tamilselvis@bitsathy.ac.in Review Paper ABSTRACT In recent decades, biostimulants have become recognized as organic alternatives for promoting sustainable agricultural practices, extensively applied across agriculture, horticulture, ornamental plants, and greenhouses. Unlike biofertilizers and biopesticides, biostimulants are derived from plants, animals, and microbes and classified by their chemical composition. They are primarily divided into nonmicrobial and microbial biostimulants. Nonmicrobial biostimulants include humic substances, seaweeds, chitosan, protein hydrolysates, amino acids, and inorganic compounds, while microbial biostimulants consist of plant growth-promoting bacteria and beneficial fungi. This review paper consolidates the recent positive effects of biostimulants on sustainable agriculture and outlines potential research areas for the future. Biostimulants serve as biocontrol agents that promote plant growth and development, also reported to enhance the production of valuable industrial therapeutic secondary metabolites. Traditionally, plants with medicinal properties have been used for natural remedies, and biostimulants aim to elevate the secondary metabolite content in these therapeutic plants. Additionally, the significance of both microbial and Nonmicrobial biostimulants is touched upon. A review of existing literature indicates that biostimulants significantly boost nutrient absorption, enhance resilience against abiotic stress, replenish nutrients, and improve soil quality. Keywords: biocontrol, biostimulants, microbial biostimulants, nonmicrobial biostimulants, secondary metabolites INTRODUCTION Biostimulants are substances or microorganisms that, when applied to seeds, plants, or the rhizosphere, stimulate natural processes to enhance nutrient uptake and efficiency, improve tolerance to abiotic stress, and increase crop quality and yield (Chand et al. 2024). They eventually support the growth of sustainable agricultural practices, as they are environmentally friendly and are better alternatives to synthetic fertilizers. Biostimulants or plant biostimulants are certain substances, extracts, and microbes that enhance the natural nutritional processes in plants without directly providing nutrients. They are more related to fertilizers than to most varieties of plant protection products and act in addition to fertilizing products thus reducing the nutrient application rate. Biostimulants are widely categorized as microbial and nonmicrobial biostimulants (Fig. 1). Recent European Regulation (EU 2019/1009) stated that biostimulant is a fertilizer that aims to enhance plant rhizosphere properties. The goal is not on the nutritional value of the biostimulant itself but on its capability to: a) utilize nutrient efficiency in plants; b) elevate tolerance to abiotic stress; c) improve quality; and d) absorb soil or rhizosphere nutrients (European Regulation 2019/1009). European Biostimulants Industry Council (EBIC) Copyright (c) 2025@author(s). https://doi.org/10.11598/btb.2025.32.3.2570 https://creativecommons.org/licenses/by-nc-nd/4.0/ BIOTROPIA Vol. 32 No. 3, 2025 404 Figure 1 Broad categories of biostimulants report scientific findings of biostimulants, their significance to boost plant nutrient bioavailability, and enhance plant resistance to both biotic and abiotic stress factors in various economically and therapeutically valuable crops. The comparative analysis of both natural and commercially available biostimulant effects is discussed briefly. In addition, the outline of recent regulations of the European Union (EU 2019/1009) is highlighted. REVIEW Nonmicrobial Biostimulants Humic Substances (Humic and Fulvic Acids) Humic and fulvic acids are organic compounds found in peat, soil, and other organic materials. Integration between humic and fulvic acids results in the formation of humic complexes (Mackiewicz-Walec & Olszewska 2023). Fulvic acid, an important humic substance derivative of microbial metabolism associated with minerals in soil, supports germination of seeds, encourages plant growth, promotes growth hormones, micronutrient chelation, and retains trace nutrients in the soil and make available to plants. The integrative findings from various papers offer a snapshot that contributes in gaining a recommended several fundamental principles to standardize and support the claims engineered by producers concerning PB efficiency (European Biostimulants Industry Council 2019). European Biostimulants Industry Council reported the overall benefits of using biostimulants are: a) stimulating useful compounds in plant roots; b) enhancing plant resistance to environmental abiotic stress factors (flood, drought, and extreme temperature); c) improving soil quality, health, and structure; d) elevating resource availability and decreasing nutrient loss; e) introducing beneficial microbial cultures to aid plants in uptaking and utilizing essential nutrients more effectively; f ) protecting plants against opportunistic pathogens and infections; and g) enhancing plant nutrient absorption (Mackiewicz-Walec & Olszewska 2023). Current projects on a European legal framework for plant biostimulants are being established to standardize testing procedures, branding, organizations, and quality control, with full implementation targeted for 2024 (Assi & Zahwan 2023). The current review systematically integrates the categories and importance of nonmicrobial and microbial biostimulants, focusing on sustainable agriculture practice. The critical view is to Microbial and nonmicrobial biostimulants for enhancing therapeutic metabolites - Anjali & Tamilselvi 405 comprehensive understanding of the use of humic substances. Humic acid, one of the types of plant biostimulants is often applied in the rhizosphere region for better utilization (Li et al. 2019; Ren et al. 2022). Animal matters in soil enhance the degradation and humus formation. On the other hand, humic and fulvic acids showed no significant improvement in promoting nutrient availability, growth, and resistance against stress factors, both biotic and abiotic, suggesting that these acids’ effect on plants may depend on environmental conditions and soil quality (Regelink & Koopmans 2021). The precursor for the degradation of humic acid and its complex identification is a