Biostimulant Treatments Research Articles

The seaweed Ascophyllum nodosum-based biostimulant enhances salt stress tolerance in rice (Oryza sativa L.) by remodeling physiological, biochemical, and metabolic responses

ABSTRACT This study explores the role of a biostimulant derived from the seaweed Ascophyllum nodosum (AN) in mitigating salt stress in rice plants. The weekly (S+W) and biweekly (S+B) biostimulant treatments exhibited enhanced shoot and root biomass, maintained ionic balance, and increased pigment content (total chlorophyll increased by 26.35% and 31%, carotenoids by 11.90% and 16.67% in S+W and S+B treatments, respectively) compared to untreated salt-stressed plants (CS). Improved gas exchange parameters and PSII efficiency were observed in S+W and S+B treatments. AN-biostimulant treatments mitigated salt-induced oxidative stress by positively regulating the antioxidant defense system. Notably, a strong negative correlation was observed between antioxidants and oxidative markers. Furthermore, AN-biostimulant treatments induced key metabolites (organic acids, sugars, amino acids, flavonoids), emphasizing the integrated role of multiple pathways in enhancing salt tolerance in rice. These findings highlight the potential of AN biostimulants as eco-friendly tools for crop enhancement in challenging environments.

Assessment of yield and nitrate content of wild rocket grown under salinity and subjected to biostimulant application

Soil secondary salinity due to irrigation is a condition that frequently occurs in Mediterranean areas, and negatively affects crop growth and yield. Biostimulants are proven to alleviate the detrimental effect of salinity on plant growth and production. Four increasing saline concentration levels of water irrigation reaching 6.0 dS m-1 (Electrical Conductivity - EC) were combined with foliar biostimulant treatments (tropical plants and a protein hydrolysate) in pots containing wild rocket. The combined effect of experimental factors improved the SPAD index with greater increases in the EC4 and EC6 plants (+9 and +12% compared to untreated, respectively) but also caused an increase in nitrate content (+48%, on average, compared to the untreated control) without exceeding the EC legal threshold. Overall, for the other parameters analyzed, the response of wild rocket both to application of both salinity and biostimulant was consistent with previous studies. Our results show that biostimulant effectiveness in alleviating the detrimental effect of salinity was not evident for all parameters analyzed. In addition, harvest time affected most parameters, showing the important role of growing conditions in modulating plant response to salinity stress when biostimulants are applied. Plant response thus seems to depend on biostimulant application (type, dose, timing), growing conditions, and genetic traits.

Biostimulant Application Alleviates the Negative Effects of Deficit Irrigation and Improves Growth Performance, Essential Oil Yield and Water-Use Efficiency of Mint Crop

The scarcity of water is limiting crop production and is one of the most important stressors that severely affects crop yield, and it may also decrease the quality of the final products. Most of the medicinal and aromatic plants are considered resilient to water stress and constitute a sustainable choice for crop production in arid and semiarid conditions. In the present study, we examined the effect of scheduled deficit irrigation (e.g., I1: 40% of field capacity); I2: 70% of field capacity; and I3: 100% of field capacity) combined with biostimulant application (four different products that consisted of nitrogenous compounds and carboxylic acids (M1); nitrogenous compounds and seaweed extracts (M2); humic and fulvic acids and seaweed extracts (M3); and CaO, SiO2, calcium mobilization and translocation factor and microminerals (M4)) on crop performance and essential oil production of mint plants (Mentha arvensis L.). Our aim was to define an irrigation regime that increases water-use efficiency and the biostimulant products that alleviate water stress effects. Our results indicate that moderate deficit irrigation (I2 treatment) and biostimulants that contained seaweed extracts and nitrogenous compounds and humic and fulvic acids (M2 and M3 treatments, respectively) significantly improved yield parameters in terms of fresh and dry herb yield and essential oil production. Moreover, the same biostimulant treatments significantly increased water-use efficiency of mint crops based on the various yield parameters tested in this study. In conclusion, our results indicate that selection of proper biostimulatory products may allow to apply deficit irrigation regimes in mint cultivation without compromising the crop performance in terms of both biomass production and essential oil yield. Therefore, the combination of these agronomic tools could facilitate water saving strategies in arid and semiarid regions and contribute to the sustainable management of water resources.

