Effects of Ascophyllum nodosum extract on Vitis vinifera: Consequences on plant physiology, grape quality and secondary metabolism

Exploring Seaweed and Glycine Betaine Biostimulants for Enhanced Phenolic Content, Antioxidant Properties, and Gene Expression of Vitis vinifera cv. "Touriga Franca" Berries

Climate change will pose a challenge for the winemaking sector worldwide, bringing progressively drier and warmer conditions and increasing the frequency and intensity of weather extremes. The short-term adaptation strategy of applying biostimulants through foliar application serves as a crucial measure in mitigating the detrimental effects of environmental stresses on grapevine yield and berry quality. The aim of this study was to evaluate the effect of foliar application of a seaweed-based biostimulant (A. nodosum-ANE) and glycine betaine (GB) on berry quality, phenolic compounds, and antioxidant activity and to elucidate their action on the secondary metabolism. A trial was installed in a commercial vineyard (cv. "Touriga Franca") in the Cima Corgo (Upper Corgo) sub-region of the Douro Demarcated Region, Portugal. A total of four foliar sprayings were performed during the growing season: at flowering, pea size, bunch closer, and veraison. There was a positive effect of GB in the berry quality traits. Both ANE and GB increased the synthesis of anthocyanins and other phenolics in berries and influenced the expression of genes related to the synthesis and transport of anthocyanins (CHS, F3H, UFGT, and GST). So, they have the potential to act as elicitors of the secondary metabolism, leading to improved grape quality, and also to set the foundation for sustainable agricultural practices in the long run.

Biodegradable Mulch Films and Bioformulations Based on Trichoderma sp. and Seaweed Extract Differentially Affect the Metabolome of Industrial Tomato Plants

The use of biostimulants and biofilms in agriculture is constantly increasing, as they may support plant growth and productivity by improving nutrient absorption, increasing stress resilience and providing sustainable alternatives to chemical management practices. In this work, two commercial products based on Trichoderma afroharzianum strain T22 (Trianum P®) and a seaweed extract from Ascophyllum nodosum (Phylgreen®) were tested on industrial tomato plants (Solanum lycopersicum var. Heinz 5108F1) in a field experiment. The effects of single and combined applications of microbial and plant biostimulants on plants grown on two different biodegradable mulch films were evaluated in terms of changes in the metabolic profiles of leaves and berries. Untargeted metabolomics analysis by LC-MS Q-TOF revealed the presence of several significantly accumulated compounds, depending on the biostimulant treatment, the mulch biofilm and the tissue examined. Among the differential compounds identified, some metabolites, belonging to alkaloids, flavonoids and their derivatives, were more abundant in tomato berries and leaves upon application of Trichoderma-based product. Interestingly, the biostimulants, when applied alone, similarly affected the plant metabolome compared to control or combined treatments, while significant differences were observed according to the mulch biofilm applied.

Ascophyllum nodosum Extract and Glycine Betaine Preharvest Application in Grapevine: Enhancement of Berry Quality, Phytochemical Content and Antioxidant Properties

The Douro Demarcated Region (DDR) has peculiar edaphoclimatic characteristics that provide a suitable terroir for premium wine production. As climate change effects continue to emerge, ensuring productivity and quality becomes increasingly important for viticulturists, as those directly determine their profits. Cultural approaches, such as the use of biostimulants, are actively being developed to mitigate abiotic stress. The main objective of this work was to assess the effect of foliar sprays of a seaweed (Ascophyllum nodosum)-based extract (ANE) and glycine betaine (GB) on grape berry quality, bioactive compounds, and antioxidant activity. A trial was installed in a commercial vineyard (cv. 'Touriga Franca') in the Douro Superior (Upper Douro) sub-region of the Douro Demarcated Region. In 2020 and 2021, three foliar sprayings were performed during the growing season, namely at pea size, bunch closure, and veraison. There was a positive effect of both biostimulants (ANE and GB) on the physiological and biochemical performance of cv. 'Touriga Franca' exposed to summer stress. In general, the GB 0.2% spraying was the most promising treatment for this grape cultivar, as it increased berry quality, the concentration of bioactive compounds (total phenolics, flavonoids, and ortho-diphenols), and the antioxidant activity. These results revealed the efficacy of biostimulant sprayings as a sustainable viticultural practice, improving berry quality under summer stress conditions.