tedious process, due to its low availability in the soil (Canellas et al. 2015). Increased crop yield and agro productivity due to the use of humic substances or humic complexes in agriculture leads to the positive effect of humic acid as biostimulants (Regelink & Koopmans 2021). By regulating the architecture of plant roots and shoots involved in nutrient intake, assimilation, and distribution, humic compounds have stimulatory effects. Additionally, humic chemicals can enhance the primary and secondary metabolic pathways linked to plant development, resistance, and abiotic stress tolerance. Humic compounds are biological activators of plant development, and their hydrophobicity, conformational elasticity, and functional group are among the chemical characteristics that substantially influence how effective they are. Numerous European projects, such as BIO-FERTIL (Poland), BIOFECTOR (Germany), and HUMIC-XL (the Netherlands), have acknowledged the potential application of growth-promoting humic compounds from waste materials (Canellas et al. 2015). Similarly, humic substances, when applied at concentration less than 0.01%, stimulated root growth and root hair elongation upright in Poa annua L. by increasing bacterial assimilation in the rhizosphere (White et al. 2021). In addition, it is reported that an increase in the assimilation of chosen nutrients supported root expansion, and strengthened drought adaptation in ryegrass cv. Speedgreen upon application of humic acid. The nutrient content of phosphorus, potassium, and zinc in leaf dry weight remains unchanged by humic acid, whereas the increase in iron content was observed (Daneshvar Hakimi Maibodi et al. 2015). Corresponding results demonstrated that the application of humic acid and biomolecules enhanced turfgrasses productivity, but showed different responses to biostimulants applied among creeping bentgrass, tall jescue, and perennial ryegrass (Acuña et al. 2022). Likewise, the effect of humic acid-containing fertilizer were evaluated on Duchesne ex-Weston Rozier grown in northern Wielkopolska, Poland, which exhibited leaves with a 60% increase in surface area, intense and dense flowering, higher yield, and more significantly thicker fruit (Zydlik & Zydlik 2023). Furthermore, the application of fulvic and humic acids to sandy and loamy soils with high and extremely low phosphorus levels, respectively, had no effect on grass yield or total nitrogen and phosphorus uptake in fertilized or unfertilized soils. Conflicts arose  that the ineffectiveness of the tested humic substances was due to the low doses compared to the soil’s existing soil organic carbon levels. Humic substances adsorb to reactive soil mineral surfaces and may not interact with plant roots as effectively as if being put in a hydroculture or soil- less substrate (Regelink & Koopmans 2021). Seaweeds Seaweeds (algae or macroalgae) are eco- friendly, nonhazardous, and eco-conscious, being widely used in sustainable and diversified farming. Seaweed extracts encourage germination as well as aid root and shoot maturation. Algae enhance phenylpropanoid pathways in plants and promote root flavonoids and microbe assimilation. Macroalgae-based biostimulant showed improved plant resistance to biotic and abiotic stresses. In 2016, the global biostimulant market was estimated to be worth approximately EUR 1.45 billion, with seaweed extract contributing to this value. Seaweed biostimulants are abundant in plant hormones, vitamins, minerals, and amino acids. Brown algae, especially Ascophyllum nodosum, when applied as organic fertilizer boost crop yield and enhance plant resistance to both biotic and abiotic stresses. Seaweed aids in photosynthetic activity and nutrient uptake with various benefits to improve grass quality during unfavorable conditions (Mackiewicz-Walec & Olszewska 2023). By incorporating perspectives from various literatures the following are formed and a detailed understanding of the differing effects of seaweeds as biostimulants is reported. BIOTROPIA Vol. 32 No. 3, 2025 406 Seaweeds are macroalgae, which main groups are classified based on the pigmentation, i.e., Chlorophyta (green), Ochrophyta (brown), and Rhodophyta (red). Ascophyllum nodosum contains about 90 groups of chemical molecules, like biologically active components, vitamins, alginic acid, and amino acids. The effects of a mixture containing Bio Algae (commercial brown seaweed derived from Ascophyllum nodosum) and mineral fertilizers on mixed stands of forage grasses resulting in an increased yield of 40% (Brouwers et al. 2018). The extraction of seaweed biostimulants includes physical (microwaves, pressure, heat) and chemical (solvents, acids, and alkalis) methods influencing the bioavailability of active compounds, determining the efficiency of biostimulants (Kapoore et al. 2021). Worldwide use of seaweed as biostimulant in agriculture has increased its need in global markets. A diverse range of biostimulants, when administered, enhance bioactive compounds in plants and regulate beneficial effects including stress resistance, root shoot elongation, increased chlorophyll content, fruit production augmentation, homogeneous fruit characteristics, senescence retardation, and elevated fruit nutritional quality (Calvo et al. 2014). Additionally, Guillard and Inguagiato (2017) reported that seaweed biostimulants had no pivotal impact on Normalized Difference Vegetation Index (NDVI) in regularly manicured turfgrasses (perennial). High-temperature parameters were not included. Hydric stress was considered and periodically monitored, indicating the effect of biostimulants depends on environmental factors. Additional studies were encouraged to determine the seaweed effect on turfgrass (Guillard & Inguagiato 2017). Chitosan Chitosan is a polysaccharide containing amino acid groups, composed of polymers of N-acetyl glucosamine and D-glucosamine linked by β-1,4 glycosidic bonds. Chitosan derived from chitin which possesses antifungal properties and aids plants to develop resistance against fungal pathogens. The following reports from existing articles provide a better understanding of chitosan. Chitin is a complex polysaccharide molecule and an abundant biopolymer in nature, followed by cellulose. Chitin is an environmentally degradable, physiologically compatible