34 Follow us on @BetterFarmingON Better Farming | June/July 2024 crops: yield matter$ ALLEVIATING ABIOTIC STRESSES IN CROPS Ask yourself one question. ‘What problem am I try to solve?’ By Dale Cowan It’s estimated there are currently 1,200 companies globally developing and marketing biostimulants. This means there are literally thousands of products to choose from. What is a biostimulant? The United States Department of Agriculture’s (USDA) definition of a biostimulant differentiates the products from traditional crop inputs. “A plant biostimulant is considered a substance or microorganism that, when applied to seeds, plants, or the rhizosphere, stimulates natural processes to enhance or benefit nutrient uptake, nutrient efficiency, tolerance to abiotic stress, or crop quality and yield.” A popular tagline in promotion of these products would be “traditional products and biostimulants are better together.” The reduction in abiotic stresses is a key part of the USDA definition. There are references to the fact that abiotic stresses can influence up to 70 per cent of the final yield. Plant growth, biomass accumulation, and ultimately yield are simple functions of how much energy a plant can produce. When a plant has to divert energy to defend against stress or repair tissue damage, that is energy taken from growth and yield. When plants do encounter an abiotic stress such as too hot, too cold, too wet, too dry, or herbicide damage or soil compaction as examples, reducing the recovery time returns the crop to creating energy again for yield potential. What are some of the compounds that are used to reduce abiotic stresses in crops? The general categories are divided into products that impact the crop above ground and below ground. Above-ground products that are applied foliar can contain various seaweed extracts, chitin, amino acids, phenolics, and fulvic acids. The products targeted for below-ground functions at the root, and generally contain humic acids, soil bacteria usually classed as plant growth-promoting rhizobacteria (PGPR), and mycorrhizal fungi. The foliar products are often designed to be included in a tank mix with a traditional product. This becomes convenient and cost-effective in avoiding an extra pass to apply these products. Is it effective? Alleviating abiotic stresses can be hit or miss, as stresses are often transient. This may be one reason why the performance of these products is hard to predict, or the value is sometimes hard to detect with the absence of any measurable yield or crop quality increases. In my experience, products that are designed to be included in post-emergent herbicide application are the ones most likely to show a consistent yield response. Including these products in a tank mix with any Group 27 herbiAsk your crop advisor to understand how biostimulants can help you reach your cropping goals. Leslie Stewart photo
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