Plant Biostimulants: Exploring Sustainable Sources and their Applications in Agriculture Production

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Phytochemistry".

Deadline for manuscript submissions: closed (31 July 2024) | Viewed by 11639

Special Issue Editor


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Guest Editor
Research Centre for Plant Growth and Development, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg 3201, South Africa
Interests: microalgae cultivation; phytohormones; biostimulants; bioactive compounds from algae

Special Issue Information

Dear Colleagues,

Intensive agricultural practices use synthetic agrochemicals to maximize crop yields and protect plants against abiotic and biotic stresses. Their long-term use can lead to environmental problems such as soil salinization and the eutrophication of water systems. It is also harmful to beneficial soil microbial communities. Efforts are underway to develop more environmentally friendly natural biostimulants with lower environmental impacts to replace these synthetic agrochemicals.

Sources of plant biostimulants include a variety of organic and inorganic substances, natural compounds, and/or beneficial microorganisms such as algae and plant extracts, humic acids, protein hydrolysates, and endophytic fungi. Applying plant biostimulants is an effective strategy to enhance sustainable development practices. The effects of plant biostimulants include increasing the efficiency of plant uptake and utilizing nutrients, tolerance to abiotic stresses, and ultimately improving the quality of agricultural products.

This Special Issue welcomes articles (original research articles and reviews) that explore the sources of plant biostimulants; elaborate on different sources of plant biostimulants to optimize crop growth under stressful environments (including drought, nutrient deficiencies, heavy metal contamination, toxicity, and flooding); and application of plant biostimulants in nutrient efficiency, sustainable agricultural production, and regulation of microbial population quantity and quality.

Dr. Wendy Ann Stirk
Guest Editor

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Keywords

  • mass culture optimization
  • extract formulation and standardization
  • active compounds
  • modes of action
  • physiological responses
  • plant protection
  • biocontrol agents
  • synergism with other biostimulants
  • seed priming
  • post-harvest storage

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Published Papers (7 papers)

