Biostimulants promote plant growth and development throughout the crop cycle from seed germination to plant maturity in a number of ways. These include stimulating the natural plant processes, acting on specific aspects of plant metabolism and demonstrating the following benefits in plants, says Yara:
improving yield quantity and quality (e.g. sugar content, colour, etc), increasing plant tolerance to abiotic stresses, improving nutrient availability, uptake and assimilation into roots and shoots.
Biostimulants’ mode of action largely depends on the different bioactive compounds present in the product. For example, in seaweed extract-based biostimulants, specific polysaccharides, such as fucoidan, are priming the plant to tolerate abiotic stress while humic substances-based biostimulants can induce a hormone-like activity in plants and improve nutrient availability.
One of the main claims for many biostimulants is their positive effect on stress tolerance. The mode of action can vary depending on the biostimulant type and, in some cases, the exact mechanism which produces this effect is not yet clear.
In the case of seaweed extracts, anti-stress effects in a variety of stress situations, including temperature extremes, have been reported. Protective compounds in the seaweed extracts, such as antioxidants, could be involved.
Research shows soil temperature and water evaporation rate are stabilised by humic substances. The insulating properties of humic substances help maintain a more uniform soil temperature, especially during periods of rapid climatic changes, such as extreme temperatures. Because water is bound in the humic substances and they reduce temperature fluctuations, soil moisture is less likely to be released into the atmosphere.
Selection of the appropriate product for a particular crop and farm situation is based on several factors, such as crop development stage, application method, environmental conditions etc.
Each product has specific claims, for example stimulation of flowering or improved nutrient uptake, based on the effect it has on plants. So consulting your local agronomist will help you choose the most suitable product for your crop based on your needs.
Biostimulants can have a synergistic effect when applied together with fertilisers. For example, the use of humic substances improves nutrient uptake by increasing the cation exchange capacity of soil. Research has shown humic and fulvic acids are excellent foliar fertiliser carriers and activators. Foliar application of humic or fulvic acids in combination with trace elements and other plant nutrients can improve the growth of plant foliage and roots.