Scott W. Mattner1,2, Oscar N. Villalta1, Dylan J. McFarlane1,2, Md Tohidul Islam4, David M. Cahill4 and Tony Arioli3,4
1VSICA Research, Toolangi, VIC, Australia
2School of Agriculture, Biomedicine & Environment, La Trobe University, Bundoora, VIC, Australia
3Seasol, R&D Department, Baywater, VIC, Australia
4Department of School of Life & Environmental Sciences, Deakin University, Geelong, Victoria, Australia
We evaluated the effectiveness of a commercial seaweed extract from Durvillaea potatorum and Ascophyllum nodosum (Seasol®) on the yield, revenue and post-harvest rot of strawberry fruit in a series of field experiments. In the experiments, we treated strawberry plants (cv. Albion) monthly with a combined drench (10 L ha-1) and foliar spray (1:400) of the extract, compared with equivalent volumes of water as a control. In the strawberry nursery sector, use of the extract significantly increased the density of secondary roots (feeder roots) on harvested transplants by up to 22% and yields of marketable transplants by 8–19%. In the fruit sector, use of the extract significantly increased the root length density (root length per volume of soil) of strawberry plants by 38%, marketable fruit yields by 8-10%, and revenue from fruit by A$0.37-0.59 plant-1. Root length density at final harvest and marketable fruit yield of strawberry were highly correlated (r = 0.94), indicating a role of the extract in increasing the functionality of the root system. This was associated with a 9% increase in nitrogen-use efficiency by the crop. The extract significantly reduced the incidence and severity of post-harvest rots in strawberry fruit by 52% and 87%, respectively. The extract did not affect the firmness, soluble solids concentration (SSC), titratable acidity, or SSC:acid of strawberry fruit. In laboratory experiments, treatment with the extract increased the concentration of reactive oxygen species in strawberry roots. This provides evidence that the extract primes strawberry for tolerance against biotic and abiotic stress factors that affect disease, yield and quality.