and nonhazardous molecule with multiple functional applications (Wolski et al. 2019; Goudarzian et al. 2020). Due to its potent physiological capacity, the compound chitin has gained increased attention in the last few years. Chitosan application stimulated tyrosine ammonia lyase, polyphenol oxidase, and phenylalanine enzymes, key enzymes involved in plant metabolisms, which furthermore involving antioxidant enzymes like SOD (Superoxide dismutase), catalase, and peroxidase. As biostimulant, chitosan helps plants increase productivity and showed resistance to biotic and abiotic stressors (Wang et al. 2017). Chitin derivatives play a pivotal role in various sectors. The important chitin derivatives are chitosan, N and O sulphated chitin, chitin nanoparticles, alkyl chitin, carboxymethyl chitin, dibutryl chitin, chitin nano-whiskers, chitin nanofibers, chitin nano composites, chitin oligosaccharides, and chitin hydrogels. Chitin and chitosan are reported to positively influence root growth, improve vegetative yield, and improve drought resistence in peppermint (Giglou et al. 2022). Furthermore, chitin and chitosan also regulate seed germination and suppress pathogenic fungi wide range of crops (Kanawi et al. 2021). Chitosan promotes grass growth, increases tolerance to environmental stress factors, enhances the defence system, and increased concentration of chitosan (0.1% to 0.2%) leads to leaf elongation and high maintenance. Chitosan, when used in combination with beneficial microbes, improves grass quality and benefits grass management, specifically on golf courses during autumn. Chitosan has a property of moisture sealants when applied as leaf foliar which restricts the use of water and develops resistance against stress factors. To overcome the negative impacts in agricultural practices, chitosan is used in organic farming. Chitosan forms complexes with toxic metals when applied in soils for biostimulation and botanical remediation. Chitosan regulates abscisic acid signalling pathway and activates light- dependent pathway and guards cell contraction (Hidangmayum et al. 2019). Protein Hydrolysates and Amino Acids Protein hydrolysates are major groups of plant derived organic fertilizers, consisting of amino acids and peptides or polypeptides. Protein hydrolysates are derived from plant and animal sources by chemical, thermal or enzymatic degradation (Amin et al. 2018). According to the Commission Regulation (EU) No.142/2011 Microbial and nonmicrobial biostimulants for enhancing therapeutic metabolites - Anjali & Tamilselvi 407 (Annex 1, point 14), hydrolyzed proteins such as peptides, polypeptides, amino acids, and their combinations are obtained from the degradation of animal proteins. Biomodulatory effects in protein hydrolysates is due to the presence of carbohydrates, lipids, phytohormones, minerals, phenols, and other organic substances (González-Morales et al. 2021). During adverse environmental conditions, protein hydrolysates have been shown to enhance plant adaptability principally by improving antioxidant activity in plant. Chemical traits such as optical activity of amino acids, molecular mass, electrolytic conductivity, and availability of amino acids in protein hydrolysates differ based on the chemical or enzymatic hydrolysis and origin of raw materials, like plant and animal. Protein hydrolysates promote crop growth and development making them an effective tool for organic agricultural farming. The compounds involved in protein hydrolysates metabolism are not well studied. The effect of protein hydrolysates on soil-habitat microbes in the region is not well known, thereby balancing hydrolysis parameters and enzyme materials during synthesis is critical (Canellas et al. 2015). Ugolini et al. (2023) studied the effect of protein hydrolysates extracted from oil-free seed cake of Abyssinica kale by two-step enzymatic degradation process. The study of Ugolini et al. (2023) also showed that the activity of protein hydrolysates was tested on Vigna radiate (mung bean) and Zea mays L. (maize). Furthermore, improvement in root development and architecture were reported at 4.8mM of nitrogen concentration corresponding. In addition, protein hydrolysates exhibited high nitrogen content in both root and shoot and also in chlorophyll SPAD index in maize. Most importantly the commercial biostimulant showed the same effect as shown by the natural biostimulant (Ugolini et al. 2023). The application of vegetal protein hydrolysates has gained more interest over the years. They directly stimulate nitrogen and carbon metabolism and indirectly enhance nutrient bioavailability for crop development. In addition, vegetal protein hydrolysates increase the efficient use of nitrogen. Gurav et al. (2020) reported the use of protein hydrolysates from animals in brinjal (eggplant) and chili plants, which promoted early blooming and increased yield. Accumulation of ethylene- 1-aminocyclopropane-1-carboxylate (ACC) was observed in tomato plants treated with protein hydrolysates from plant source, which also increased the shoot mass (Gurav et al. 2020). In addition, protein hydrolysates obtained from alfalfa upregulated the genes which codes for the component ferredoxin-2,LHCA5 and the enzymes involved in calvin cycle (RuBisCo) (Ertani et al. 2017). Osman et al. (2021) studied the effect of three types of protein hydrolysates on foliar application in Pisum sativum. The protein hydrolysates NAP (native whey protein), PAH (papain) or PEH (pepsin hydrolyzed whey protein) enhanced the uptake of macronutrients (N, P, and K). Collagen based protein hydrolysates when combined with FeCl₃ exhibited increased Fe content in maize plants in contrast to plants treated with FeCl₃ and FeEDTA individually. ZmTOM1 and ZmIRT 1 gene expression were improved to absorb Fe in roots (Osman et al. 2021). Our review also summarizes other beneficial effects of Nonmicrobial biostimulants on different plants with different modes of application (Table 1). Microbial Biostimulants Beneficial Bacteria Biostimulants, as alternatives to chemical inputs, include useful microbes like growth promoting bacteria and mycorrhizal fungi (Sun et al. 2023). Predominantly reviewed bacterial strains are registered subsequently. Plant growth promoting bacteria comprise both rhizobacteria that