Holistic understanding of the response of grapevines to foliar application of seaweed extracts

Viticulture is highly dependent on phytochemicals to maintain good vineyard health. However, to reduce their accumulation in the environment, green regulations are driving the development of eco-friendly strategies. In this respect, seaweeds have proven to be one of the marine resources with the highest potential as plant protective agents, representing an environmentally-friendly alternative approach for sustainable wine production. The current work follows an interdisciplinary framework to evaluate the capacity of Ulva ohnoi and Rugulopteryx okamurae seaweeds to induce defense mechanisms in grapevine plants. To our knowledge, this is the first study to evaluate Rugulopteryx okamurae as a biostimulator . This macroalgae is relevant since it is an invasive species on the Atlantic and Mediterranean coast causing incalculable economic and environmental burdens. Four extracts (UL1, UL2, RU1 and RU2 developed from Ulva and Rugulopteryx, respectively) were foliar applied to Tempranillo plants cultivated under greenhouse conditions. UL1 and RU2 stood out for their capacity to induce defense genes, such as a PR10, PAL, STS48 and GST1, mainly 24 hours after the first application. The increased expression level of these genes agreed with i) an increase in trans-piceid and trans-resveratrol content, mainly in the RU2 treated leaves, and, ii) an increase in jasmonic acid and decrease in salicylic acid. Moreover, an induction of the activity of the antioxidant enzymes was observed at the end of the experiment, with an increase in superoxide dismutase and catalase in the RU2-treated leaves in particular. Interestingly, while foliar fungal diversity was not influenced by the treatments, alga extract amendment modified fungal composition, RU2 application enriching the content of various groups known for their biocontrol activity. Overall, the results evidenced the capacity of Rugulopteryx okamurae for grapevine biostimulation, inducing the activation of several secondary metabolite pathways and promoting the abundance of beneficial microbiota involved in grapevine protection. While further studies are needed to unravel the bioactive compound(s) involved, including conducting field experiments etc., the current findings are the first steps towards the inclusion of Rugulopteryx okamurae in a circular scheme that would reduce its accumulation on the coast and benefit the viticulture sector at the same time.

Chemical Composition, Biomolecular Analysis, and Nuclear Magnetic Resonance Spectroscopic Fingerprinting of Posidonia oceanica and Ascophyllum nodosum Extracts

A detailed analysis of the elemental and molecular composition of Posidonia oceanica (PO) and Ascophyllum nodosum (AN) is presented. In particular, an in-depth study of the molecular identification via NMR spectroscopy of aqueous and organic extracts of PO and AN was carried out, exploiting 2D COSY and pseudo-2D DOSY data to aid in the assignment of peaks in complex 1D proton NMR spectra. Many metabolites were identified, such as carbohydrates, amino acids, organic acids, fatty acids, and polyphenols, with NMR complementing the characterization of the two species by standard elemental analysis, HPLC analysis, and colorimetric testing. For PO, different parts of the live plant (roots, rhizomes, and leaves) were analysed, as well as the residues of the dead plant which typically deposit along the coasts. The combination of the various studies made it possible to recognize bioactive compounds naturally present in the two plant species and, in particular, in the PO residues, opening the door for their possible recycling and use in, for example, fertilizer. Furthermore, NMR is proven to be a powerful tool for the metabolomic study of plant species as it allows for the direct identification of specific biomarkers as well as providing a molecular fingerprint of the plant variety.

Impact of climate change on grape berry ripening: An assessment of adaptation strategies for the Australian vineyard

Compressed vintages, high alcohol and low wine acidity are but a few repercussions of climate change effects on Australian viticulture. While warm and cool growing regions may have different practical concerns related to climate change, they both experience altered berry and must composition and potentially reduced desirable wine characteristics and market value. Storms, drought and uncertain water supplies combined with excessive heat not only depress vine productivity through altered physiology but can have direct consequences on the fruit. Sunburn, shrivelling and altered sugar-flavour-aroma balance are becoming more prevalent while bushfires can result in smoke taint. Moreover, distorted pest and disease cycles and changes in pathogen geographical distribution have altered biotic stress dynamics that require novel management strategies. A multipronged approach to address these challenges may include alternative cultivars and rootstocks or changing geographic location. In addition, modifying and incorporating novel irrigation regimes, vine architecture and canopy manipulation, vineyard floor management, soil amendments and foliar products such as antitranspirants and other film-forming barriers are potential levers that can be used to manage the effects of climate change. The adoption of technology into the vineyard including weather, plant and soil sensors are giving viticulturists extra tools to make quick decisions, while satellite and airborne remote sensing allow the adoption of precision farming. A coherent and comprehensive approach to climate risk management, with consideration of the environment, ensures that optimum production and exceptional fruit quality is maintained. We review the preliminary findings and feasibility of these new strategies in the Australian context.

Biostimulation can prime elicitor induced resistance of grapevine leaves to downy mildew

Using plant defense elicitors to protect crops against diseases is an attractive strategy to reduce chemical pesticide use. However, development of elicitors remains limited because of variable effectiveness in the field. In contrast to fungicides that directly target pathogens, elicitors activate plant immunity, which depends on plant physiological status. Other products, the biostimulants, can improve certain functions of plants. In this study, the objective was to determine whether a biostimulant via effects on grapevine physiology could increase effectiveness of a defense elicitor. A new methodology was developed to study biostimulant activity under controlled conditions using in vitro plantlets. Both biostimulant and defense elicitor used in the study were plant extracts. When added to the culture medium, the biostimulant accelerated the beginning of plantlet growth and affected the shoot and root development. It also modified metabolomes and phytohormone contents of leaves, stems, and roots. When applied on shoots, the defense elicitor changed metabolite and phytohormone contents, but effects were different depending on whether plantlets were biostimulated or controls. Defense responses and protection against Plasmopara viticola (downy mildew agent) were induced only for plantlets previously treated with the biostimulant, Therefore, the biostimulant may act by priming the defense elicitor action. In this study, a new method to screen biostimulants active on grapevine vegetative growth was used to demonstrate that a biostimulant can optimize the efficiency of a plant defense elicitor.