Biostimulant effects on the herbage yield and nutritive composition of a mixed ryegrass–clover pasture

Dairy producers are continuously searching for environmentally friendly and economically sustainable alternatives to increase pasture herbage yield and reduce reliance on chemical fertilisers. A possible means to reduce fertiliser reliance is the use of biostimulants. Biostimulants such as fulvic acid and bioflavonoids help to increase N uptake efficiency, thereby increasing herbage quantity and quality. The aim of this study was to determine the effects of a soil application of a carbohydrate-derived fulvic acid and bioflavonoid biostimulant on herbage yield and nutritive composition of a mixed perennial ryegrass–clover pasture. Biostimulant treatment resulted in a lower ryegrass component of the mixed sward, in both winter and summer grazing cycles. However, the nutritive composition and total herbage yield of the pasture were not significantly affected by biostimulant treatment. The treatment did show a tendency to affect total herbage yield within a season. This suggests that total herbage yield could be increased if additional N fertiliser is applied together with a biostimulant soil treatment, although further investigation is needed to confirm this postulation. Biostimulant treatments have the potential to lead to reduced fertiliser inputs on perennial ryegrass–clover pastures as they may increase nutrient uptake efficiency.

Efficacy of TUVA a growth biostimulant growth regulator based on plant origin amino acid blend and its impact on the performance of Tomato, Cucumber, and Paprika (Bell pepper) under Greenhouse Conditions

In a greenhouse study on tomato, cucumber, and paprika, the effectiveness of TUVA product, a biostimulant and plant growth regulator manufactured from plant-origin amino acids used as organic fertilizer, was assessed. The goal of this study was to determine whether using the TUVA biostimulant, which is based on soybean and seaweed extracts and contains rich microelements essential for plant growth, can ensure good crop yield and quality in tomato, cucumber, and paprika plants growth and productivity. Over six months, the study was held in Mersin, Turkey, at three distinct sites. We looked at the physiological reactions of tomato, cucumber, and paprika plants that were grown in greenhouses and given TUVA biostimulant treatments. The use of the TUVA biostimulant increased plant height by 15% and biomass by 20%, as well as the number of fruits produced and total yield (up to 20.2%). The findings demonstrated that the TUVA product considerably improved all three crops' tonnage, homogeneous size, fruit quantity, and earliness. The fruits' quality was also improved by the TUVA product, which increased their marketability. The findings demonstrate a substantial positive correlation (R=0.9) between the TUVA product and each of the three crops' properties. The correlation coefficients further demonstrate the significant relationship (p ≤0.05) among variables. According to the trial's findings, the TUVA product has promise as a plant growth regulator for usage in greenhouse environments. It can considerably (p ≤0.05) increase the productivity and quality of tomato, cucumber, and paprika crops, and it is safe to use. According to the findings of this research, TUVA is a promising novel growth biostimulant that has the potential to enhance the performance of tomato, cucumber, and paprika plants cultivated in greenhouse environments. The methods by which TUVA improves plant development and productivity need more investigation, but the results of this study indicate that TUVA is a useful tool for producers who want to raise the yield and quality of their crops.

Influence of hydrolyzed animal protein-based biostimulant on primary, soluble and volatile secondary metabolism of Genovese and Greek-type basil grown under salt stress

Basil is susceptible to stressful conditions, of which salinity is a major problem in agriculture, causing significant yield losses. Biostimulants can be used as stress reducers and can be used for sustainable agriculture. Genovese-type 'Marian' basil and Greek-type 'Manos' basil were grown under 100 mM NaCl salt stress conditions and treated with a hydrolyzed animal protein-based biostimulant (as foliar fertilizer and via a nutrient solution). Greek basil yield was positively affected in both biostimulant treatments. The irrigated biostimulant had a positive effect on primary metabolites in Genovese-type basil. Foliar application of the biostimulant resulted in higher glucose and ascorbic acid content (+23.8% and +25.7%, respectively) compared to the salt treatment of Greek basil. Phenolic content increased in both biostimulant-treated cultivars and ranged from +73.3% to +628.9%, depending on cultivar and treatment. Volatile content was most affected by the biostimulant added to the nutrient solution and was 18.5% higher in Greek basil and 111.5% higher in Genovese basil than in the salt treatment. With the results of our study, we have laid the foundation for further studies on the internal quality of herbs and which method of biostimulant application is more suitable for basil production under salinity conditions.

Multifarious microbial biostimulants promote growth in Arachis hypogaea L.