colonize the rhizosphere and free living bacteria. They play a pivotal role in solubilizing inorganic nutrients and biosynthesis of growth-promoting factors (Baltazar et al. 2021). Biofertilizers are live microbes which play a major role in promoting plant growth. On the other hand, biostimulants are substances that promote plant growth but do not meet plant nutrient demand. The major difference between biofertilizers and biostimulants are that biofertilizers meet the plant nutrients demand and increases crop quality, while biostimulants increase the quality of crop. Multitude of bacterial genus Acinetobacter, Arthobacter, Azosoirillum, Enterobacter, Ochrobactrum, Pseudomonas, and Streptomyces have a wide application in agricultural productivity to facilitate rapid crop growth, enhance nutrient absorption and utilization, minimize nutrient leaching, promote seedling establishment, enhance root growth, remediation of heavy metals- contaminated soil, enhance immune responses, BIOTROPIA Vol. 32 No. 3, 2025 408 Table 1 Categories of Nonmicrobial biostimulants and the beneficial effects Nonmicrobial biostimulant Plant Mode of application Beneficial effect Reference Humic substances Cannabis sativa L. Fertigation Observed an increase in cannabinoid content. (Bernstein et al. 2019) Zea mays L. Foliar Increased accumulation of trans-zeatin, decreased accumulation of zeatin riboside and positively altered metabolic pathways. (Gu et al. 2023) Oryza sativa Fertigation Decreased cell metabolite concentration but increased metabolic marker concentration. (Canellas et al. 2015) Festulolium braunii Soil treatment Increase in structural and Nonstructural content except lignin. (Wiśniewska- Kadzajan & Stefaniak 2020) Fulvic acid Rosmarinus officinalis L. Foliar Increased fresh and dry yield. (Farruggia et al. 2024) Pisum sativum L. var. meteor Fertigation Remarkable increase in pod number, shape, size and seed number per pod, chemical composition of seeds. (Kamran et al. 2023) Seaweeds The sugarcane varieties RB855536, SP803280, and RB855536 Foliar Increased drought resistance, crop yield, sucrose production and metabolic activities. (Jacomassi et al. 2022) Oryza sativa Foliar Increased Ca+  and K+ concentration during drought susceptible condition. Stabilized ROS production. (Banakar et al. 2022) Triticum aestivum L. var. zlata Fertigation Higher seaweed content. Increased phenolic content inhibited plant growth but showed increased content of macromolecules, pigments, and secondary metabolites. (Shibaeva et al. 2023)Cucumis sativus L. var. zozulya F1 Hyoscyamus niger Foliar Enhanced crop growth, leaves yield, and total alkaloids content. (Al-Taweel & Mohammed 2023) Ceratonia siliqua Agar treated with biostimulants Enhanced plant growth and rooting of carob. (Zouari et al. 2023) Microbial and nonmicrobial biostimulants for enhancing therapeutic metabolites - Anjali & Tamilselvi 409 Nonmicrobial biostimulant Plant Mode of application Beneficial effect Reference Chitosan Oryza sativa Foliar Act as anti-biotic stress factor ultimately increasing the chlorophyll content. (Banakar et al. 2020) Phaseolus vulgaris Foliar Increased nutrient uptake efficiency, dry weight biomass and nutrient quality. (Fawzy et al. 2023) Satureja hortensis Foliar High concentration of chitosan increased the essential oil content but there is no significant increase in carvacrol. (Alizadeh et al. 2020) Solanum lycopersicum L. Soil treatment Showed increase resistance to drought. (Jiménez-Arias et al. 2023) Agrostis stolonifera Foliar Increased shoot and root mass, elevated membrane stability under stress condition. (Li et al. 2022) Protein hydrolysates and amino acids Beta vulgaris Soil treatment Increased nutrient uptake, altered transcription rate of gene. (Jolayemi 2023) Primula acaulis cv. Soil treatment Increased biomass, chlorophyll content and surface area in plants. (Tütüncü 2024) Lactuca sativa Soil treatment Successive increase in surface area of leaf, fresh weight of leaf and root and total chlorophyll content. (Zahra et al. 2024) Ipomoea batatas L. Foliar Enhanced tuber quality and increased nutrient assimilation. (Elwaziri et al. 2023) gives aesthetic appeal to end products, and induce production of plant defence compounds(Cieślik et al. 2022; Nikolouli et al. 2021Drosophila suzukii, is an invasive pest species infesting major agricultural soft fruits. Drosophila suzukii management is currently based on insecticide applications that bear major concerns regarding their efficiency, safety and environmental sustainability. The sterile insect technique (SIT; Gorrasi et al. 2021). Enterobacter belongs to the family Enterobacteriaceae, under the class Gamma- Proteobacteria. (Nyenje et al. 2013). Enterobacter spp. are gram-negative, rod-shaped, non-spore- forming, facultative anaerobic bacteria. Enterobacter roggenkampii ED5 elicited photosynthetic respiration, plant attributes in sugarcane, and increased overall crop yield (Guo et al. 2022). Ullah et al. (2020) noted improved kernel grade, Zinc accessibility, yield, and economic viability in Kabuli chickpea by using Enterobacter spp. MN17 coating, a Zn-solubilizing endophytic bacterium. In addition, Enterobacter had considerable effects on root nodule formation in soybean and maize yield (Ullah et al. 2020). Enterobacter sichuanensis AJI 2411, found in the rhizosphere of soybean, improved plant output (Ajibade et al. 2023). Enterobacter cloacae HG-1 exhibited salinity tolerance and promoted crop development in wheat plants (Ji et al. 2020). Pseudomonas spp. entails abundant gram- negative bacterial strains, which is also the most prolific and diverse bacterial population prevalent in the natural environment (Pramanik et al. 2018). Various Pseudomonas strains express distinct environment traits involving microbial film formation, fungicidal compound synthesis, symbiotic root adhesion, cell density signaling, chemo attraction, assimilation, exudation, and metabolic dissimilation. Pseudomonas fluorescens UM270 decreased salt stress conditions in tomato plants which lead to raise in chlorophyll content, dry weight, and shoot and root extension (Rojas- Solis et al. 2023). Pseudomonas spp. RGM2987 from Philippine stevia roots exhibited improvement in indole acetic acid, solubilizing phosphate and stress relief enzyme production (Guerra et al. 2023). Kumar et al. (2021) studied the crop length and fry weight in sunflower using Pseudomonas lurida BIOTROPIA Vol. 32 No. 3, 2025 410 strain E0026 which results showed an increase in shoot and root length, increase in dry weight, and increase the Cu uptake. Pseudomonas fluorescens ECS417 controlled necrosis in leaf developed by Ralstonia solanacearum in eucalyptus (Kumar et al. 2021). Streptomyces are filamentous, gram positive, and aerobic bacteria. These bacterial strains are wide producers of secondary metabolites such as antifungals, pathogenic factors, antibiotics, and anticancer agents. Streptomycetes FJAT-31547 exhibited antimicrobial activities and increased biocontrol performance against Fusarium and bacterial rot in tomato plants, due to the presence of n-hexadecanoic acid in the Streptomycetes strain identified by GC-MS (Zheng et al. 2019. In addition, Veilumuthu et al. (2022) studied the antimicrobial activity of Streptomyces spp. VITGVIOO. Streptomyces spp. KRA18-249 exhibited biocontrol activity against various weeds. The secondary metabolite piericidin A secreted by Streptomyces spp. FXPO4 controlled fungal growth and inhibited blight damage in potato plants (Veilmuthu et al. 2022). Beneficial Fungi Microorganisms develop symbiotic relationship with plants, which aids plants in enhancing tolerance to both biotic and abiotic stresses (Żurek et al. 2022). Mycorrhizal fungi prevalent in rhizosphere improve crop growth and production. Microbes under this class are called as growth promoting fungal biostimulants (Altaey & Majid 2018). Arbuscular Mycorrhizal Fungi (AMF) improves the carbon flux in subsurface of host plants, which in turn increases the microbial population. This review reports enlighten the importance of beneficial fungi as biostimulants to promote plant yield and growth. AMF hyphae improves nutrient absorption and translocation expanding from root surface beyond mineral depletion areas, thus increasing the host plants adaptability (Rouphael et al. 2015) Competent microbial strains must exhibit prolonged beneficial effects, are easy to handle, and should not be toxic to environment and mortals (Stingl et al. 2022). Xia et al. (2021) identified the presence of bacterial (Pseudomonas veronin and Janthinobacterium lividum) and fungal (Pseudomymnoascus spp.) strains predominantly present in endobiome and root microbiome of turfgrasses. These microbes played an important role in bioconversion, nutrient uptake, and pest management (Xia et al. 2021). Giovannini et al. (2020) observed the tripartite symbiosis of AMF residing the mycorrhizosphere, plant host, and fungal symbionts. Additionally, AMF support plants fight against pathogen, enhance phosphorous solubilization, improve plant hormones production, function as iron scavengers, and promote antimicrobials synthesis (Giovannini et al. 2020). The work of Caser et al. (2019) showed that commercial formulation of Funneliforms mosseae and Rhizophagus intraradices improved flower yield in saffron, while R. intraradices alone increased active metabolites content and radial quenching activity. Schubert et al. (2020) industrially produced Micro Tom and Brioso tomatoes using Rhizoglomus irregularis and observed increase in free amino acid and carotenoid content up to fourfold when compared to control, while an increase in BRIX values were also reported. F. mosseae IMA1 and Clarideoglomus claroideum increased ROS scavenging activity and total phenol content, respectively in Romanesco artichoke (C. cardunculus L. cv. romanesco C3 Italy and Violetto Tema) (Avio et al. 2020). Other beneficial effects of microbial biostimulants on different plants with different modes of application are presented in Table 2, while beneficial plant traits enhanced by biostimulants are presented in Figure 2. Microbial and nonmicrobial biostimulants for enhancing therapeutic metabolites - Anjali & Tamilselvi 411 Table 2 C ategories of m icrobial biostim ulants and the beneficial effects M icrobial biostim ulant Plant M ode of application B eneficial effect R eference Acinetobacter calcoaceticus AC 06 and Bacillus am yloliquefaciens BA01 Arachis hypogaea L. Soil treatm ent O bserved stress resistance, osm olyte tolerance by altering stress m arker activity and physiological redox status in plants. (Sun et al. 2023) Bacillus velezensis D 2W M (D 2), Bacillus velezensis Z J-11 (Z J-11) A. roxburghii (M R H ) and A. form osanus (YYB) Fertigation Prom oted assim ilation of nutrients via roots, balancing m icrobial population in the rhizosphere. (Shahrajabian et al. 2023) Bacillus, pseudom onas and rhizobium strains Arabidopsis thaliana and Zea m ays Soil treatm ent U pregulated stress-responsive gene, im proved crop yield and quality. (D aengbussadee et al. 2021) Pseudom onas fluorescens and Burkholderia pyrrocinia Brachiaria brizantha cv. Soil treatm ent Increased photosynthetic lim itation by enhancing leaf surface area and increased biom ass production. (R an et al. 2005) Trichoderm a viride and Pseudom onas fluorescens C ucurbita pepo L. Fertigation Increased content of chlorophylls and carotenoids. Significantly elevated total phenolic profile. (Bekiesch et al. 2021) Beauveria bassiana Triticum aestivum Seed treatm ent Enhanced m icro and m acro nutrient availability, upregulated phytostim ulation in plants. (Sahaja & Pudukarapu 2019) Aureobasidium pullulans (AK 10) Abies koreana Seed treatm ent Increased tolerance to drought and enhanced m icrobial colonies. (Fu et al. 2022) BIOTROPIA Vol. 32 No. 3, 2025 412 Figure 2 Beneficial plant traits enhanced by biostimulants CONCLUSION Both nonmicrobial and microbial biostimulants function differently to enhance sustainable agriculture productivity. Humic and fulvic complexes improve root structure and chelate nutrients; seaweed extracts enriched with bioactive components boost metabolic activity and stress resilience; chitosan primes the plant defense mechanism and acts as a growth regulator; protein hydrolysates directly affect nitrogen metabolism and optimize physiological processes in plants. Simultaneously, microbial biostimulants, including Plant Growth Promoting Rhizobacteria (e.g., Bacillus, Pseudomonas, Arthrobacter, Enterobacter, and Rhizobacter) and Arbuscular Mycorrhizal Fungi (e.g., Mycorrhizal fungi and Trichoderma), improve