A dual-omics approach for profiling plant responses to biostimulant applications under controlled and field conditions

A comprehensive approach using phenomics and global transcriptomics for dissecting plant response to biostimulants is illustrated with tomato (Solanum lycopersicum cv. Micro-Tom and Rio Grande) plants cultivated in the laboratory, greenhouse, and open field conditions. Biostimulant treatment based on an Ascophyllum nodosum extract (ANE) was applied as a foliar spray with two doses (1 or 2 l ha^-1) at three different phenological stages (BBCH51, BBCH61, and BBCH65) during the flowering phase. Both ANE doses resulted in greater net photosynthesis rate, stomatal conductance, and fruit yield across all culture conditions. A global transcriptomic analysis of leaves from plants grown in the climate chamber, revealed a greater number of differentially expressed genes (DEGs) with the low ANE dose compared to the greater one. The second and third applications induced broader transcriptome changes compared to the first one, indicating a cumulative treatment effect. The functional enrichment analysis of DEGs highlighted pathways related to stimulus-response and photosynthesis, consistent with the morpho-physiological observations. This study is the first comprehensive dual-omics approach for profiling plant responses to biostimulants across three different culture conditions.

Biostimulants as an Alternative to Improve the Wine Quality from Vitis vinifera (cv. Tempranillo) in La Rioja

The application of biostimulants appears to be an environmentally friendly, innovative, and sustainable agronomical tool to mitigate the negative effects induced by adverse climatology in traditional grape-growing regions such as La Rioja (Spain). However, their mechanism of action in grapevines is still unclear. We evaluated how commercial substances (two from Ascophyllum nodosum extraction and one amino acids-based biostimulant) and the non-proteinogenic amino acid β-aminobutyric acid (BABA) affect the quality and quantity of musts and grapes in Vitis vinifera L. cv. Tempranillo from a semi-arid region of La Rioja during two seasons. We hypothesized an enhancement in organic metabolites in berries and leaves in response to these treatments, changing the organoleptic characteristics of the final products. The treatments altered the primary metabolites such as carbohydrates, organic acids (AcOrg), and free amino acids, first in the leaves as the effect of the foliar application and second in grapes and musts. As the main result, the biostimulant efficiency depended on the climatology and vineyard location to improve the final yield. Whereas biostimulant application enhanced the yield in 2018 (less dry year), it did not help production in 2019 (dry year). BABA was the most efficient biostimulant, enhancing plant production. Regarding yield quality, the biostimulant application improved the musts mainly by enhancing the fumaric acid content and by reducing carbohydrates, except in BABA-treated plants, where they were accumulated. These results corroborate biostimulants as an exciting approach in wine production, especially for improving wine quality.

The Phenolic Composition of Hops (Humulus lupulus L.) Was Highly Influenced by Cultivar and Year and Little by Soil Liming or Foliar Spray Rich in Nutrients or Algae

The interest in expanding the production of hops outside the traditional cultivation regions, mainly motivated by the growth of the craft brewery business, justifies the intensification of studies into its adaptation to local growing conditions. In this study, four field trials were undertaken on a twenty-year-old hop garden, over periods of up to three years to assess the effect of important agro-environmental variation factors on hop phenol and phenolic composition and to establish its relationship with the elemental composition of hop cones. All the field trials were arranged as factorial designs exploring the combined effect of: (1) plots of different vigour plants × year; (2) plots of different plant vigor × algae- and nutrient-rich foliar sprays × year; (3) plot × liming × year; and (4) cultivars (Nugget, Cascade, Columbus) × year. Total phenols in hops, were significantly influenced by most of the experimental factors. Foliar spraying and liming were the factors that least influenced the measured variables. The year had the greatest effect on the accumulation of total phenols in hop cones in the different trials and may have contributed to interactions that often occurred between the factors under study. The year average for total phenol concentrations in hop cones ranged from 11.9 mg g−1 to 21.2 mg g−1. Significant differences in quantity and composition of phenolic compounds in hop cones were also found between cultivars. The phenolic compounds identified were mainly flavonols (quercetin and kaempferol glycosides) and phenolic carboxylic acids (p-coumaric and caffeic acids).

