Commercial Seaweed Extract Research Articles

Reduced Effect of Commercial Leonardite and Seaweed Extract on Lettuce Growth under Mineral, Organic, and No Fertilization Regimes

In this study, two commercial products based on the main groups of contemporary biostimulants—a commercial leonardite and a seaweed extract—were tested with the objective of assessing the conditions under which they can enhance lettuce (Lactuca sativa L.) performance, particularly to determine if synergies with conventional fertilization methods can be observed. The experimental protocol was arranged as a factorial design with two factors: organic or mineral fertilization × plant biostimulant. The organic or mineral fertilization factor included five levels: two rates of a nitrogen (N) fertilizer (40 (Nmin40) and 80 (Nmin80) kg ha−1 of N), the same N rates applied as an organic amendment (Norg40 and Norg80), and an unfertilized control (N0). The plant biostimulants used were a commercial leonardite (leonardite) for soil application before planting, a commercial seaweed extract (algae) for foliar application during the growing season, and a control without plant biostimulant. Leonardite significantly increased lettuce dry matter yield (DMY) compared to the control only in the first growing cycle (11.5 and 13.5 g plant−1) and showed no significant interaction with conventional fertilization. It also consistently increased phosphorus (P) levels in the plant tissues. The seaweed extract did not show any effect on the plant, nor did it have any interactions with conventional fertilization regarding DMY. In contrast, with mineral fertilization, lettuce DMY increased from 8.0 and 4.0 g plant−1 (N0) to 22.2 and 12.0 g plant−1 (Nmin80) in the first and second growing cycles, respectively. The response to organic fertilization was lower, yet DMY still increased from 4.0 to 8.1 g plant−1 in the second growing cycle. Generally, this type of plant biostimulant is tested under some form of environmental stress, where it often yields positive results. In this study, the optimal cultivation conditions maintained for the lettuce in the pots likely explain the limited response to the biostimulants. This study suggests that the product labels should more clearly indicate whether they are recommended for general cultivation conditions or specifically for situations where a particular environmental stress can be anticipated.

A commercial seaweed extract increases growth performance, immune responses, and related gene expressions in whiteleg shrimp (Litopenaeus vannamei)

Seaweed liquid extracts are an attractive source of phytochemicals with high potential applicability in the aquafeed-additive industry. A commercial seaweed liquid extract (True Algae Max, TAM®), which has a marine seaweed odor, also dislplays significant levels of polysaccharides, phytochemicals, phenolic, and flavonoid compounds showing antioxidant activities and DPPH inhibition. This study investigates the impact of diets supplemented with TAM® as a functional additive on the growth, nutrient utilization, immune responses, and immune-related gene expressions of whiteleg shrimp (Litopenaeus vannamei). A total of 750 postlarvae (PL, with an average initial weight of 0.053±0.001 g) were divided into five experimental groups, comprising three replicates per dietary treatment. For an eight-week experimental period, all groups were fed identical diets except for the variation in TAM® inclusion levels. The basal diet (control diet) had no inclusion level of TAM® (TAM0%). Groups 2–5 each contain TAM® inclusion at levels of 1% (10 mL gk−1 diet TAM1%), 2% (20 mL gk−1 diet TAM2%), 3% (30 mL gk−1 diet TAM3%), and 4% (40 mL gk−1 diet TAM4%), respectively. The results concluded that TAM® has great potential as a feed additive for whiteleg shrimp, compared to the control group. The group TAM2% significantly achieved final weight (4.337 g), weight gain (4.287 g) specific growth rate (3.423% / day), feed conversion ratio (1.970), feed efficiency ratio (0.507), and protein efficiency ratio (1.407), compared to the control group (3.900 g, 3.850 g, 3.347%/day, 2.183, 0.458, and 1.270, respectively). Whole-body composition of protein and lipid contents were significantly improved by all TAM group including TAM2% (51.18% and 4.49%, respectively), compared to the control group (49.38% and 4.15%, respectively). As well as, shrimp in group TAM2% achieved the highest values of lysozyme (3.92 µg mL−1), superoxide dismutase (SOD, 11.92 IU mL−1), catalase (CAT, 13.04 IU g−1), lipase (31.24 IU L−1), and amylase (31.24 IU L−1), compared to the control group (3.19 µg mL−1, 8.80 IU mL−1, 10.84 IU g−1, 17.35 IU L−1, 21.65 IU L−1, respectively). For gene expressions experiment, four immune-related were performed in this study; Peroxiredoxin (Prx), Prophenoloxidase (PPO1), P53-like protein isoform delta (p53), and Hemocyanin subunit L5 (L5H). The results showed that shrimp in group TAM2% achieved the highest significant P53 gene transcription compared to the control group or the other TAM groups. Compared to other groups, the TAM1% group considerably increased PPO1 gene transcription, while TAM3% displayed the greatest Prx gene transcription. On the other hand, compared to control group, all TAM groups significantly improved L5H gene transcription. In conclusion, the current study revealed that TAM® diet supplementation (20 mL of TAM® per kg diet) represents a promising, eco-friendly, and sustainable feed additive in the shrimp aquadiet industry.