Plant Growth Promoting Rhizobacteria (PGPR), a microbial biostimulant has been widely studied to stimulate plant growth through induction of natural biological processes. However, lack of successful validation under open field remains a barrier to mark their standard in agriculture. Therefore, the aim of the research was to highlight the potential of PGPR biostimulants via in vitro studies and subsequently to demonstrate the in planta evaluation in oilseed crop, Arachis hypogaea L. (Groundnut) under pot and field trials. The two rhizobacterial strain was identified as Pseudomonas fluorescens and Bacillus subtilis by 16s rRNA gene sequence analysis. Both the strains were functionally screened for plant growth promoting traits. Pot and field trials were conducted where seeds were inoculated with PGPR biostimulants and harvested at 30 and 90 days. Biostimulant treatments were applied as single and co-inoculation in groundnut and the growth factors, biochemical parameters, yield, and seed quality were analyzed. The study inferred that the consortium of PGPR biostimulants significantly (p < 0.05) showed highest growth, photosynthetic pigments, nodulation status, leghaemoglobin content, yield attributes, and also biofortification of seed nutrients in oilseed crop under both pot and field conditions than un-inoculated control. This study supports the idea of the application of PGPR as microbial biostimulants through successful open field trial to facilitate its implementation as a feasible and potential agricultural product to synthetic fertilizers thereby influencing sustainable and stable crop production.

Assessment of the influence of soil inoculation on changes in the adaptability of maize hybrids

The aim of this paper is to present the results of the field trial carried out to collect and assess data on the interaction of maize (Zea mays L) genotypes and beneficial microorganisms. The small plot field trial consisting of untreated control plots and plots treated with biostimulants was conducted in three consecutive years (2019, 2020 and 2021). Yield is a particularly important trait from the aspect of maize breeding as well as maize production; therefore, the present study focused more closely on how it was influenced by the biostimulant treatments. The level of grain yield, grain moisture content at harvest and grain dry-matter content were observed and recorded as the components of yield. The nutritional value of kernels was also tested, and protein, oil and starch contents were analysed as the most important components of this trait. The results reflected that the treatment with biostimulants constituted from beneficial microorganisms can be listed among the factors influencing the grain yield, in addition to the seasonal effect, the genotype and the nutrient supply of the soil. The treatment with biostimulants, even on its own among the factors, had an impact on the quantity and components of yield, and on the characteristics determining the kernel nutritional value. The interaction between the genotypes and the interacting microorganisms is of specific importance. The most spectacular result was attained with the application of one of the biostimulants leading to elevated grain yield in 75% of the maize genotypes in the study, along with a kernel nutritive value equal to the control group over all of the three years of the trial.

Yield and Quality of Processing Tomato as Improved by Biostimulants Based on Trichoderma sp. and Ascophyllum nodosum and Biodegradable Mulching Films

Tomato is a great source of bioactive compounds, is important for human health, and is cultivated worldwide. However, the high inputs required for its cultivation must be sustainably managed in order to limit yield losses, thus obtaining high-quality and environmentally friendly production. In this perspective, we compared four biostimulant treatments, i.e., Ascophyllum nodosum extract—Bio; microbial biostimulant containing the micro-organism Trichoderma afroharzianum—Mic; a combination of both—M-B; not treated—Control) and three mulch treatments (biodegradable film Ecovio—ECO; biodegradable film MaterBi®—NOV; bare soil—BS) and evaluated their effects on yield and quality traits in processing tomato. Both biodegradable films elicited a 27.0% yield increase compared to plants grown on bare soil, and biostimulants determined a 23.7% increase over the Control, with the best performance recorded for M-B (+24.8%). Biodegradable MaterBi® film (NOV) was associated with higher total soluble solids (TSS) and firmness values (average of 4.9 °Brix and 1.30 kg cm−2, respectively), even if a significant effect of biostimulants was observed only for the second element. Carotenoid content was higher in non-treated plants grown on bare soil as well as hydrophilic antioxidant activity (AA), but in this case, no differences between biostimulant treatments were recorded. The lipophilic AA in NOV-treated plants was about six and four times higher than observed in BS and ECO treatments, respectively; NOV also caused a 38.7% increase in ascorbic acid content over the Control but was not different from ECO. All biostimulant treatments elicited a 30% increase in phenol content compared to Control plants. Our findings highlight that microbial biostimulants based on A. nodosum extract and T. afroharzianum (both applied singularly and combined) can be considered a sustainable tool for increasing yield and improve some quality traits of processing tomato; in addition, we also confirmed the capability of biodegradable mulches, in particular, MaterBi®, to enhance the agronomic performance of tomato.