Influence of abscisic acid, Ascophyllum nodosum and Aloe vera on the phenolic composition and color of grape berry and wine of 'Cabernet Sauvignon' variety

In viticulture, various techniques can be used to improve productivity, tolerance to biotic or abiotic stress, the quality of grapes and wines such as the use of plant regulators and biostimulants. Thus, the objective of this work was to evaluate the effect of application of abscisic acid (S-ABA), Ascophyllum nodosum (A. nodosum) seaweed extract and Aloe vera (A. vera) gel on phenolic composition and chromatic characteristics of grapes from the 'Cabernet Sauvignon' variety. The experiment was conducted in a commercial vineyard in Campo Largo - Paraná, in two consecutive seasons, 2017/18 and 2018/19, involving the following treatments: 1) control; 2) (S-ABA) 400 mg/L; 3) S- ABA 600 mg/L; 4) A. vera gel 200 mL/L; 5) A. vera gel 400 mL/L; 6) seaweed extract 0.2 mL/L; 7) seaweed extract 0.4 mL/L. Two applications were performed with the seaweed extract and A. gel when the bunches were at veraison stage (50 and 75% of grape berries with coloration). Total anthocyanins content, total polyphenols content and activity of phenylalanine ammonia-lyase (PAL), polyphenoloxidase and peroxidase enzymes were assessed in the berries skin. Total anthocyanins, individual anthocyanins and total polyphenol contents as well as lightness, chroma and hue angle were analyzed in the corresponding wines. S-ABA increased the content of anthocyanins and total polyphenols, as well as the activity of PAL in the first season. A. nodosum (AN) seaweed extract increased the total polyphenol content, total anthocyanins content and PAL in the berry skin of 'Cabernet Sauvignon' variety. S-ABA increased the total polyphenol content and anthocyanins in wine, as well as the A. nodosum, in at least one of the evaluated seasons.

Trattamenti fogliari con Arthrospira platensis in viticoltura: primi risultati da esperimenti in campo

Biostimulants are increasingly assuming a key role in viticulture, thanks to the well-known ability to influence the physiological behavior of plants, promoting the quality of the grapes and improving vine response to abiotic stress. Seaweed extracts are among the most used and studied biostimulants, while there are very few cyanobacterial-based biostimulants currently available on the market. This work had the purpose of investigating the effects of an extract of Arthrospira platensis on eco-physiology, water potential, yield and quality of grapes in Vitis vinifera Experiments were conducted in open field (seasons 2017 and 2018) in Tuscany, carrying out foliar treatments with the A. platensis extract 20 days and ten days before the expected harvest. Following the treatments, gas exchanges and water potential were monitored, and berry samples were collected to evaluate the technological and phenolic quality of the grapes. In general, the treatments only marginally influenced gas exchanges and water potential, with diversified results in relation to the seasonal climatic trend (2017 season, hot and drought; 2018 milder season), indicating a more conservative behavior of the treated vines compared to the control vines. In addition, A. platensis always increased the berry weight, maintaining unchanged or improving the technological and phenolic quality of the grapes at harvest compared to the control. Although no univocal response to treatment emerges, the results globally suggest a positive impact of the leaf distribution of A. platensis on the eco-physiology and quanti-qualitative characteristics in V. vinifera candidating cyanobacteria for the formulation of new biostimulants.

The Role of Biostimulants as Alleviators of Biotic and Abiotic Stresses in Grapevine: A Review

The viticulture and wine industry contribute to the economy and reputation of many countries all over the world. With the predicted climate change, a negative impact on grapevine physiology, growth, production, and quality of berries is expected. On the other hand, the impact of these changes in phytopathogenic fungi development, survival rates, and host susceptibility is unpredictable. Grapevine fungal diseases control has been a great challenge to winegrowers worldwide. The use of chemicals in viticulture is high, which can result in the development of pathogen resistance, increasingly raising concerns regarding residues in wine and effects on human and environmental health. Promoting sustainable patterns of production is one of the overarching objectives and essential requirements for sustainable development. Alternative holistic approaches, such as those making use of biostimulants, are emerging in order to reduce the consequences of biotic and abiotic stresses in the grapevine, namely preventing grape fungal diseases, improving grapevine resistance to water stress, and increasing yield and berry quality.

Towards a Better Understanding of the Potential Benefits of Seaweed Based Biostimulants in Vitis vinifera L. Cultivars

Globally, 7.4 million hectares of arable land is planted with grapevine with a farm gate value of $68.3 billion. The production of grapes faces growing pressure associated with challenges such as climate change, diminishing resources as well as the overuse of chemical fertilizers and synthetic pesticides, which have an impact on sustainability. Consequently, viticulture has over the years embraced and implemented various practices such integrated pest management, organic and biodynamic farming to curb the high chemical inputs typically used in conventional farming. Biostimulants and biofertilizers are considered environmentally friendly and cost-effective alternatives to synthetic fertilizers and plant growth regulators. Seaweed is of particular interest because of its availability globally. It was reported that brown seaweed (Ascophyllum spp.) improves plant growth and agricultural productivity, hormonal signalling, and an improved secondary plant metabolism. It also provides an alternative to soil supplementation, avoiding some of the negative effects of fertilizers through the leaching of nutrients into groundwater sources. This review aims to provide a summary of the use of seaweed extracts in grape production and their influence on grapevine physiology and stress adaptation mechanisms.

