The Use of a Commercial Organic Biostimulant for Improved Production of Marigold Cultivars

A commercial extract of humic acids and kelp containing thiamine and L-ascorbic acid, both alone (ROOTS ) and combined with fertilizer (ROOTS PLUS"), was tested as a growth biostimulant. Tests were conducted with marigolds ('Climax', 'Crackerjack', 'Gay Ladies' and 'Nugget') under greenhouse and yield conditions. ROOTS" promoted earlier germination and produced better transplants with increased roo1 lengths and shoot heights Transplants removed Cram the greenhouse and transplanted to the field showed increased shoot height and increased earlier flowering when plants were treated monthly with ROOTS PLUS", as opposed to fertilizer alone. Transplants grown to maturity in the greenhouse and treated with ROOTS PLUS" flowered earlier. However, shoot height and shoot diameter were not significantly. different at maturity. ROOTS" appears to accelerate growth, leading to earlier reproduction. Based upon observations of increased lumen area in the xylem, we propose that the growth effect may result from increased permeability to water and nutrients. Biostimulant applications may lead to improved production of marigold bedding plants and earlier flowering.