Application of commercial seaweed extract-based biostimulants to enhance adventitious root formation in ornamental cutting propagation protocols: a review

Despite significant advancements in stem-cutting propagation, insufficient rooting efficiency remains an economic burden for the ornamental nursery industry. IBA and NAA play a critical role in generating adventitious roots (AR) when applied exogenously. In sustainable agriculture, the substitution of chemical inputs, with alternative natural eco-friendly products presents a key challenge. Biostimulants can form part of a solution to mitigate such risks deriving from the use of agrochemicals, they are generally considered to be non-toxic, non-polluting, biodegradable, and non-hazardous. The current knowledge of the use of commercial seaweed extract (SE) products applied to ornamental cutting propagation has not been summarized until now. Therefore, we conducted a systematic review, and we hypothesized that SE-based biostimulant application to ornamental stem cuttings improves AR formation in terms of rooting percentage, root number, and architecture. Moreover, they increase the overall quality of a rooted cutting as dry biomass and organic compound content. The authors chose SE-based biostimulants because they have been proven to have an extremely low carbon footprint; moreover, they are expected to account for more than 33% of the global market for biostimulants and reached a value of 894 million Euros by 2022. This review focuses on (i) SE-based biostimulants, in particular, brown algae; (ii) technical information on five commercial products: Goteo®, Kelpak®, AlgaminoPlant, Bio Rhizotonic, Actiwawe and others, less known, also used as phytoregulators substitutes; (iii) applied protocols, describing dose, application method, number of treatments, cutting type; (iv) effects of applied protocols on rooting rate, root architecture and overall rooted cutting quality. Outcomes show that findings vary based on crops, cuttings, location, raw materials, composition, dose, application number and procedures, and growth environment.

The biostimulant effect of an extract from Durvillaea potatorum and Ascophyllum nodosum is associated with the priming of reactive oxygen species in strawberry in south-eastern Australia

AbstractStrawberry is an important horticultural crop in Victoria, Australia. Grey mould caused by Botrytis cinerea reduces marketable yield and post-harvest quality of strawberry fruit in the region. We conducted two field experiments in Victoria (Coldstream and Warburton) to evaluate the effectiveness of a commercial seaweed extract from Durvillaea potatorum and Ascophyllum nodosum (Seasol®) on the yield, revenue, and post-harvest rot of strawberry fruit. We applied the extract to strawberry crops (cv. Albion) monthly as a combined drench (10 L ha-1) and foliar spray (1:400), with water as a control. Application of the seaweed extract significantly increased strawberry fruit yields by 8-10% and revenue by AU$0.37-0.59 per plant. Furthermore, the extract significantly reduced the incidence and severity of post-harvest rots in strawberry fruit by 52-87%, respectively. The extract did not affect the firmness, soluble solids concentration (SSC), titratable acidity, or SSC:acid of strawberry fruit. In a separate laboratory experiment, we found that growing strawberry in the seaweed extract (1:400) increased the concentration of peroxidase by 50% and doubled H2O2 in roots soon after treatment. Increases in reactive oxygen species are an indicator of a suite of pathways associated with resistance and tolerance of biotic and abiotic stresses. Overall, the results demonstrate that the seaweed extract can act as a commercially-viable biostimulant for strawberry fruit production in south-eastern Australia.

