Potato Review

www.potatoreview.com POTATO REVIEW MAY/JUNE 2021 25 BIOSTIMULANTS B IO-stimulants are gaining acceptance among growers as recognition of the role they play in promoting yields through greater nutrient uptake and improved plant health has led to a change in attitudes. is newfound appreciation owes much to the willingness of growers to test the products for themselves, but in many cases any scepticism is misplaced, according to Nick Winmill, potato specialist with adviser Agrii. e distrust of the past is perhaps understandable given the many forms of bio- stimulant available and for which the bene ts were not always clear. Overcoming this cynicism has taken time, but the development of better products and targeted trials intent on identifying when and how to best utilise their potential has brought commercial success. “Despite the lack of information about some products, there are others which have had years of development,” said Nick. “ ese are backed by several years of replicated trials and sound commercial use, showing exactly how they interact with the crop to support plant health and boost economic yield.” One example of a product where advances in crop nutrition and years of replicated trials have fostered a change in attitudes is ProAct, a soluble bio-stimulant that promotes calcium and silicone absorption through increased concentrations of the Harpin Alpha-Beta ( αβ ) protein. In potato crops, ProAct has delivered yield increases of 0.76-2.1 t/ha depending on the variety grown and whether the crop received one or two applications. “Harpins are a type of protein which function as elicitors, triggering the plant to activate key defensive and growth responses,” Nick said. “ ey are widespread and have demonstrable e ects in a wide range of plants, including potatoes.” Harpin αβ is a synthetic protein created from four di erent naturally occurring Harpin peptides in one molecule. It is produced by Plant Health Care and has been marketed as ProAct around the world for more than 15 years. e Harpin αβ protein in ProAct works by activating the ethylene signalling pathway within the plant. “When plants detect the Harpin αβ molecule, a cascade of biochemical signals are triggered throughout the plant,” said Dr Matthew Audley, Technical Sales Manager for Plant Health Care in the UK. “ ese signals tell the plant to accelerate growth, increase nutrient uptake and distribution, and reinforce abiotic stress resistance capacity. e Harpin αβ protein rapidly degrades within hours and does not leave any residues, but its positive e ects persist for weeks.” Higher calcium levels e Harpin αβ molecule stimulates the translocation of calcium ions, resulting in Potato specialist discusses the crop health and yield bene ts of using a biostimulant containing the protein Harpin αβ . ‘Trust the science’ “A weekly spray programme of ProAct at 100 g/ha showed significantly less blackleg than other treatments [in the trial].” Matthew Audley Nick Winmill ➜