plant efficiency by forming tripartite symbiotic relationships with plants. These biostimulants enhance nutrient availability, regulate metabolic pathways, and help plants fight pathogens by modulating root topology, photosynthesis efficiency, and secondary metabolite biosynthesis. These effects improve crop quality and resilience. Notably, the varied effects observed across crops, environmental conditions, yields, soil types, and application systems emphasize the need for systemized protocols, formulation optimization, and area- specific validation experiments. The cumulative reports highlight the effective integration of biostimulants in agriculture replacing the use of synthetic fertilizers and conservation of the agriculture land with eco-friendly substances and organisms retaining the soil health and sustainable environment. REFERENCES Acuña A, Gardner D, Villalobos L, Danneberger K. 2022. Effects of plant biostimulants on seedling root and shoot growth of three cool‐season turfgrass species in a controlled environment. Int Turfgrass Soc Res J 14(1):416-21. DOI: 10.1002/its2.97 Ajibade OA, Oladipo EK, Kwenda S, Khumalo Z, Ismail A, Oloke JK, …, Onyeaka H. 2023. Whole genomic sequence of Enterobacter sichuanensis AJI 2411 – A plant growth promoting rhizobacteria. Gene 887:147725. DOI: 10.1016/j.gene.2023.147725 Alizadeh A, Moghaddam M, Asgharzade A, Sourestani MM. 2020. Phytochemical and physiological response of Satureja hortensis L. to different irrigation regimes and chitosan application. Ind Crops Prod. 158:112990. DOI: 10.1016/j.indcrop.2020.112990 Microbial and nonmicrobial biostimulants for enhancing therapeutic metabolites - Anjali & Tamilselvi 413 Altaey DKA, Majid ZZ. 2018. The activity of antioxidants enzymes and npk contents as affected by water qaulity, kinetin, bio and organic fertilization in lettuce (Lactuca sativa L.). Iraqi J Agric Sci 49(3):506-18. DOI: 10.36103/ ijas.v49i3.123 Al-Taweel SK, Mohammed AA. 2023. Effect of exogenous application of nano fertilizers and seaweeds extract on the growth, yield, and total alkaloids content of Hyoscyamus niger. IOP Conf Ser Earth Environ Sci 1262(5). DOI: 10.1088/1755- 1315/1262/5/052010 Amin M, Ahmad R, Ali A, Hussain I, Mahmood R, Aslam M, Lee DJ. 2018. Influence of silicon fertilization on maize performance under limited water supply. Silicon 10(2):177-83. DOI: 10.1007/s12633-015-9372-x Assi NN, Zahwan TA. 2023. Response of pomegranate trees to herd manure addition and spraying with fulvic acid and brassinolide. IOP Conf Ser Earth Environ Sci 1262(4). DOI: 10.1088/1755-1315/1262/4/042071 Avio L, Maggini R, Ujvári G, Incrocci L, Giovannetti M, Turrini A. 2020. Phenolics content and antioxidant activity in the leaves of two artichoke cultivars are differentially affected by six mycorrhizal symbionts. Sci Hortic 264 (May 2019):109153. DOI: 10.1016/j.scienta.2019.109153 Baltazar M, Correia S, Guinan KJ, Sujeeth N, Bragança R, Gonçalves B. 2021. Recent advances in the molecular effects of biostimulants in plants: An overview. Biomolecules 11(8). DOI: 10.3390/biom11081096 Banakar SN, Kumar P, Gautam C, Me P. 2020. Foliar application of red seaweed (Kappaphycus alvarezii) bioformulations increased the levels of chlorophyll content in rice. J Pharmacogn Phytochem 9(1):408-10 Banakar SN, Prasanna Kumar MK, Mahesh HB, Parivallal PB, Puneeth ME, Gautam C, …, Narayan SS. 2022. Red- seaweed biostimulants differentially alleviate the impact of fungicidal stress in rice (Oryza sativa L.). Sci Rep 12(1):1- 12. DOI: 10.1038/s41598-022-10010-8 Bekiesch P, Oberhofer M, Sykora C, Urban E, Zotchev SB. 2021. Piperazic acid containing peptides produced by an endophytic Streptomyces sp. isolated from the medicinal plant Atropa belladonna. Nat Prod Res 35(7):1090-96. DOI: 10.1080/14786419.2019. 1639174 Bernstein N, Gorelick J, Zerahia R, Koch S. 2019. Impact of N, P, K, and humic acid supplementation on the chemical profile of medical cannabis (Cannabis sativa L). Front Plant Sci 10. DOI: 10.3389/fpls.2019.00736 Brouwers E, Draisma M, Swam K van, Veen AJ, Burger L. 2018. Identification of the seaweed b i o s t i m u l a n t market (phase 1). (Phase 1):1-64. Available from: https:// www. northseafarmers.org/public/documents/Bio4safe_ WP1_D112_Seaweed-biostimulant- market_North-Sea- Farm-Foundation_December-2018.pdf Calvo P, Nelson L, Kloepper JW. 2014. Agricultural uses of plant biostimulants. Plant Soil 383(1-2):3-41. DOI: 10.1007/s11104-014-2131-8 Canellas LP, Olivares FL, Aguiar NO, Jones DL, Nebbioso A, Mazzei P, Piccolo A. 2015. Humic and fulvic acids as biostimulants in horticulture. Sci Hortic 196:15-27. DOI: 10.1016/j.scienta.2015.09.013 Caser M, Victorino ÍMM, Demasi S, Berruti A, Donno D, Lumini E,…, Scariot V. 2019. Saffron cultivation in marginal alpine environments: How AMF inoculation modulates yield and bioactive compounds. Agronomy 9(1). DOI: 10.3390/agronomy9010012 Chand D, Pratap M, Birthal S, Kumara TMK. 2024. Biostimulants for sustainable development of agriculture: A bibliometric content analysis. Discov Agric (2025). DOI: 10.1007/s44279-024-00149-5 Cieślik M, Harhala M, Orwat F, Dąbrowska K, Górski A, Jończyk-Matysiak E. 2022. Two newly isolated enterobacter-specific bacteriophages: Biological properties and stability studies. Viruses 14(7). DOI: 10.3390/ v14071518 Daengbussadee C, Laopaiboon L, Kaewmaneewat A, Sirisantimethakom L, Laopaiboon P. 2021. Novel methods using an Arthrobacter sp. to create anaerobic conditions for biobutanol production from sweet sorghum juice by Clostridium beijerinckii. Processes 9(1):1-11. DOI: 10.3390/pr9010178 Daneshvar Hakimi Maibodi N, Kafi M, Nikbakht A, Rejali F. 2015. Effect of foliar applications of humic acid on growth, visual quality, nutrients content and root parameters of perennial ryegrass (Lolium perenne L.). J Plant Nutr 38(2):224-36. DOI: 10.1080/01904167.2014.939759 Elwaziri E, Ismail H, El-Khairl ESA, Al-Qahtani SM, Al-Harbi NA, Abd Elgawad HG, …, Osman A. 2023. Biostimulant application of whey protein hydrolysates and potassium fertilization enhances the productivity and tuber quality of sweet potato. Not Bot Horti Agrobot Cluj-Napoca 51(2):1-16. DOI: 10.15835/nbha51213122 Ertani A, Schiavon M, Nardi S. 2017. Transcriptome- wide identification of differentially expressed genes in Solanum lycopersicon L. in response