Biostimulants in Viticulture: A Sustainable Approach against Biotic and Abiotic Stresses

Climate change and disproportionate anthropogenic interventions, such as the excess of phytopharmaceutical products and continuous soil tillage, are jeopardizing viticulture by subjecting plants to continuous abiotic stress. One of the main physiological repercussions of abiotic stress is represented by the unbalanced redox homeostasis due to the overproduction of reactive oxygen species (ROS), ultimately leading to a state of oxidative stress (detrimental to grape quality). To these are added the direct and indirect damages caused by pathogens (biotic stresses). In light of this scenario, it is inevitable that sustainable techniques and sensitivity approaches for environmental and human health have to be applied in viticulture. Sustainable viticulture can only be made with the aid of sustainable products. Biostimulant (PB) applications (including resistance inducers or elicitors) in the vineyard have become interesting maneuvers for counteracting vine diseases and improving grape quality. These also represent a partial alternative to soil fertilization by improving nutrient absorption and avoiding its leaching into the groundwater. Their role as elicitors has important repercussions in the stimulation of the phenylpropanoid pathway by triggering the activation of several enzymes, such as polyphenol oxidase, lipoxygenase, phenylalanine ammonia-lyase, and peroxidase (with the accumulation of phenolic compounds). The present review paper summarizes the PBs' implications in viticulture, gathering historical, functional, and applicative information. This work aims to highlight the innumerable beneficial effects on vines brought by these products. It also serves to spur the scientific community to a greater contribution in investigating the response mechanisms of the plant to positive inductions.

Influence of seaweed foliar application to Tempranillo grapevines on grape and wine phenolic compounds over two vintages

The study of seaweeds is increasing in viticulture due to their implications on plant protection and grape quality. This trial aimed to study the effects of foliar applications of an Ascophyllum nodosum extract at low (0.25%, v v-1) and high (0.50%, v v-1) dosages on grape and wine phenolic compounds in 2017 and 2018. In grapes, seaweed biostimulation increased the content of malvidin-3-glc, myricetin-3-glc and myricetin-3-gal in 2017 season. Moreover, both treatments improved the synthesis of trans-piceid and total stilbenes in both seasons. Sensory analysis revealed that 2017 wines had more color than the 2018 wines, which coincided with color intensity parameters. Therefore, seaweed applications to grapevines improved stilbenes content in grapes independently of the season and its effects on the rest of phenolic compounds in grapes and wines depended strongly of season factor.

Effects of Several Preharvest Canopy Applications on Yield and Quality of Table Grapes (Vitis vinifera L.) Cv. Crimson Seedless

Modern viticultural areas are being confronted with the negative impacts of global warming on yield and fruit composition, with especially adverse effects on anthocyanin synthesis. Novel and sustainable tools, such as biostimulants, may represent a viable alternative to traditional cultural practices, thus promoting eco-friendly strategies to enhance the yield, fruit quality and abiotic stress tolerance of grapevines. ‘Crimson Seedless’ is a late-season red table grape variety, and due to climatic warming, its berries are frequently failing to acquire the commercially acceptable red color. Canopy applications of different biostimulants, namely, Kelpak^®, Sunred^®, Cytolan^®, LalVigne™ Mature as well as Ethrel^® Top, were tested on grapevine cv. Crimson Seedless grown under semi-arid Mediterranean conditions in order to evaluate their effects on yield and fruit quality. Some of the products were sprayed in canopies at labeled doses, and some were applied at doses reported in other studies. For the control treatment, canopies were sprayed with water. Sampling started at veraison and was repeated at 10-day intervals to measure the evolution of berry weight, length and diameter, as well as the total soluble solids and titratable acidity of the juice. The grapes were harvested when the berries of one of the treatments attained the commercially acceptable color. The greatest improvements in the red berry color were achieved with Sunred^® (at a dose of 4 L ha⁻¹) and Ethrel^® Top (250 ppm plus glycerol at 1%), each applied at veraison and 10 days later. The different applications had varying effects on productivity and qualitative parameters. Only Sunred^® improved the accumulation of anthocyanin and the overall acceptability of table grapes by consumers. The obtained results clearly demonstrate that applying Sunred^® can improve the yield and qualitative parameters of the red table grape variety ‘Crimson Seedless’, indicating that this biostimulant could be a viable alternative to the most widely used plant growth regulator, ethephon.