Comparative study of the chemical composition and antifungal activity of commercial brown seaweed extracts.

A sustainable agriculture and the great increase in consumers of organic products in the last years make the use of natural products one of the main challenges of modern agriculture. This is the reason that the use of products based on seaweed extracts has increased exponentially, specifically brown seaweeds, including Ascophyllum nodosum and Ecklonia maxima. In this study, the chemical composition of 20 commercial seaweed extract products used as biostimulants and their antifungal activity against two common postharvest pathogens (Botrytis cinerea and Penicillium digitatum) from fruits were evaluated. Data were processed using chemometric techniques based on linear and non-linear models. The results showed that the algae species and the percentage of seaweed had a significant effect on the final composition of the products. In addition, great disparity was observed between formulations with similar labeling and antifungal effect of most of the analyzed products against some of the tested pathogens. These findings indicate the need for further research.

Improving Aerial and Root Quality Traits of Two Landscaping Shrubs Stem Cuttings by Applying a Commercial Brown Seaweed Extract

The availability of quality planting material is one of the most important requirements for increasing the productivity of any ornamental crop. Horticulturists make use of auxins and apply them exogenously to cuttings to generate adventitious roots and balanced shoots. Many studies have illustrated the influence of seaweed extracts on the growth of ornamental crops; their use in vegetative cutting propagation, to our knowledge, has been little investigated. Moreover, there is a lack of information on the influence of IBA and seaweed extract concentration on the carbohydrate content. This research aimed to compare the effects of the commercial seaweed extract, called Goteo®, with that of the phytohormone IBA, on the aerial and root quality traits of stem cutting in two Mediterranean landscaping shrubs: Lantana camara (S1) and Abelia × grandiflora (S2). The treatments applied to semi-hardwood stem cuttings were as follows: C0: untreated control; IBA concentration: 1250 mg L−1; Goteo® concentrations at 1, 2, and 3 mL L−1. In L. camara, the greatest values of rooting percentage were obtained under IBA and Goteo® treatments when compared to the control; in A. × grandiflora, there were no effects among treatments. The presented study shows that Goteo® stimulated adventitious rooting and provided a better rooting quality and shoot development of stem cuttings in Lantana and Abelia. In S1, cuttings treated with Goteo®, at the dose of 3 mL L−1, were greater in the number of roots, growth traits, root morphology and carbohydrate content, than those treated with IBA. In S2, 1 mL L−1 Goteo® concentration could be recommended to obtain high-quality rooted stem cuttings.

Enhancing Potato Production by Applying Commercial Seaweed Extract (TAM®) Biostimulant under Field Conditions

Enhancing Potato Production by Applying Commercial Seaweed Extract (TAM®) Biostimulant under Field Conditions

The Multifarious Endophytic Actinobacterial Isolate, Streptomyces tubercidicus UAE1, Combined With the Seaweed Biostimulant Further Promotes Growth of Avicennia marina