Different Responses to Adventitious Rhizogenesis under Indole-3-Butyric Acid and Seaweed Extracts in Ornamental’s Cuttings: First Results in Photinia x fraseri ‘Red Robin’

Fraser’s photinia ‘Red Robin’ (Photinia x fraseri Dress, Rosaceae family) is an important primary ornamental landscaping species with optimal hedge or screen effects and low maintenance, but it is difficult to root when propagated by cuttings, although high concentrations of phytohormones are used to optimize rhizogenesis. To our knowledge, there is currently no feasible enhanced method for photinia vegetative propagation through stem cuttings, using seaweed extract-based biostimulants as root promoters. Given the economic importance of the species, this research aims to assess the effects of indole-3-butyric acid (IBA) and seaweed extract-based stimulators on the quality of photinia ‘Red Robin’ cuttings, in terms of rooting indicators and ground and aboveground agronomic features. The treatments applied were different concentrations of commercial rooting stimulators compared to an untreated control: C0: distilled water; Rhizopon AA: 1% IBA (R1); Kelpak®: 2 mL L−1 (K2); Kelpak®: 3 mL L−1 (K3); Goteo®: 2 mL L−1 (G2); Goteo®: 3 mL L−1 (G3). The first results showed different responses to adventitious rhizogenesis under IBA and both seaweed extract treatments. At 70 DAC (days after cutting), the seaweed extract stimulated the production of over 80% of cuttings with callus; at 240 DAC, the percentage of rooted cuttings treated under R1 was the highest = 34.3%; the worst results were obtained by both biostimulant treatments at the highest doses: K3 = 21.3% and G3 = 20.7%. Furthermore, R1 produced 3.07 roots per cutting, which was 50% higher than the average of all other treatments. The applications of Kelpak® and Goteo® biostimulants, at both concentrations, resulted in an inhibition of root length with values below the untreated control. Rooted cuttings under R1 showed the highest ground (0.35 g) and aboveground (0.47) dry value. Neither seaweed extract, Kelpak® or Goteo®, at different concentrations, improved both the ground and above-ground weights of rooted cutting, compared to the untreated control, indicating that these natural products are not suitable for Fraser’s photinia ‘Red Robin’ propagation using this methodology. The overall quality of cuttings in IBA treatment was the strongest, with 1%, being the optimum concentration. Further research must be conducted to propose effective agronomic protocols by investigating application methods, doses and number of applications, and to clarify the biochemical and molecular mechanisms of action of these seaweed extracts.

Different vegetal protein hydrolysates distinctively alleviate salinity stress in vegetable crops: A case study on tomato and lettuce.

Plants have evolved diverse plant-species specific tolerance mechanisms to cope with salt stress. However, these adaptive strategies often inefficiently mitigate the stress related to increasing salinity. In this respect, plant-based biostimulants have gained increasing popularity since they can alleviate deleterious effects of salinity. Hence, this study aimed to evaluate the sensitivity of tomato and lettuce plants grown under high salinity and the possible protective effects of four biostimulants based on vegetal protein hydrolysates. Plants were set in a 2 × 5 factorial experimental design completely randomized with two salt conditions, no salt (0 mM) and high salt (120 mM for tomato or 80 mM for lettuce), and five biostimulant treatments (C: Malvaceae-derived, P: Poaceae-derived, D: Legume-derived commercial 'Trainer®', H: Legume-derived commercial 'Vegamin®', and Control: distilled water). Our results showed that both salinity and biostimulant treatments affected the biomass accumulation in the two plant species, albeit to different extents. The salinity stress induced a higher activity of antioxidant enzymes (e.g., catalase, ascorbate peroxidase, guaiacol peroxidase and superoxide dismutase) and the overaccumulation of osmolyte proline in both lettuce and tomato plants. Interestingly, salt-stressed lettuce plants showed a higher accumulation of proline as compared to tomato plants. On the other hand, the treatment with biostimulants in salt-stressed plants caused a differential induction of enzymatic activity depending on the plant and the biostimulant considered. Overall, our results suggest that tomato plants were constitutively more tolerant to salinity than lettuce plants. As a consequence, the effectiveness of biostimulants in alleviating high salt concentrations was more evident in lettuce. Among the four biostimulants tested, P and D showed to be the most promising for the amelioration of salt stress in both the plant species, thereby suggesting their possible application in the agricultural practice.