to an Alfalfa-protein hydrolysate using microarrays. Front Plant Sci 8:1–19. DOI: 10.3389/fpls.2017.01159 Farruggia D, Tortorici N, Iacuzzi N, Alaimo F, Leto C, Tuttolomondo T. 2024. Biostimulants improve plant performance of rosemary growth in agricultural organic system. Agronomy 14(1). DOI: 10.3390/ agronomy14010158 Fawzy ZF, El-Ramady H, Azab MA, Mahdy HAA. 2023. Can foliar application of natural biostimulants reduce nitrate and fiber content in fresh green bean under soil nutrient deficiency? Bull Natl Res Cent. 47(1). DOI: 10.1186/ s42269-023-01135-5 Gao P, Wang K, Qi C, Chen K, Xiang W, Zhang Y, …, Shu C. 2024. A new method for discovering plant biostimulants. Plants 13(1). DOI: 10.3390/plants13010056 Giglou MT, Giglou RH, Esmaeilpour B, Azarmi R, Padash A, Falakian M, …, Lajayer HM. 2022. A new method in mitigation of drought stress by chitosan-coated iron oxide nanoparticles and growth stimulant in peppermint. Ind Crops Prod 187. DOI: 10.1016/j.indcrop.2022.115286 Giovannini L, Palla M, Agnolucci M, Avio L, Sbrana C, Turrini A, Giovannetti M. 2020. Arbuscular mycorrhizal fungi and associated microbiota as plant biostimulants: Research strategies for the selection of the best performing inocula. Agronomy 10(1). DOI: 10.3390/agronomy10010108 BIOTROPIA Vol. 32 No. 3, 2025 414 González-Morales S, Solís-Gaona S, Valdés-Caballero MV, Juárez-Maldonado A, Loredo-Treviño A, Benavides- Mendoza A. 2021. Transcriptomics of biostimulation of plants under abiotic stress. Front Genet 12. DOI: 10.3389/ fgene.2021.583888 Gorrasi S, Pasqualetti M, Franzetti A, Gonzalez-Martinez A, Gonzalez-Lopez J, Muñoz- Palazon B, Fenice M. 2021. Persistence of enterobacteriaceae drawn into a marine saltern (Saline di Tarquinia, Italy) from the adjacent coastal zone. Water 13(11):1-15. DOI: 10.3390/w13111443 Goudarzian A, Pirbalouti AG, Hossaynzadeh M. 2020. Menthol, balance of menthol/menthone, and essential oil contents of Mentha × Piperita L. under foliar-applied chitosan and inoculation of Arbuscular Mycorrhizal Fungi. J Essent Oil-Bearing Plants 23(5):1012-21. DOI: 10.1080/0972060X.2020.1828177 Guerra M, Carrasco-Fernández J, Valdés JH, Panichini M, Castro JF. 2023. Draft genome of Pseudomonas sp. RGM 2987 isolated from Stevia philippiana roots reveals its potential as a plant biostimulant and potentially constitutes a novel species. Electron J Biotechnol 61:9-13. DOI: 10.1016/j.ejbt.2022.10.001 Guillard K, Inguagiato JC. 2017. Normalized difference vegetative index response of nonirrigated Kentucky bluegrass and tall fescue lawn turf receiving seaweed extracts. Hort Science 52(11):1615-20. DOI: 10.21273/ HORTSCI12090-17 Guo DJ, Li DP, Singh RK, Singh P, Verma KK, Sharma A, ,…, Li YR. 2022. Comparative transcriptome analysis of two sugarcane varieties in response to diazotrophic plant growth promoting endophyte Enterobacter roggenkampii ED5. J Plant Interact 17(1):75-84. DOI: 10.1080/17429145.2021.2012608 Gurav R, Nalavade V, Aware C, Vyavahare G, Bhatia SK, Yang YH, …, Jadhav J. 2020. Microbial degradation of poultry feather biomass in a constructed bioreactor and application of hydrolysate as bioenhancer to vegetable crops. Environ Sci Pollut Res 27(2):2027-35. DOI: 10.1007/s11356-019-06536-6 Gu YL, Li JZ, Li Y, Cong S, Wang J, Ma YN, Wei HL. 2023. Pseudomonas cyclic lipopeptide medpeptin: Biosynthesis and modulation of plant immunity. Engineering 28:153- 65. DOI: 10.1016/j.eng.2023.05.016 Hidangmayum A, Dwivedi P, Katiyar D, Hemantaranjan A. 2019. Application of chitosan on plant responses with special reference to abiotic stress. Physiol Mol Biol Plants 25(2):313-26. DOI: 10.1007/s12298-018-0633-1 Jacomassi LM, Viveiros J de O, Oliveira MP, Momesso L, de Siqueira GF, Crusciol CAC. 2022. A seaweed extract-based biostimulant mitigates drought stress in sugarcane. Front Plant Sci 13. DOI: 10.3389/fpls.2022.865291 Ji C, Liu Z, Hao L, Song X, Wang C, Liu Y, …, Liu X. 2020. Effects of Enterobacter cloacae HG-1 on the nitrogen- fixing community structure of wheat rhizosphere Soil and on Salt Tolerance. Front Plant Sci 11:1-17. DOI: 10.3389/ fpls.2020.01094 Jiménez-Arias D, Morales-Sierra S, Suárez E, Lozano- Juste J, Coego A, Estevez JC, …, Rodriguez PL. 2023. Abscisic acid mimic-fluorine derivative 4 alleviates water deficit stress by regulating ABA-responsive genes, proline accumulation, CO2 assimilation, water use efficiency and better nutrient uptake in tomato plants. Front Plant Sci 14:1-12. DOI: 10.3389/fpls.2023.1191967 Jolayemi OL. 2023. Biostimulant potential of agro-industrial side-streams-sustainable sugar beet cultivation and drought tolerance in wheat. Acta Univ Agric Suec 2023:71. DOI: 10.54612/a.42nikatmm3 Kamran A, Mushtaq M, Arif M, Rashid S. 2023. Role of biostimulants (ascorbic acid and fulvic acid) to synergize Rhizobium activity in pea (Pisum sativum L. var. meteor). Plant Physiol Biochem 196:668-82. DOI: 10.1016/j. plaphy.2023.02.018 Kanawi MA, Haydar MAL, Radhi WN. 2021. Effect of chitin and chitosan in improvement of plant growth and anti- fungal activity. Egypt J Bot 61(2):513-19. DOI: 10.21608/ejbo.2021.41084.1549 Kapoore RV, Wood EE, Llewellyn CA. 2021. Algae biostimulants: A critical look at microalgal biostimulants for sustainable agricultural practices. Biotechnol Adv 49:107754. DOI: 10.1016/j.biotechadv.2021.107754 Kumar A, Tripti, Voropaeva O, Maleva M, Panikovskaya K, Borisova G, …, Bruno LB. 2021. Bioaugmentation with copper tolerant endophyte Pseudomonas lurida strain EOO26 for improved plant growth and copper phytoremediation by Helianthus annuus. Chemosphere 266. DOI: 10.1016/j.chemosphere.2020.128983 Li Q, Li R, He F, Yang Z, Yu J. 2022. Growth and physiological effects of chitosan on heat tolerance in creeping bentgrass (Agrostis stolonifera). Grass Res 2. DOI: 10.48130/GR- 2022-0006 Li Y, Fang F, Wei J, Wu X, Cui R, Li G, …, Tan D. 2019. Humic acid fertilizer improved soil properties and soil microbial diversity of continuous cropping peanut: A Three-Year Experiment. Sci Rep 9(1):1-9. DOI: 10.1038/ s41598-019-48620-4 Mackiewicz-Walec E, Olszewska M. 2023. Biostimulants in the Production of Forage Grasses and Turfgrasses. Agric. 