Mangrove (Avicennia marina) is a “green lung” tree growing along the Arabian Gulf coastline in the United Arab Emirates. Here, we aimed to determine the impact of the application of a commercial seaweed extract (SWE) biostimulant and endophytic actinobacterial isolates on growth performance and endogenous hormonal levels of mangroves. Therefore, we isolated endophytic plant growth-promoting (PGP) actinobacteria (PGPA) from mangrove roots and evaluated their potential as biological inoculants on mangrove seedlings under greenhouse and open-field nursery conditions. Seven salt-tolerant isolates had the ability to produce different levels ofin vitroplant growth regulators (PGRs) and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) and to solubilize phosphorus. Accordingly, only one isolate,Streptomyces tubercidicusUAE1 (St), was selected based on its relative superiority in displaying multiple modes of action and in successfully colonizing mangrove tissues for 15 weeks. In the greenhouse experiments, plants treated withStand SWE significantly (p< 0.05) improved dry biomass by 40.2% and 55.1% in roots and 42.2% and 55.4% in shoots, respectively, compared to seawater-irrigated non-treated mangrove plants (control). However,St+SWE caused a greater significant (p< 0.05) increase in dry weight of roots (67.6%) and shoots (65.7%) than did control plants. Following the combined treatment ofSt+SWE,in plantaPGR levels were found to be greatly enhanced over the non-treated control plants grown in non-SWE supplemented sediments, or plants inoculated with onlySt without the supplementation with SWE,or with non-inoculated plants grown in sediments supplied with SWE only. This was evident from the significant (p< 0.05) increases in the photosynthetic pigments and production of PGRs, as well as the reduction in the endogenous ACC levels of plant tissues compared to those in other treatments. Tissue nutrient contents of seedlings also increased by at least two-fold inSt+SWE treatment as compared to control. Similar effects were observed on all growth parameters under natural open-field nursery conditions. CombiningStwith SWE not only stimulates plant growth but also potentially has additive effects on mangrove ecosystem productivity in nutrient-impoverished soils in the Arabian coastal areas. This report is the first in the field of marine agriculture that uses SWE as a nutrient base for actinobacteria capable of producing PGRs and ACCD.

Germination screen for microalgae-generated plant growth biostimulants

Greenhouse (controlled environments) horticulture is expected to rise to ~USD 30 billion by 2023. In such climate-controlled systems, crop yields can increase ~10-fold compared with field production, due to higher water and nutrient efficiency and reduced external environmental impacts. The application of plant growth regulators (PGRs) can promote seed germination and plant development, speed up the production cycle and increase production efficiency which is of particular significance for high-value crops produced in controlled environments. Here, a novel in-vivo germination and plant growth assay was developed to rapidly identify microalgae strains that naturally produce PGRs was developed using spinach (Spinacia oleracea L) as test crop. Four newly isolated, fast growing microalgae strains in the genera Chlorococcum, Micractinium, Scenedesmus and Chlorella were screened to evaluate their potential as reliable and cost-effective sources of PGRs. Spinach seeds were primed with soluble and insoluble microalgae fractions from whole-cell and lysed-cell extracts and compared to controls (water and commercial seaweed extract). After a 5-day incubation, algae extracts improved seed germination up to 1.7-fold and 1.6-fold compared to water and seaweed extract, respectively. Green cotyledon emergence improved up to 2-fold (day 6), while seedling biomass improved up to 2.1-fold and 1.9-fold (day 9) compared to water and seaweed extract, respectively. The quantification of cytokinins (trans-Zeatin, DHZR, tZMP, iP, iPA, iPAMP), gibberellins (GA1, GA3, GA4, GA20 and GA29), auxin (IAA) and abscisic acid (ABA) validated that the four uncharacterized microalgal strains produced relevant PGRs. To boost plant propagation, PGR-producing microalgae may offer natural and cost-effective alternative biostimulants to synthetically produced agrochemicals.

Potentiality of Biofertilizers and Seaweed Extract on Growth & Yield of Sweet Corn (Zea mays L.)

The study aimed to understand and study the effect of commercial seaweed extract and other biofertilizers on the yield attributes and economics of cultivated sweet corn. The biofertilizers were applied as seed inoculants and seaweed extract was applied as foliar spray. Totally nine combination treatments were evaluated for their performance on the growth and yield of sweet corn and revealed that green cob yield (10.58 t/ha and plant height 145.99 cm at harvest ) was found to be significantly higher in treatment combination Azospirillum @10 gm/kg + PSB @10 gm/kg +5.0% Seaweed extract and was on par with Azospirillum @20 gm/kg +5.0% Seaweed extract (9.61 t/ha, plant height 143.01 cm). Cobs/plant, grains rows/cob, grains /cob and grains/row were also found highest in the treatment Azospirillum @10 gm/kg + PSB @10 gm/kg +5.0% Seaweed extract. Similarly with respect to stover yield and higher harvest index (34.50%) was noticed in PSB @20 gm/kg +10% Seaweed extract which was followed by Azospirillum @10 gm/kg + PSB @10 gm/kg +5.0% Seaweed extract (34.40%). The benefit cost ratio was highest in the treatment Azospirillum @10 gm/kg + PSB @10 gm/kg +5.0% (2.77) and lowest B:C ratio (1.2) was obtained in the PSB @20 gm/kg + water spray. These findings indicate that seaweed extract can generally be used as a safe potential multifunctional biofertilizer in the agricultural field. The use of seaweed and biofertilizer could potentially help mitigate the adverse effects of main nutrient deficiencies, diminishing the use of chemical fertilizers.