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Research

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15 pages, 2157 KiB  
Article
Effects of Biostimulants on the Eco-Physiological Traits and Fruit Quality of Black Chokeberry (Aronia melanocarpa L.)
by Anastasia Giannakoula, Georgia Ouzounidou, Stefanos Stefanou, George Daskas and Olga Dichala
Plants 2024, 13(21), 3014; https://doi.org/10.3390/plants13213014 - 28 Oct 2024
Viewed by 563
Abstract
Biostimulants contribute to the physiological growth of plants by enhancing the quality characteristics of fruit without harming the environment. In addition, biostimulants applied to plants strengthen nutritional efficiency, abiotic stress tolerance, and fruit biochemical traits. We investigated the effectiveness of specific organic biostimulants. [...] Read more.
Biostimulants contribute to the physiological growth of plants by enhancing the quality characteristics of fruit without harming the environment. In addition, biostimulants applied to plants strengthen nutritional efficiency, abiotic stress tolerance, and fruit biochemical traits. We investigated the effectiveness of specific organic biostimulants. Five treatments were tested: (1) control (H2O, no biostimulants); (2) Magnablue + Keyplex 350 (Mgl + Kpl350); (3) Cropobiolife + Keyplex 120 (Cpl + Kpl120); (4) Keyplex 120 (Kpl120); and (5) Magnablue + Cropobiolife + Keyplex 120 (Mgl + Cpl + Kpl120) on the mineral uptake and physiology in black chokeberry (Aronia) plants, as well as the quality of their berries. The different treatments were applied to three-year-old chokeberry plants, and the experimental process in the field lasted from May to September 2022 until the harvest of ripe fruits. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) revealed that the fifth treatment significantly increased concentrations of P, Ca, and K. Additionally, the fifth treatment enhanced photochemical efficiency (Fv/Fm), water-splitting efficiency (Fv/Fo) in PSII, and the performance index (PI) of both PSI and PSII in chokeberry leaves. Improvements in photosynthesis, such as CO2 assimilation (A), transpiration (E), and water-use efficiency (A/E), were also noted under biostimulant applications. Upon harvesting the ripe fruits, part of them was placed at room temperature at 25 °C, while the rest were stored at 4 °C, RH 90% for 7 days. The cultivation with biostimulants had beneficial effects on the maintenance of flesh consistency, ascorbic acid concentration, and weight of berries at 4 and 25 °C, especially in the 5th treatment. Moreover, the total antioxidant capacity, anthocyanin concentration, and total phenols of the berries were notably higher in the third and fifth treatments compared to the control. These data suggest that selecting appropriate biostimulants can enhance plant yield and fruit quality by potentially activating secondary metabolite pathways. Full article
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14 pages, 2174 KiB  
Article
Metabolome Shift in Centella asiatica Leaves Induced by the Novel Plant Growth-Promoting Rhizobacterium, Priestia megaterium HyangYak-01
by Min-Chul Kim, HyungWoo Jo, Kyeongmo Lim, Ikwhan Kim, Hye-Been Kim, Sol Kim, Younhwa Nho, Misun Kim, Hyeyoun Kim, Chaeyun Baek, Young Mok Heo, Haeun Lee, Seunghyun Kang, Dong-Geol Lee, Kyudong Han and Jae-Ho Shin
Plants 2024, 13(18), 2636; https://doi.org/10.3390/plants13182636 - 21 Sep 2024
Viewed by 833
Abstract
Centella asiatica, a traditional herb, is widely recognized for its pharmacologically active components, such as asiaticoside, madecassoside, asiatic acid, and madecassic acid. These components render it a highly sought-after ingredient in various industries, including cosmetics and pharmaceuticals. This study aimed to enhance [...] Read more.
Centella asiatica, a traditional herb, is widely recognized for its pharmacologically active components, such as asiaticoside, madecassoside, asiatic acid, and madecassic acid. These components render it a highly sought-after ingredient in various industries, including cosmetics and pharmaceuticals. This study aimed to enhance the production and activity of these pharmacological constituents of C. asiatica using the plant growth-promoting rhizobacterium Priestia megaterium HyangYak-01 during its cultivation. To achieve this goal, the researchers conducted field experiments, which revealed an increase in the production of pharmacologically active compounds in C. asiatica cultivated with a P. megaterium HyangYak-01 culture solution. Additionally, quadrupole time-of-flight mass spectrometry (Q-TOF MS) confirmed that the composition ratios of the C. asiatica extract treated with the P. megaterium HyangYak-01 culture solution differed from those of the untreated control and type strain-treated groups. Skin cell experiments indicated that the C. asiatica extract treated with the P. megaterium HyangYak-01 culture solution exhibited greater skin barrier improvement and less pronounced inflammatory responses than those from plants grown without the bacterial culture solution. This study demonstrates that microbial treatment during plant cultivation can beneficially influence the production of pharmacological constituents, suggesting a valuable approach toward enhancing the therapeutic properties of plants. Full article
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16 pages, 6758 KiB  
Article
Revealing the Complex Interplay of Biostimulant Applications
by Ye Yuan and Nicholas Dickinson
Plants 2024, 13(16), 2188; https://doi.org/10.3390/plants13162188 - 8 Aug 2024
Viewed by 1065
Abstract
Some biostimulant products provide proven benefits to plant production, potentially offering more environmentally friendly, sustainable, and natural inputs into production systems. However, the transference and predictability of known benefits between different growth environments, application protocols, and management systems are fraught with difficulty. In [...] Read more.
Some biostimulant products provide proven benefits to plant production, potentially offering more environmentally friendly, sustainable, and natural inputs into production systems. However, the transference and predictability of known benefits between different growth environments, application protocols, and management systems are fraught with difficulty. In this study, we carried out carefully controlled glasshouse and in vitro assays with applications of humic acids, protein hydrolysates, and seaweed extract to compare the variability of biostimulant effects and dosage-dependent variations across diverse conditions, encompassing a sufficient range to comprehensively assess their full spectrum of impacts. The results demonstrated a clear trend of dosage-dependent effects with each biostimulant exhibiting a significant growth-promoting effect within a critical concentration range, but detrimental effects when the concentration fell outside this range. While substantial growth-promoting effects were observed under glasshouse conditions, biostimulant applications tended to be more sensitive and generally led to negative impacts in sterilised conditions. The combined use of biostimulants mostly resulted in detrimental and toxicological responses with only two combined treatments showing marginal synergistic effects. The findings demonstrated a complex interplay between biostimulants and the growth conditions of plants. Lack of knowledge of the indirect effects of different growth media may result in negative impacts of biostimulant applications and combinations of products outside narrow critical concentration ranges. Full article