Plant Biostimulants from Cyanobacteria: An Emerging Strategy to Improve Yields and Sustainability in Agriculture

Cyanobacteria can be considered a promising source for the development of new biostimulants as they are known to produce a variety of biologically active molecules that can positively affect plant growth, nutrient use efficiency, qualitative traits of the final product, and increase plant tolerance to abiotic stresses. Moreover, the cultivation of cyanobacteria in controlled and confined systems, along with their metabolic plasticity, provides the possibility to improve and standardize composition and effects on plants of derived biostimulant extracts or hydrolysates, which is one of the most critical aspects in the production of commercial biostimulants. Faced with these opportunities, research on biostimulant properties of cyanobacteria has undergone a significant growth in recent years. However, research in this field is still scarce, especially as regards the number of investigated cyanobacterial species. Future research should focus on reducing the costs of cyanobacterial biomass production and plant treatment and on identifying the molecules that mediate the biostimulant effects in order to optimize their content and stability in the final product. Furthermore, the extension of agronomic trials to a wider number of plant species, different application doses, and environmental conditions would allow the development of tailored microbial biostimulants, thus facilitating the diffusion of these products among farmers.

Seaweeds in viticulture: a review focused on grape quality

Cell walls of seaweeds contain a wide number of organic and inorganic constituents, of which polysaccharides have important biological activity. Some researchers suggest that polysaccharides from seaweeds can behave as biotic elicitors in viticulture, triggering the synthesis of phenolic compounds in leaves and grape berries. The mechanism of action of seaweeds after a foliar application to grapevines is not fully understood but it is discussed in this review. An overview of the recent research focused on the effects of seaweeds foliar applications on grapevine productivity, on grape and wine quality is included as well as a short-term future perspective for the research in this field.

Effects on must and wine volatile composition after biostimulation with a brown alga to Tempranillo grapevines in two seasons

BACKGROUND

Seaweed application has been defined as a novel technique capable of improving the content of secondary metabolites in berries. There is limited available information about its effects on must and wine volatile composition. This field trial aimed to study the effects of biostimulation to Tempranillo grapevines through an Ascophyllum nodosum fertilizer applied at a low dosage (Ld) and high dosage (Hd) on must and wine volatile compounds over two seasons.

RESULTS

Ld treatment scarcely affected must and wine volatile compounds in both seasons. Hd foliar application increased the content in musts of several individual terpenoids, C13 norisoprenoids, esters, benzenoids, alcohols, carbonyl compounds and C6 compounds in 2018. Must yeast assimilable nitrogen conditioned the production of wine volatile compounds.

CONCLUSION

These results suggest that seaweeds applications can act as elicitors in Tempranillo, triggering the synthesis of several compounds by the plant in musts during a season with a high rainfall and relative humidity. © 2020 Society of Chemical Industry.

Grapevine Stimulation: A Multidisciplinary Approach to Investigate the Effects of Biostimulants and a Plant Defense Stimulator

The increasing use of plant defense stimulators (PDS) and biostimulants (BS) to make agriculture more sustainable has led to questions about their action on plants. A new PhysBioGen approach is proposed with complementary tools: PHYSiological (root weight); BIOchemical and BIOlogical (secondary metabolite quantification and Plasmopara viticola development) and expressions of 161 GENes involved in metabolic plant functions. The proposed approach investigated the effects of three phytostimulants on Vitis vinifera: one PDS (ASM) and one BS chelated (CH) and another enriched with seaweed (SW). Distinct responses were obtained between the PDS and the two BS. In particular, we observed the persistence of anti-mildew efficacy over time, correlated with differentiated expressions of defense genes (VvROMT, VvSAMT, VvPR8). As expected, the two BS displayed more similarities to each other than to the PDS (flavonols, anthocyanins, free salicylic acid). However, the two BS revealed differences in the modulation of genes involved in defense and primary metabolism and some genes were identified as potential markers of their action (VvWRKY1, VvLOX9, VvPOD, VvPDV1, VvXIP1, VVDnaJ). Our results highlight the common and the specific effects of the two BS and the PDS. These new tools could help in understanding the mode of action of phytostimulants in order to achieve better quality and production yield and/or as a way to limit chemical inputs in the vineyard.

Effects of Arthrospira platensis Extract on Physiology and Berry Traits in Vitis vinifera

Several advantages on physiology, productivity, and grape quality have been reported for grapevine treated with seaweed extracts, but little is known about the importance of cyanobacterial-based biostimulants in viticulture. The purpose of this pioneering work was to analyze the broad-spectrum effects of the Arthrospiraplatensis F&M-C256 extract on Vitis vinifera L. cv. Pinot Nero grown in pots in optimal conditions and under water stress. To evaluate the effects, major physiological parameters of the plants and the quali-quantitative parameters of grape were analyzed. According to the results obtained in this study, ameliorating effects in leaf gas exchanges induced by A. platensis F&M-C256 treatments were detected in both irrigation regimes. Above all, A. platensis F&M-C256 allowed keeping stomata open without negative consequences in water potential in treated vines under water-stress conditions. In terms of berry traits, A. platensis F&M-C256-treated vines presented higher berry weight in comparison with untreated vines in both water regimes and improved berry composition in treated vines subjected to drought. The results of the present study demonstrated an A. platensis-dependent physiological response in case of abiotic stress, which prominently affects grape traits at harvest.