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

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

Interactive effects of plant growth-promoting rhizobacteria and a seaweed extract on the growth and physiology of Allium cepa L. (onion)

Detrimental effects caused by the overuse of synthetic agrochemicals have led to the development of natural biostimulants such as seaweed extracts and plant growth-promoting rhizobacteria (PGPR) being used as an alternative, environmentally-friendly technology to improve crop growth and increase agricultural yields. The present study aimed to investigate the interactions between PGPR and a commercial seaweed extract on the growth and biochemical composition of onion (Allium cepa). A pot trial was conducted under greenhouse conditions where onion plants were treated individually with the two PGPR, namely Bacillus licheniformis (BL) and Pseudomonas fluorescens (PF) and a seaweed extract Kelpak® (KEL) and combinations of KEL + BL and KEL + PF. Growth and yield parameters were measured after 12 weeks. KEL-treated plants showed the best growth response and overcame the inhibitory effects of BL treatment. KEL-treated plants also had the highest chlorophyll content. PGPR application improved the mineral nutrition of onion with these plants having the highest mineral content in the leaves and bulb. All biostimulant treatments increased the endogenous cytokinin and auxin content with the highest concentrations generally detected in the PF-treated plants. These results suggest that co-application of different biostimulant classes with different modes of action could further increase crop productivity with an improvement in both growth and nutrition content being achieved in onion with the co-application of a seaweed extract and PGPR.

The Potential of a New Commercial Seaweed Extract in Stimulating Morpho-Agronomic and Bioactive Properties of Eruca vesicaria (L.) Cav.

This study aimed to understand the effect of commercial seaweed extract as a biofertilizer, named True-Algae-Max (TAM®), on the yield, nutritional, antioxidant, and cytotoxic activity of Eruca vesicaria. Three concentrations of TAM® (5, 10, and 15%) were studied by foliar spray over the two cultivation years (2016 and 2017) without any chemical fertilizer, along with a control consisting of synthetic nitrogen, phosphorus and potassium (NPK) fertilizers. The yield and composition of E. vesicaria were significantly improved in all treatments, particularly at 10% concentration of TAM®, which resulted in maximum yield (1.99 kg m−2) and significant amounts of chlorophyll, carotenoids, phenolic compounds, flavonoids and total nutrients. Compared to the NPK control, E. vesicaria grown with 10% of TAM® improved total antioxidant activity from 41.80 to 49.36 mg g−1 and cytotoxicity from 25.30 to 60.40% with an IC50 value 85.7 µg mL−1 against the hepatocellular carcinoma cell line (HepG2). These findings indicate that seaweed extract can generally be used as a safe potential multifunctional biofertilizer in the agricultural field. The use of seaweed as a biofertilizer could potentially help mitigate the adverse effects of main nutrient deficiencies, diminishing the use of chemical fertilizers.

