Applications of Silicon and a Commercially Available Extract of the Brown Seaweed Ascophyllum nodosum Delayed Wilting In Greenhouse-Grown Petunia, Snapdragon, and Tomato

The greenhouse industry is continually looking for new technology to increase production quality and retail shelf- (postharvest-) life of containerized plants.  Abiotic stress tolerance is one of the important characteristics growers are looking to improve.  The objective of this trial was to test silicon (liquid potassium-silicate, Dyna-Gro Pro-TeKt) and a commercially available seaweed extract (Stimplex, Acadian Seaplants Limited) to help reduce wilting and improve visual appeal in potted plants after greenhouse production. Plants that wilt less and are more attractive will fare better in the retail market.  Silicon has been used to help mitigate both biotic and abiotic stresses in certain potted plants.  Seaweed extracts have also been used to manage stresses.  Both products may function in different ways that allows a synergistic effect between them. In this study we evaluated the effect of weekly 100 mL drenches of either silicon (100 mg·L^-1 Si), seaweed extract (5 mL·L^-1 Stimplex), or a combination of the two products. Control plants received only 100 mL clear-water drenches.  Seedlings of tomato, petunia, and snapdragon were transplanted and then grown for five weeks with weekly applications of silicon and/or seaweed extract prior to being moved to the post-harvest room.  Wilting was measured by taking periodic measurements of the leaf angle of the upper three most recently expanded leaves, and by determining a visual wilt index.  Weekly applications of either silicon or seaweed extract delayed wilting in tomato and snapdragon.  Seaweed extract, but not silicon, delayed wilting in Petunia.  The combination of both products was the most effective in delaying wilting of snapdragon.  Although few differences in growth parameters were measured, visually, the plants had different growth patterns, with the seaweed extract and silicon either alone, or together-treated plants being more attractive than the controls.  Tomato plants treated with either seaweed extract or silicon had stronger stems.  Recovery from wilt was similar between all treatments.  Applications of both silicon and seaweed extract showed potential as tools to reduce post-harvest wilting in container-grown plants.  Different species showed somewhat different response to each product or their combination, therefore species-specific information will need to be developed for the use of these products to extend postharvest life.