Organo Mineral Fertilizers Increases Vegetative Growth and Yield and Quality Parameters of Pomegranate cv. Wonderful Fruits

In recent years, to improve sustainable production in horticultural crops, many new types of strategies have been developed, including organo-mineral fertilization to complement chemical fertilizers in order to enhance the nutritional status of plants and sustainability of the agroecosystems. This study was performed on a young pomegranate orchard of the “Wonderful” cultivar during the 2018 and 2019 seasons. The purpose was to evaluate the effects of three foliar applications (at the red ball, fruit setting, and fruit development stages) of four commercial organo-mineral fertilizers (Hendophyt®, Ergostim XL®, Siapton® 10L, and Allibio Rad®) on vegetative growth, yield, and several other physico-chemical parameters of the fruits, throughout each season. The results obtained showed several differences between the two years. The annual trunk growth of trees under all compared treatments showed significantly lower values in 2018 (average 9.7 mm) than in 2019 (average 11.8 mm). At the end of the two-year period, the biostimulant treatments resulted in significantly larger trunk diameters (average 43.6 mm) than the control (39.6 mm). Only in 2018, significantly higher number of fruits per tree, number of arils per fruit, edible part, and juice yield were obtained under biostimulant treatments compared with the control. No differences among treatments were observed for any color parameters or physico-chemical traits in the fruits for either year. In 2019, fruit morpho-pomological properties tended to be lower than in 2018, while in contrast, total phenol content and antioxidant activity were higher. The warmer and windier weather conditions of 2019 probably led to greater plant stress conditions, with a reduction in fruit size and an increase in the bioactive compounds of juice. In conclusion, due to the various positive results, foliar organo-mineral fertilizers could be recommended to improve the performance of pomegranate Wondeful cv. under similar conditions.

Biostimulants promote the accumulation of carbohydrates and biosynthesis of anthocyanins in 'Yinhongli' plum.

Biostimulants play an important role in promoting crop growth and development and improving fruit yield, but their influence on fruit quality in horticulture plants is still unclear. In this study, four types of biostimulants, Ainuo (AN), Aigefu (AG), Weiguo (WG), and Guanwu Shuang (GS) were applied to the fruit surface of 'Yinhongli' plum at 60 and 75 days after anthesis to investigate their effect on carbohydrates and biosynthesis of anthocyanins, and also analyze the relationship between sugar and anthocyanin accumulation during fruit color change to ripening. Results showed that all biostimulant treatments significantly improved fruit appearance quality, and increased single fruit weight and TSS/TA. Cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside, are the most important anthocyanins in the red skin of the 'Yinhongli' plum, and no anthocyanin was detected in the green skin. In addition, WG and GS treatments significantly increased the expression of structural genes involved in anthocyanin biosynthesis compared with the control, especially chalcone synthase (CHS) and flavonoid 3-O-glucosyltransferase (UFGT) at 95-105d after anthesis, leading to anthocyanin accumulation 10 days earlier than the control. Correlation analysis showed that there was a significant correlation between total sugar and anthocyanin content during fruit coloring and ripening.

Effect of Application of Biostimulants on the Biomass, Nitrate, Pigments, and Antioxidants Content in Radish and Turnip Microgreens

Microgreens are a functional food that is very appreciated for their good taste and product features. They are produced all year without fertilizers and pesticides. In this paper, the effects of the application of commercial and natural biostimulants on the yield and nutraceutical properties of turnip greens and radish microgreens were investigated. The experiment consisted of four treatments based on biostimulants (Bio-1: TRAINER®; Bio-2: AQUAMIN®; Bio-3: leaf moringa extract; C: distilled water (control)) applied in two species (turnip greens and radish). Fresh and dry biomass, nitrate content, pigments, antioxidants, and antioxidant activity were measured. All biostimulants promoted biomass (both fresh and dry) accumulation in the radish but not in turnip greens. The treatment with biostimulant did not affect plant growth in the radish, while a depressive effect of Bio-1 upon plant growth was observed in turnip greens (−19% smaller than control). In radish, Bio-3 led to microgreens with the highest chlorophyll a content (+75% with respect to the control). Bio treatments did not affect the Chl (a, b, total) content in turnip greens. Biostimulants significantly lowered the nitrate content compared to the control (−27% nitrates) and significantly promoted TPC (+19% over the control) in the radish. They also stimulated antioxidant activity (DPPH), with the highest value in Bio-1, in the turnip, and in Bio-2 and Bio-3, in the radish. Conclusively, biostimulant treatments showed a positive effect on microgreens and, in particular, on those of the radish, improving various nutraceutical parameters.