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16 pages, 452 KiB  
Article
Enriching NPK Mineral Fertilizer with Plant-Stimulating Peptides Increases Soilless Tomato Production, Grower Profit, and Environmental Sustainability
by Michele Ciriello, Sara Rajabi Hamedani, Youssef Rouphael, Giuseppe Colla and Mariateresa Cardarelli
Plants 2024, 13(14), 2004; https://doi.org/10.3390/plants13142004 - 22 Jul 2024
Viewed by 888
Abstract
The need to increase agricultural production to feed a steadily growing population may clash with the more environmentally friendly but less efficient production methods required. Therefore, it is important to try to reduce the use of chemical inputs without compromising production. In this [...] Read more.
The need to increase agricultural production to feed a steadily growing population may clash with the more environmentally friendly but less efficient production methods required. Therefore, it is important to try to reduce the use of chemical inputs without compromising production. In this scenario, natural biostimulants have become one of the most sought-after and researched technologies. In the present study, the results of a greenhouse experiment on hydroponic tomatoes (Solanum lycopersicum L.) are presented, which involved comparing the use of ordinary NPK fertilizer (Cerbero®) with the use of NPK fertilizers enriched with 0.5% protein hydrolysate of plant origin (Cerbero Green®) at both standard (100%) and reduced (70%) fertilization rates. The results highlight how the use of Cerbero Green® fertilizers improves the production performance of tomatoes. More specifically, they show that the use of Cerbero Green® leads to higher marketable yields, especially under reducing fertilizer use, ensuring a positive net change in profit for the grower. In addition, carbon footprint analysis has revealed that the use of Cerbero Green® reduces the environmental impact of hydroponic tomato growing practices by up to 8%. The observed higher yield of hydroponically grown tomatoes even with reduced fertilization rates underlines once again the key role of natural biostimulants in increasing both the economic and environmental sustainability of horticultural production. Full article
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17 pages, 1944 KiB  
Article
An Evaluation of the Effectivity of the Green Leaves Biostimulant on Lettuce Growth, Nutritional Quality, and Mineral Element Efficiencies under Optimal Growth Conditions
by Santiago Atero-Calvo, María José Izquierdo-Ramos, Carmen García-Huertas, Miguel Rodríguez-Alcántara, Iván Navarro-Morillo and Eloy Navarro-León
Plants 2024, 13(7), 917; https://doi.org/10.3390/plants13070917 - 22 Mar 2024
Viewed by 1279
Abstract
The use of biostimulants is becoming a useful tool for increasing crop productivity while enhancing nutritional quality. However, new studies are necessary to confirm that the joint application of different types of biostimulants, together with bioactive compounds, is effective and not harmful to [...] Read more.
The use of biostimulants is becoming a useful tool for increasing crop productivity while enhancing nutritional quality. However, new studies are necessary to confirm that the joint application of different types of biostimulants, together with bioactive compounds, is effective and not harmful to plants. This study examined the impact of applying the biostimulant Green Leaves, comprising Macrocystis algae extract and containing a mixture of amino acids, corn steep liquor extract, calcium, and the bioactive compound glycine betaine. The effect of applying two different doses (3 and 5 mL L−1) of this biostimulant was evaluated on lettuce plants, and growth and quality parameters were analyzed along with photosynthetic efficiency, nutritional status, and nutrient efficiency parameters. The application of Green Leaves improved plant weight (25%) and leaf area and enhanced the photosynthetic rate, the accumulation of soluble sugars and proteins, and the agronomic efficiency of all essential nutrients. The 3 mL L−1 dose improved the nutritional quality of lettuce plants, improving the concentration of phenolic compounds and ascorbate and the antioxidant capacity and reducing NO3 accumulation. The 5 mL L−1 dose improved the absorption of most nutrients, especially N, which reduced the need for fertilizers, thus reducing costs and environmental impact. In short, the Green Leaves product has been identified as a useful product for obtaining higher yield and better quality. Full article
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11 pages, 278 KiB  
Article
Assessment of the Effect of Treating ‘GiSelA 5’ Softwood Cuttings with Biostimulants and Synthetic Auxin on Their Root Formation and Some of Their Physiological Parameters
by Sławomir Świerczyński
Plants 2023, 12(3), 658; https://doi.org/10.3390/plants12030658 - 2 Feb 2023
Cited by 1 | Viewed by 1355
Abstract
The ‘GiSelA 5’ rootstock is of high importance for growing sweet cherries because it significantly reduces the growth vigour of the trees and accelerates their fruiting. However, the method of its propagation using ‘in vitro’ cultures is expensive, prompting researchers to look for [...] Read more.
The ‘GiSelA 5’ rootstock is of high importance for growing sweet cherries because it significantly reduces the growth vigour of the trees and accelerates their fruiting. However, the method of its propagation using ‘in vitro’ cultures is expensive, prompting researchers to look for alternative methods of propagation. One of these is the root formation in shoot cuttings. The experiment presented in this paper compared the use of powdered synthetic auxins (Rhizopon AA, Ukorzeniacz AB) and their alcoholic solution (IAA, IBA), and the biostimulants Goteo and Bispeed as foliar sprays for root formation in softwood cuttings ‘GiSelA 5’ and measured some parameters of physiological processes. In addition, two different substrates of river sand with peat (1:2) and peat substrate with perlite (2:1) were used. Cuttings were obtained on two dates, in the first and third years in the month of June. Biostimulants increased the number of rooted cuttings (Goteo—16.1%, Bispeed—18.1%) without improving their growth and the intensity of most of the analyzed physiological processes compared to the control. Synthetic preparations also increased the percentage of rooted cuttings Rhizopon AA (24.4%), Ukorzeniacz AB (21.4%), auxin IBA (19.7%) and auxin IAA (14.7%), while simultaneously improving their growth and level of vital processes compared to the controls and biostimulants. The substrate consisting of peat with sand improved root formation by 6.2%, without significantly changing the growth parameters and vital functions of the cuttings. The earlier date of propagation increased the root formation percentage only by 4% and the number of roots by 14% of the ‘GiSelA 5’ rootstock cuttings. Full article