Effect of foliar application of liquid organic and inorganic fertilizers along with NAAon cowpea (Vigna unguiculata)

Cowpea (Vigna unguiculata) is popularly known as lobia in India, now cultivated throughout the tropics and sub-tropics and used as pulse, green vegetable, fodder, green manure and its productivity is 683 kg ha -1.Vermiwash is a liquid leachate that is collected after the passage of water through the column of worm action. It is a collection of excretory products and mucous secretion of earthworms along with micronutrients from the soil organic molecules. This bio-liquid is rich in nutrients, microorganisms, enzymes, vitamins and plant growth hormones which increase the resistant power of crops against various diseases and enhances the productivity of crops.. The nutrients present in vermiwash are in water-soluble form and meet the immediate requirements of crop plants. Further, it contains nitrogen fixing and nutrient solubilizing bacteria. Generally, foliar spray of vermiwash of vermicomposting supplies nutrients to higher plants more rapidly than soil and root application methods. Vermiwash spray persists on leaf surface and resulted in leaf thickness, increase in photosynthetic activity, internode growth, improved plant physiology and finally increased the yield (Selladuraiet al., 2009). Humic acid is a commercial product containing many elements which improve the growth and yield of cowpea. The fermented organic liquid fertilizer panchagavya contains nutrients, plant growth regulators and microorganisms which help in plant growth, yield, metabolic activities and gives resistant to pest and diseases. The commercial seaweed extract contains major and minor nutrients, amino acids, vitamins and other growth promoting substances. DAP is a complex fertilizer containing 18 % nitrogen and 46 % phosphorus. The Naphthalene acidic acid is a auxin and very effective in promoting growth and yield of pulses. It may be concluded from the results that the foliar application of 2 % DAP along with 40 ppm NAA is recommended to cowpea to enhance the yield and to obtain higher returns.

Seaweed extract to enhance marigold seed germination and seedling establishment

The brown seaweed Ascophyllum nodosum and seaweed-derived products have been widely used as nutrient additions, biofertilizer and biostimulant in horticultural crop systems. This study aimed to evaluate the effects of a seaweed extract obtained from whole brown algae (A nodosum) on seed germination and seedling growth of ornamental marigold (Tagetes erecta). The seeds of marigold were daily sprayed with 0 (control), 5, 10 or 15 mL L−1 commercial seaweed extract Acadian Seaplants™ (70 ml). The percentage, index and average time of seed germination, seedling height, fresh, dry mass of shoots, roots and root system morphology were evaluated. The results showed that the seaweed extract enhanced all parameters related to seed germination and seedling growth and development. The best results were obtained with 15 mL L−1 seaweed extract which increased by two-fold marigold seed germination and 84.00% seedling height, and both fresh and dry shoot mass and root morphology. We suggest algal extracts of Ascophyllum nodosum should be used as natural biostimulant on marigold crop, improving seed germination and seedling development.

The effects of drench and foliar application of a commercial seaweed extract on the leaf nutrient content of potato, Solanum tuberosum ‘BP1’

ISHS XXX International Horticultural Congress IHC2018: II International Symposium on Root and Tuber Crops: Value Added Crops for the Next Generation The effects of drench and foliar application of a commercial seaweed extract on the leaf nutrient content of potato, Solanum tuberosum 'BP1'

A commercial seaweed extract structured microbial communities associated with tomato and pepper roots and significantly increased crop yield.

SummarySeaweeds have been used as a source of natural fertilizer and biostimulant in agriculture for centuries. However, their effects on soil and crop root microbiota remain unclear. Here, we used a commercially available Ascophyllum nodosum extract (ANE) to test its effect on bacterial and fungal communities of rhizospheric soils and roots of pepper and tomato plants in greenhouse trials. Two independent trials were conducted in a split‐block design. We used amplicon sequencing targeting fungal ITS and bacterial 16S rRNA gene to determine microbial community structure changes. We find that productivity parameters of root, shoot and fruit biomass were positively and significantly influenced by the ANE amendment. In addition, a‐diversity differed significantly between amended and control plants, but only in some of the experimental conditions. Species composition among sites (b‐diversity) differed according to the amendment treatment in all four communities (fungal‐root, fungal‐soil, bacterial‐root and bacterial‐soil). Finally, we identified a number of candidate taxa most strongly correlated with crop yield increases. Further studies on isolation and characterization of these microbial taxa linked to the application of liquid seaweed extract may help to enhance crop yield in sustainable agro‐ecosystems.