Effect of Protein Gel Treatments on Biometric and Biochemical Attributes of Tomato Seedlings in Greenhouse Condition

Protein hydrolysates are widely used in agricultural crops for improving plant nutrient uptake, growth, yield, and fruit quality. Tomato (Lycopersicon esculentum Mill.) is one of the most important vegetables consumed around the world both for its good taste and rich content in vitamins, minerals, lycopene, and β-carotene. The objective of the present study was to assess the effect of new stimulant products based on protein hydrolysates obtained from animal tissue by-products on tomato seedlings. Given the increased intake of amino acids, it is expected that this treatment will exert beneficial effects on the development of certain vigorous seedlings, representing the premise for obtaining superior tomato plants and the improvement of the production and quality of tomato fruit. Two variants of protein gels based on gelatin and keratin hydrolysates were obtained by processing bovine hide and wool and were used for periodical root applications on tomato seedlings cultivated in a greenhouse. During the experiment, the biometric characteristics of seedlings were measured weekly. The content of photosynthetic pigments, dry weight, sugars, and polyphenols were analyzed, and the antioxidant activity was assessed in the leaves. The research performed showed that applied biostimulant treatments increased the content of photosynthetic pigments by 10%, the content of sugars by 75%, and the content of polyphenols by 16% compared to the control untreated variant. Between the variants of protein gels tested, the best results were obtained by applying a mixture of bovine gelatin and keratin.

Bio-Growth Stimulants Impact Seed Yield Products and Oil Composition of Chia

Chia (Salvia hispanica L.) is a specialty crop capable of providing healthy food and metabolites. The goal of our study was to explore the possibility of expanding seed yield, oil production, and metabolites of chia in response to amino acid, barthenosteriode, and algae extract treatments used as bio-stimulants. The experiment was conducted in the field in a randomized complete block design with three repeats. The treatments were (1) control (spray only with water), (2) amino acids with nutrients (2 mL/L vs. 4 mL/L), (3) brassinolide (5 mL/L vs. 10 mL/L), and algae extract (2 mL/L vs. 4 mL/L). The growth and yield measurements of chia, such as chlorophyll, carotenoids, amino acids, indoles, phenols, macro- and micronutrients, carbohydrates, total oil, and fatty acids were analyzed. The chia plants sprayed with growth stimulant materials showed increases in most studied characteristics, particularly algae extract at 4 mL/L, followed by algae extract at 2 mL/L during the first and second seasons. Meanwhile, amino acids at 4 mL/L led to the third-highest increases in most cases. Conversely, all bio-stimulant treatments decreased total phenols in leaves (mg/100 g f.w.), especially seaweed at 4 mL/L, compared to high levels in the control during both seasons. Control plants showed the lowest levels of the measurements mentioned previously when scored by barthenosteriode at 5 mL/L during the first and second seasons. GLC for fixed oil in chia showed the recognition of four biocomponents. i.e., oleic, linoleic, palmitic, and α-α linolenic acids. The main biocomponent was α-α linolenic acid and reach (49.7 to 57.9%). The application of seaweed at 4 mL/L could be exploited to improve growth, seed crop, fixed oil production, chemicals and bio-constituents, especially the fixed oil composition of chia (Salvia hispanica L.) plant.

Biostimulants Promote Plant Development, Crop Productivity, and Fruit Quality of Protected Strawberries

Berries such as strawberries are recognized as a significant constituent of healthy human diets owing to their bioactive secondary metabolites. To improve crop sustainability, yield and berry quality, alternative production systems should be proposed such as organic farming and the use of biostimulants. Thus, we have compared within a complete randomized block design seven biostimulant treatments: 1-control, 2-seaweed extract, 3-Trichoderma, 4-mycorrhiza, 5-mixture of three bacteria, 6-combination of mycorrhiza + bacteria, and 7-citric acid. Strawberry plants were grown in conventional high tunnel (CH), conventional greenhouse (CG) and organic greenhouse (OG). Our results showed that biostimulants did not impact the soil microbial activity (FDA) when compared with the control. Leaf chlorophyll content and photosynthetic leaf performance were not affected by any studied biostimulants. Bacteria, citric acid, and the combination of mycorrhiza + bacteria increased the number of flowering stalks compared with the control in CH, while bacteria increased the crown diameter and all biostimulants increased fresh and dry shoot plant biomass. Citric acid increased leaf Ca content in CG, when all biostimulants increased leaf N content in CH. Studied biostimulants increased berry productivity in CH, while citric acid treatment had the highest yield in CG. The anthocyanins content increased with the use of biostimulants in CH, whereas Trichoderma (CG) and the combination of mycorrhiza + bacteria (OG) increased the Brix, total polyphenols, and anthocyanin contents of the berries compared with the control.