Combining Molecular Weight Fractionation and Metabolomics to Elucidate the Bioactivity of Vegetal Protein Hydrolysates in Tomato Plants

The comprehension of the bioactive fractions involved in the biostimulant activity of plant derived protein hydrolysates (PH) is a complex task, but it can also lead to significant improvements in the production of more effective plant biostimulants. The aim of this work is to shed light onto the bioactivity of different PH dialysis fractions (PH1 < 0.5-1 kDa; PH2 > 0.5-1 kDa; PH3 < 8-10 kDa; PH4 > 8-10 kDa) of a commercial PH-based biostimulant through a combined in vivo bioassay and metabolomics approach. A first tomato rooting bioassay investigated the auxin-like activity of PH and its fractions, each of them at three nitrogen levels (3, 30, and 300 mg L^-1 of N) in comparison with a negative control (water) and a positive control (indole-3-butyric acid, IBA). Thereafter, a second experiment was carried out where metabolomics was applied to elucidate the biochemical changes imposed by the PH and its best performing fraction (both at 300 mg L^-1 of N) in comparison to water and IBA. Overall, both the PH and its fractions increased the root length of tomato cuttings, compared to negative control. Moreover, the highest root length was obtained in the treatment PH1 following foliar application. Metabolomics allowed highlighting a response to PH1 that involved changes at phytohormones and secondary metabolite level. Notably, such metabolic reprogramming supported the effect on rooting of tomato cuttings, being shared with the response induced by the positive control IBA. Taken together, the outcome of in vivo assays and metabolomics indicate an auxin-like activity of the selected PH1 fraction.

Eco-Physiological Traits and Phenylpropanoid Profiling on Potted Vitis vinifera L. cv Pinot Noir Subjected to Ascophyllum nodosum Treatments under Post-Veraison Low Water Availability

In Mediterranean regions, extreme weather conditions during the growing season may alter grapevine physiology and metabolism, thus modifying the quality of wines. The objective of this study was to investigate the effects of Ascophyllum nodosum treatments on plant physiology and berry metabolism in Vitis vinifera exposed to water stress. The experiment was performed on potted vines subjected to two irrigation regimes (well-watered, WW, and water stressed, WS) both associated with A. nodosum treatments (SWE), compared with control plants (CTRL). Gas exchanges, chlorophyll fluorescence, and water relations were monitored on SWE and CTRL leaves, both in WW and WS vines at three times. Moreover, the quantification of secondary metabolites and their partitioning were performed in berry skins. Plants treated with A. nodosum extract showed higher photosynthesis and stomatal conductance than CTRL in both irrigation regimes and maintained a better plant hydraulic conductivity at the end of the sampling period. In addition, secondary metabolites in berry skins and their partitioning were significantly affected by the treatments in both irrigation regimes. Our results suggest that foliar application of A. nodosum extract may help the acclimation of grapevines to post-veraison water stress, likely improving plant physiological and biochemical performances under environmental constraints.

Seaweed foliar applications at two dosages to Tempranillo blanco (Vitis vinifera L.) grapevines in two seasons: Effects on grape and wine volatile composition

The effects of seaweed applications to grapevines on grape and wine volatile composition are currently unknown. The aim of this work was to study the influence of seaweed foliar applications (Ascophyllum nodosum) to a Tempranillo blanco vineyard on grape and wine volatile composition. A low (Ld) and a high dosage (Hd) of the seaweed fertilizer was applied in two consecutive seasons (2017-2018). The most abundant family of varietal volatile compounds in Tempranillo blanco grapes was C13 norisoprenoid. Hd treatment tended to increase the concentration of certain C6 compounds in grapes in both seasons, whereas Ld application tended to decrease 2-phenylethanol and 2-phenylethanal content in grapes with a season dependence. Season factor affected to the concentration of most of the volatile compounds in grapes due to the differences on rainfall, which affected to the weight of 100 berries and physico-chemical parameters. Yeast assimilable nitrogen (YAN) in musts could have affected the concentration of most of the wine volatile compounds. According to odor activity values (OAV), Tempranillo blanco wines were characterized as floral, fruity, banana, pear, among others aroma compounds.

Phenolic composition of Tempranillo Blanco (Vitis vinifera L.) grapes and wines after biostimulation via a foliar seaweed application

BACKGROUND

Seaweeds are defined as novel elicitors in many crops, allowing the synthesis of secondary metabolites to be triggered in different plant tissues. Currently, the phenolic composition of Tempranillo Blanco grapes and wines is unreported. The present study aimed to investigate the effects of an Ascophyllum nodosum seaweed extract applied to Tempranillo Blanco grapevines, at low (Ld) and high (Hd) dosages, on grape and wine phenolic compounds during two consecutive seasons (2017-2018).