13(9). DOI: 10.3390/agriculture13091796 Nikolouli K, Sassù F, Ntougias S, Stauffer C, Cáceres C, Bourtzis K. 2021. Enterobacter sp. Aa26 as a protein source in the larval diet of drosophila suzukii. Insects 12(10):1- 16. DOI: 10.3390/insects12100923 Nyenje ME, Green E, Ndip RN. 2013. Evaluation of the effect of different growth media and temperature on the suitability of biofilm formation by Enterobacter cloacae strains isolated from food samples in South Africa. Molecules 18(8):9582-93. DOI: 10.3390/molecules18089582 Osman A, Merwad ARM, Mohamed AH, Sitohy M. 2021. Foliar spray with pepsin-and papain- w h e y protein hydrolysates promotes the productivity of pea plants cultivated in clay loam soil. Molecules 26(9). DOI: 10.3390/molecules26092805 Pramanik K, Mitra S, Sarkar A, Maiti TK. 2018. Alleviation of phytotoxic effects of cadmium on rice seedlings by cadmium resistant PGPR strain Enterobacter aerogenes MCC 3092. J Hazard Mater 351:317-29. DOI: 10.1016/j.jhazmat.2018.03.009 Microbial and nonmicrobial biostimulants for enhancing therapeutic metabolites - Anjali & Tamilselvi 415 Regelink IC, Koopmans GF. 2021. Effects of biostimulants and fertilization on nutrient uptake by grass and composition of soil pore water versus 0.01 M CaCl2 soil extracts. Commun Soil Sci Plant Anal 52(20):2516-32. DOI: 10.1080/00103624. 2021.1953051 Ren H, Islam MS, Wang H, Guo H, Wang Z, Qi X, …, Li B. 2022. Effect of humic acid on soil physical and chemical properties, microbial community structure, and metabolites of decline diseased bayberry. Int J Mol Sci 23(23):1-22. DOI: 10.3390/ijms232314707 Rojas-Solis D, Vences-Guzmán MÁ, Sohlenkamp C, Santoyo G. 2023. Cardiolipin synthesis in Pseudomonas fluorescens UM270 plays a relevant role in stimulating plant growth under salt stress. Microbiol Res 268. DOI: 10.1016/j. micres.2022.127295 Rouphael Y, Franken P, Schneider C, Schwarz D, Giovannetti M, Agnolucci M, …, Colla G. 2015. Arbuscular mycorrhizal fungi act as biostimulants in horticultural crops. Sci Hortic 196(081):91-108. DOI: 10.1016/j.scienta.2015.09.002 Sahaja K, Pudukarapu L. 2019. Preprint not peer rev Preprin tnot peer ved. 6(6):1-4. Schubert R, Werner S, Cirka H, Rödel P, Moya YT, Mock HP, …, Hause B. 2020. Effects of arbuscular mycorrhization on fruit quality in industrialized tomato production. Int J Mol Sci 21(19):1-15. DOI: 10.3390/ijms21197029 Shahrajabian MH, Petropoulos SA, Sun W. 2023. Survey of the influences of microbial biostimulants on horticultural crops: Case studies and successful paradigms. Horticulturae 9(2):1-24. DOI: 10.3390/horticulturae9020193 Shibaeva T, Sherudilo E, Bogolitsyn K, Parshina A, Mamatmurodov K. 2023. Plant growth promoting properties of four arctic seaweed extracts. BIO Web Conf 57. DOI: 10.1051/bioconf/20235706005 Stingl U, Choi CJ, Dhillon B, Schiavon M. 2022. The lack of knowledge on the microbiome of golf turfgrasses impedes the development of successful microbial products. Agronomy 12(1):1-13. DOI: 10.3390/ agronomy12010071 Sun W, Shahrajabian MH, Petropoulos SA, Shahrajabian N. 2023. Developing sustainable agriculture systems in medicinal and aromatic plant production by using chitosan and chitin-based biostimulants. Plants12(13). DOI: 10.3390/plants12132469 Tütüncü M. 2024. Effects of protein hydrolysate derived from anchovy by-product on plant growth of primrose and root system architecture analysis with machine learning. Horticulturae 10(4). DOI: 10.3390/ horticulturae10040400 Ugolini L, Malaguti L, Matteo R, Pagnotta E, Beleggia R, Righetti L. 2023. Protein hydrolysates from Crambe abyssinica seed cake as potential biostimulants for root development. Agronomy 13(11):1-19. DOI: 10.3390/ agronomy13112755 Ullah A, Farooq M, Hussain M. 2020. Improving the productivity, profitability and grain quality of kabuli chickpea with co-application of zinc and endophyte bacteria Enterobacter sp. MN17. Arch Agron Soil Sci 66(7):897-912. DOI: 10.1080/03650340.2019.1644501 Veilumuthu P, Nagarajan T, Sasikumar S, Siva R, Jose S, Christopher JG. 2022. Streptomyces sp. VITGV100: An endophyte from Lycopersicon esculentum as new source of indole type compounds. Biochem Syst Ecol 105:104523. DOI: 10.1016/j.bse.2022.104523 Wang M, Gao L, Dong S, Sun Y, Shen Q, Guo S. 2017. Role of silicon on plant–pathogen interactions. Front Plant Sci 8:1-14. DOI: 10.3389/fpls.2017.00701 White JF, Chang X, Kingsley KL, Zhang Q, Chiaranunt P, Micci A, …, Kowalski KP. 2021. Endophytic bacteria in grass crop growth promotion and biostimulation. Grass Res 1: 1-9. DOI: 10.48130/GR-2021-0005 Wiśniewska-Kadzajan B, Stefaniak G. 2020. Effects of slurry applied with soil conditioners and mineral fertilizers on fiber fraction content in Festulolium braunii (K. Richt.) A. Camus. Appl Sci 10(18):1573-83. DOI: 10.3390/ APP10186554 Wolski K, Biernacik M, Świerszcz S, Talar-Krasa M, Leshchenko O. 2019. Effect of the application of a biostimulant and mineral fertilizers on the concentration of mineral elements in the sward of forage mixtures cultivated on light soil. J Elem 24(1):385-97. D O I : 10.5601/jelem.2018.23.2.1569 Xia Q, Rufty T, Shi W. 2021. Predominant microbial colonizers in the root endosphere and rhizosphere of turfgrass systems: Pseudomonas veronii, Janthinobacterium lividum, and Pseudogymnoascus spp. Front Microbiol 12:1-13. DOI: 10.3389/fmicb.2021. 643904 Zahra AM, Sinaga ANK, Nugroho BDA, Masithoh RE. 2024. Effect of plant biostimulants on red and green romaine lettuce (Lactuca sativa) growth in indoor farming. IOP Conf Ser Earth Environ Sci 1297(1). DOI: 10.1088/1755- 1315/1297/1/012008 Zheng X, Wang J, Chen Z, Zhang H, Wang Z, Zhu Y, Liu B. 2019. A Streptomyces sp. strain: Isolation, identification, and potential as a biocontrol agent against soilborne diseases of tomato plants. Biol Control 136:104004. DOI: 10.1016/j.biocontrol.2019.104004 Zouari N, Bougdaoua H, El Mtili N. 2023. Effect of liquid seaweed (Ulva rigida) extract on the growth and rooting of carob (Ceratonia siliqua L.). J Appl Biol Biotechnol 11(1):55-60. DOI: 10.7324/JABB.2023.110107 Żurek G, Wiewióra B, Rybka K, Prokopiuk K. 2022. Different response of perennial ryegrass—Epichloë endophyte symbiota to the elevated concentration of heavy metals in soil. J Appl Genet 63(1):47-59. DOI: 10.1007/s13353- 021-00661-0 Zydlik Z, Zydlik P. 2023. The effect of a preparation containing humic acids on the growth, yield, and quality of strawberry fruits (Fragaria × ananassa (Duchesne ex Weston) Duchesne ex Rozier). Agronomy 13(7). DOI: 10.3390/ agronomy13071872