Preliminary assessment on the effects of the commercial seaweed extract, AMPEP, on growth and thermal tolerance of the kelp Saccharina spp. from the Northwest Atlantic

Acadian Seaplants, Ltd., marine plant extract powder (AMPEP) is a commercially available extract derived from the brown seaweed, Ascophyllum nodosum. This extract is widely applied to increase the performance of land crops and has been reported to enhance growth of some seaweed crops. To assess the effects of AMPEP on the growth and thermal tolerance of Saccharina latissima and S. angustissima cultivars, we performed two experiments. First, juvenile sporophytes were dipped (i.e., 30 or 60 min) in AMPEP solutions of different concentrations (0.001, 0.005, 0.05, 1, and 5 g L−1). Sporophytes were then cultivated in half strength Provasoli’s enriched seawater (PES) and allowed to grow at different temperatures (12, 16, 19, 23, and 25 ± 1 °C) for 20 days using a temperature gradient table. Photoperiod was maintained at 12:12 L:D with photosynthetically active radiation (PAR) of 90 ± 10 μmol photons m−2 s−1. Results show a differential response between the two species tested. Sporophytes of both species cultured at 23 and 25 °C died during the first 7 days post dipping in AMPEP. After the 20-day period, the surviving sporophytes were transferred to an incubator set at 18 ± 1 °C (i.e., LT50 after 20 days). These sporophytes remained for 14 additional days to assess for any delayed effect on thermal tolerance, with treated sporophytes showing a higher percentage of survival and growth than control sporophytes never exposed to AMPEP. Furthermore, after the 14-day incubation at 18 °C, treated sporophytes of both species showed blades more than three times thicker than control sporophytes. These preliminary results indicate that AMPEP may enhance the growth capacity of S. latissima and S. angustissima when exposed to suboptimal temperatures, allowing them to overcome heat stress more effectively while maintaining growth.

Effect of several commercial seaweed extracts in the mitigation of iron chlorosis of tomato plants (Solanum lycopersicum L.)

Commercial seaweed extracts (SWEs) have been applied in agriculture for ameliorating biotic and abiotic stress in plants. However, the mechanisms of action of these extracts are only partially known. Most of the research work with SWEs has focused on abiotic stresses such as drought, salinity or high temperatures, but little is known about SWE effects on plants with nutrient imbalances. Therefore, the goal of this study was to investigate the effects of several commercial SWEs (based on Ascophyllum nodosum and Durvillea potatorum) in the mitigation of iron chlorosis of stressed tomato plants. Tomato plants were grown in a hydroponic system initially with Fe, and then Fe was removed from the nutrient solution. SWEs were applied twice, first during the growth period (+ Fe) and second at the beginning of Fe deficiency (− Fe), following the recommended doses of manufacturers. Some of SWE treatments activated the antioxidant system in Fe-deficient tomato plants increasing SOD and CAT activity. However, SWEs application did not produce positive effects on biomass, chlorophyll content, activation of Fe acquisition strategies and Fe uptake with respect to the untreated control.

Determination of gibberellic acid in a commercial seaweed extract by capillary electrophoresis

Gibberellic acid (GA 3 ) is an important plant growth regulator used in agriculture. This work has developed and validated a simple method for the quantification of GA 3 in a seaweed extract product using capillary electrophoresis with direct UV detection. A fused-silica capillary of 50 µm inner diameter and 30 cm of effective length with extended light path, 50 mmol.L -1 of borate buffer as background electrolyte solution (pH 9.11), voltage of +30kV applying hydrodynamic injection of 50 mbar for 5 s and length detection of 200 nm were employed. The method was validated according to the International Conference Harmonisation guidelines. Satisfactory results in the range of 10 – 100 mg.L -1 were obtained for precision (RSD below 3.62%), linearity (R 2 : 0.9976, lack of fit test p > 0.05), specificity and accuracy for which the limit of detection and quantitation were 3.07 and 9.29 mg.L -1 , respectively. The results indicate that the method is suitable for implementation in agroindustry in order to assure the quality control of GA 3 of seaweed products.