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Growth hormones in seaweed extracts – Fact or fiction?




New studies are changing our understanding of the modes-of-action of seaweed extracts in crop production, shifting the focus to non-growth hormone molecules as the most likely drivers of effects observed. It is now emerging that polysaccharide molecules present in seaweed, also known as ‘bioactives’, are the most likely candidates responsible for the growth enhancing effects induced by seaweed extracts.


Why is this important? Because bioactives in seaweed have the potential to change the way we grow food globally and protect crops from challenges imposed by the climate crisis, such as extreme weather events and abiotic stresses such as drought, heat, cold, flooding and salinity. One pioneering technology in particular, SuperFifty® Prime,  achieves this by ‘priming’ and inducing molecular changes in crops, rendering them tolerant to abiotic stresses. The key components of this technology are natural bioactive compounds.


For many years, there was a prevailing view that growth hormones were present in seaweed extracts, and therefore could influence crop growth. However, that view is now changing. In a recent literature review published in the scientific journal, Biomolecules (Baltazar et al., 2021), scientists provided an overview of research undertaken on seaweed extracts, highlighting an emerging view in the scientific community that growth hormone levels in seaweed extracts are too low to invoke physiological responses in crops, particularly given the low application rates applied at field level. Research also suggests that certain growth hormones are undetectable in several seaweed extracts, indicating their potential absence in many cases. As such, there is a dearth of evidence supporting the “growth hormone theory” of how seaweed extracts influence crop physiology.


For decades, the mode of action of seaweed extracts has been investigated by means of bioassay, to determine the relative effect of seaweed extracts compared to known chemical standards. These studies suggested that application of certain seaweed extracts can improve plant growth, potentially comparable to effects observed when synthetic growth hormones are applied directly to plants. It was commonplace thereafter to refer to seaweed extracts as having “growth hormone-like activity”, with some suggesting that these effects were direct in nature due to the presence of growth hormones in seaweed extracts. It was also suggested that growth hormones in seaweed extracts originated from the seaweed itself, as certain algae species may produce low levels of phytohormones when they are alive. However, these hypotheses were not validated at the molecular level, leading scientists to question the growth hormone model of seaweed extract function and to design novel experiments to elucidate their true mode(s) of action. Although further studies suggested that seaweed extracts may work by modulating the expression and localization of growth hormones within plants, these studies did not demonstrate that such effects are due to the presence of hormones in seaweed extracts. Scientists therefore began to consider other non-growth hormone mechanisms.


Growing evidence exists to show that non-growth hormone components such as unique polysaccharide molecules present in seaweed are the most likely candidates responsible for the growth enhancing, biostimulant effects  induced by seaweed extracts.

Recent landmark peer reviewed papers co-authored by scientists at BioAtlantis and published in the journals Metabolites and the International journal of molecular sciences, show that a particular commercial Ascophyllum nodosum extract (Super Fifty®), which is high in polysaccharides, modulates a range of processes at the transcriptomic, metabolic and lipid levels (Omidbakhshfard et al., 2020, Staykov et al., 2021 and Rasul et al., 2021). The papers demonstrate that these changes involve multiple pathways and culminate in significant changes at the phenotypic level, including tolerance to oxidative stress and abiotic stresses; reductions in Reactive Oxygen Species (ROS); reductions in electrolyte leakage and increases in plant growth.  As such, new studies such as these are beginning to change our understanding of the modes of action of seaweed extracts and shifting the focus to specific polysaccharides and other non-growth hormone molecules as the most likely drivers of effects observed in plants.

The review published in Biomolecules was undertaken as part of the ‘NASPA’ project, an INTERREG Atlantic Area Programme, supported by the European Regional Development Fund.



BioAtlantis’ Super Fifty®, is the most concentrated Ascophyllum nodosum extract in the world and provide a means of mitigating against the effects of climate change such as drought, heat and cold. The recent peer reviewed studies co-authored by BioAtlantis reveal that treatment of plants with Super Fifty® prior to a stress alleviates oxidative stress-induced damages in crops. For more information on BioAtlantis’ new molecular priming tool, Super Fifty® Prime and how it can be utilized in climate-smart strategies to sustainably enhance crop production, please visit .



  • Baltazar M, Correia S, Guinan KJ, Sujeeth N, Bragança R, Gonçalves B. Recent Advances in the Molecular Effects of Biostimulants in Plants: An Overview. Biomolecules. 2021 Aug;11(8):1096.
  • Omidbakhshfard MA, Sujeeth N, Gupta S, Omranian N, Guinan KJ, Brotman Y, Nikoloski Z, Fernie AR, Mueller-Roeber B, Gechev TS. A biostimulant obtained from the seaweed Ascophyllum nodosum protects Arabidopsis thaliana from severe oxidative stress. International journal of molecular sciences. 2020 Jan;21(2):474.
  • Staykov NS, Angelov M, Petrov V, Minkov P, Kanojia A, Guinan KJ, Alseekh S, Fernie AR, Sujeeth N, Gechev TS. An Ascophyllum nodosum-derived biostimulant protects model and crop plants from oxidative stress. Metabolites. 2021 Jan;11(1):24.
  • Rasul F, Gupta S, Olas JJ, Gechev T, Sujeeth N, Mueller-Roeber B. Priming with a Seaweed Extract Strongly Improves Drought Tolerance in Arabidopsis. International journal of molecular sciences. 2021 Jan;22(3):1469.