Aquatic to agronomic: making progress towards mechanistic functional understanding of algal biostimulants for agriculture

With a growing human population, there is increasing demand for high-quality, high-volume food production, which has led to increasing environmental pressure. Productivity has been stimulated through increased reliance upon agrochemicals, unsustainable inorganic fertilisers, and finite mineral reserves. Algae and cyanobacteria are an incredibly biodiverse collection of organisms. They have been utilised by humans for centuries, including in agriculture. Currently, they are regarded as under-utilised sources of biomass which could benefit the agri-tech sector, owing to their potential to provide a myriad of plant growth promoting compounds including essential macro- and micro-nutrients and phytohormones that enhance stress tolerance in crops, alleviate desiccation stress, inhibit pathogenicity of pests in soils, and improve crop yield and quality. Despite a longevity of use, market availability, and renewed research interest in algal biostimulants, their efficacy and reproducibility vary and there is a lack of credible scientific evidence and availability of peer-reviewed empirical datasets. There are various unanswered questions and challenges to be addressed before algal biostimulants are more widely adopted into crop management and agriculture. Areas requiring greater understanding include: i) algal/cyanobacterial species selection; ii) cultivation practices, seasonality, and harvesting time on biomass composition; iii) biostimulants extraction methodologies; iv) application method, dosage, and frequency; v) effect on plants, soils, microbiomes, and productivity; vi) mode of action in plants and soils; and vii) circularity, economics, and environmental impact. Outcomes from this studentship will go a long way in understanding this ‘black box’ by undertaking a program of three main phases: Phase I (learning and biomass supply) – The current state-of-the-art of seaweed /microalgal cultivation, biomass harvesting and extraction, and biostimulant applications will be learned (In partnership with the industrial partner - Kilchoan Melfort Trust). Quantities of commercially representative microalgae, cyanobacteria, and seaweed biomass will either be produced or procured. Phase II (method and extraction development) – Biomass obtained from Phase I will be used to test best methods for extraction of high-value products (e.g., pigments) and as a raw feedstock for biostimulants. Whole biomass and resulting extracts will be characterised. Phase III (application) – Whole cell biomass (Phase I) and biostimulants extracts (Phase II) will be tested on a range of crops in either hydroponic or pot-trial systems. Most promising extracts will return to Phase II for extraction refinement and optimisation. Optional Phase IV (Techno-Economic/Life-Cycle Assessment) – Depending upon progress and results, the circularity of process and economic and environmental viability will be assessed, with recommendation for further areas of focus. New knowledge generated during this PhD studentship will help to identify where greater research, development, and investment is required to make the most meaningful industrial biotechnology impact. The proposed outcomes from this project are listed in detail in the posting. Director of Studies: Dr. Michael Ross (SAMS). Supervisory Team: Dr Puja Kumari (SAMS-UHI), Dr Alla Silkina (Swansea University), Marnik van Cauter (Kilchoan Melfort Trust). Funders: This four-year PhD studentship is equally funded by The Industrial Biotechnology Innovation Centre (IBioIC) and the Scottish Association for Marine Science (SAMS) and follows UKRI funding guidance.