RESULTS

The results obtained showed that catechin was the most abundant phenolic compound in Tempranillo Blanco grapes and wines. Season affected the weight of 100 berries and some enological parameters. Catechin and flavonols concentrations in grapes were increased after Hd application to grapevines, independently of season. The concentration of hydroxycinnamic and hydroxybenzoic acids in wines was affected by vintage, probably as a result of oxidation reactions, as well as pinking phenomena, whereas the stilbenes content in wines was conditioned by the affect of cryptogamic diseases in grapes.

CONCLUSION

Seaweeds might act as an elicitor of several phenolic compounds in grapes, enhancing the content of some phenolic compounds in wines. © 2019 Society of Chemical Industry.

Metabolic and transcriptional changes associated with the use of Ascophyllum nodosum extracts as tools to improve the quality of wine grapes (Vitis vinifera cv. Sangiovese) and their tolerance to biotic stress

BACKGROUND

Recent studies report that Ascophyllum nodosum extracts, once applied on the canopy of different crops, deliver positive effects, increasing yield, inducing tolerance to biotic stress, and improving the quality of products. However, the mechanisms of action are still unclear. In this research, vines subjected to multiple foliar applications of an A. nodosum extract (ANE) at label doses were compared with untreated vines (NTV) in accordance with a comparative approach. The investigation coupled a field experiment with a second trial conducted under semi-controlled conditions, to clarify the mechanisms of action involved.

RESULTS

The biostimulant did not affect soluble solids or the acidity of grapes; instead, it improved their anthocyanin and phenolic concentrations and the respective profiles. At the time of harvest, anthocyanin, and phenolic concentration were increased by 10.4% and 14.5%, respectively, when compared to the NTV. These effects correlated with a specific modulation of genes involved in the flavonoid metabolic pathways. Moreover, grapes from ANE vines witnessed a significant reduction in the spreading of gray mold when they were either assessed in field conditions or in vitro, compared to the grapes of NTV vines. This was related to a significant upregulation of the defense-related genes of the plant.

CONCLUSIONS

Overall, the results showed that A. nodosum extracts can be valuable tools in viticulture considering the emergence of challenging environmental conditions; hence, the regulation of specific metabolic pathways is the mechanism of action that leads to an increased tolerance of biotic stress and of changes in the content of grape metabolites. © 2019 Society of Chemical Industry.

Towards Sustainable Agriculture—Agronomic and Economic Effects of Biostimulant Use in Common Bean Cultivation

Today, one of the greatest challenges faced by the agriculture industry is the development of sustainable and environmentally-friendly systems to meet nutritional demands of the continuously growing global population. A number of research studies have recently been undertaken with the aim to indicate types of parameters used in plant production that would be able to improve plant growth as well as the effectiveness and quality of yield, and to help plants cope with environmental stress. The aim of this study was to verify a hypothesis that the implementation of a sustainable agricultural technology, based on the use of synthetic biostimulants, will allow not only increasing crop yield and quality but also improving the cost-effectiveness of common bean cultivation. The field experiment was conducted in three growing seasons (2016–2018). In the growing season, the plants were treated with Atonik and Tytanit biostimulants in the form of single or double spraying. We determinated biometric traits, seed yield, seed number, and 1000-seed weight. Further analyses included contents of nutraceutical potential. The economic effect of using biostimulants was also calculated. The results of our experiment allowed verifying a hypothesis that the implementation of a sustainable agricultural technology based on the use of synthetic preparations was an effective method to increase plant productivity and, consequently, economic profits to farmers.

Omeprazole alleviates water stress in peppermint and modulates the expression of menthol biosynthesis genes

Water stress is a worldwide agricultural challenge that limits crop growth and quality. Chemical compounds that promote tolerance to water stress, such as omeprazole showed recently promising results. The present study investigates the effect of weekly drenching applications of 0, 10, 50, 100, or 200 μM omeprazole on Mentha piperita (peppermint) subjected to water stress by watering at 100%, 70%, and 50% of container substrate capacity for 7 weeks in an experiment that spanned two seasons. Peppermint that received higher doses of omeprazole showed increased plant height, leaf number, leaf area, and dry weight under normal and water stress conditions. The amounts of chlorophyll and proline in the leaves as well as gas exchange increased in omeprazole-treated plants relative to the control plants. Omeprazole treatment also resulted in increased activity of the enzymes catalase and ascorbate peroxidase, reduced accumulation of the reactive oxygen species hydrogen peroxide, increase in the essential oil ratio, and improvement in essential oil composition. Omeprazole-treated plants showed higher ratios of menthol and menthone composition relative to the control plants. The changes in essential oil composition were associated with increased expression of genes associated with the menthol biosynthesis pathway. These findings indicate that omeprazole can ameliorate water stress in peppermint by increasing vegetative and root growth; increasing chlorophyll amount, photosynthetic rate, and gas exchange; reducing water loss by boosting leaf water potential and relative water content; increasing proline content; and modulating the gene expression of secondary metabolites.