Review

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26 pages, 1317 KiB  
Review
A Comprehensive Review of Microalgae and Cyanobacteria-Based Biostimulants for Agriculture Uses
by Amer Chabili, Farah Minaoui, Zineb Hakkoum, Mountasser Douma, Abdelilah Meddich and Mohammed Loudiki
Plants 2024, 13(2), 159; https://doi.org/10.3390/plants13020159 - 6 Jan 2024
Cited by 9 | Viewed by 4670
Abstract
Significant progress has been achieved in the use of biostimulants in sustainable agricultural practices. These new products can improve plant growth, nutrient uptake, crop yield and quality, stress adaptation and soil fertility, while reducing agriculture’s environmental footprint. Although it is an emerging market, [...] Read more.
Significant progress has been achieved in the use of biostimulants in sustainable agricultural practices. These new products can improve plant growth, nutrient uptake, crop yield and quality, stress adaptation and soil fertility, while reducing agriculture’s environmental footprint. Although it is an emerging market, the biostimulant sector is very promising, hence the increasing attention of the scientific community and agro-industry stakeholders in finding new sources of plant biostimulants. Recently, pro- and eucaryotic microalgae have gained prominence and can be exploited as biostimulants due to their ability to produce high-value-added metabolites. Several works revealed the potential of microalgae- and cyanobacteria-based biostimulants (MCBs) as plant growth promoters and stress alleviators, as well as encouraging results pointing out that their use can address current and future agricultural challenges. In contrast to macroalgae biostimulants, the targeted applications of MBs in agriculture are still in their earlier stages and their commercial implementation is constrained by the lack of research and cost of production. The purpose of this paper is to provide a comprehensive overview on the use of this promising new category of plant biostimulants in agriculture and to highlight the current knowledge on their application prospects. Based on the prevailing state of the art, we aimed to roadmap MCB formulations from microalgae and cyanobacteria strain selection, algal biomass production, extraction techniques and application type to product commercialization and farmer and consumer acceptance. Moreover, we provide examples of successful trials demonstrating the beneficial applications of microalgal biostimulants as well as point out bottlenecks and constraints regarding their successful commercialization and input in sustainable agricultural practices. Full article
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