In-Vivo Biophoton Emission, Physiological and Oxidative Responses of Biostimulant-Treated Winter Wheat (Triticum eastivum L.) as Seed Priming Possibility, for Heat Stress Alleviation.

High temperature induces oxidative processes in wheat, the alleviation of which is promising using biostimulants. Priming has been used for enhancing stress tolerance of seedlings. However, the usage of biostimulants for priming is an unexplored area under either normal or stress conditions. Therefore, the aim of our study was to evaluate the heat stress alleviation capability of differentially applied biostimulant treatments on wheat seedlings. The investigation included stress parameters (fresh/dry weight ratio, chlorophyll content estimation, antioxidant capacity and lipid oxidation) combined with biophoton emission measurement, since with this latter non-invasive technique, it is possible to measure and elucidate in vivo stress conditions in real-time using lipid oxidation-related photon emissions. We confirmed that a single biostimulant pretreatment increased antioxidant capacity and decreased biophoton release and lipid oxidation, indicating the reduction of the harmful effects of heat stress. Therefore, biophoton emission proved to be suitable for detecting and imaging the effects of heat stress on wheat seedlings for the first time. Two-way analysis of variance (ANOVA) revealed that biostimulant (p = 4.01 × 10−7) treatments, temperature (p = 9.07 × 10−8), and the interaction of the two factors (p = 2.07 × 10−5) had a significant effect on the overall count per second values of biophoton emission, predicting more efficient biostimulant utilization practices, even for seed priming purposes.

Applying Biostimulants to Combat Water Deficit in Crop Plants: Research and Debate

Climate change has increased the severity of drought episodes by further reducing precipitation in vulnerable zones. Drought induces a substantial decrease in agricultural water, reducing crop yields. Consequently, addressing water consumption can increase farmers’ profits. This work describes lab-to-field research in Zea mays, using two biostimulants: glycine betaine (GB) and L-pyroglutamic acid (PG). The biostimulant optimal dosages were selected using a hydroponic system with 20% polyethylene glycol and nursery experiments under water-deficit irrigation. The established dosages were evaluated in field trials in which irrigation was reduced by 20%. Laboratory biostimulant optimisation showed in stressed treated seedlings (GB 0.1 mM; PG 1 mM) an increased dry weight, relative growth rate and water use efficiency, reducing seedling growth loss between 65 and 85%, respectively. Field trials using a GB-optimised dosage showed an increase in plants’ growth, grain yield and flour Ca content. In addition, grain flour carbohydrate content and protein remained similar to control well-watered plants. Finally, the economic aspects of biostimulant treatments, water consumption, water sources (ground vs. desalinated) and grain biomass were addressed. Overall, GB treatment demonstrated to be a valuable tool to reduce water consumption and improve farmers’ earnings.

Biostimulants on Crops: Their Impact under Abiotic Stress Conditions

Biostimulants are agronomic tools that have been gaining importance in the reduction of fertilizer applications. They can improve the yield of cropping systems or preventing crop yield losses under abiotic stresses. Biostimulants can be composed of organic and inorganic materials and most of the components are still unknown. The characterization of the molecular mechanism of action of biostimulants can be obtained using the omics approach, which includes the determination of transcriptomic, proteomic, and metabolomic changes in treated plants. This review reports an overview of the biostimulants, taking stock on the recent molecular studies that are contributing to clarify their action mechanisms. The omics studies can provide an overall evaluation of a crop’s response, connecting the molecular changes with the physiological pathways activated and the performance with or without stress conditions. The multiple responses of plants treated with biostimulants must be correlated with the phenotype changes. In this context, it is also crucial to design an adequate experimental plan and statistical data analysis, in order to find robust correlations between biostimulant treatments and crop performance.