2013 ASHS Annual Conference

Beneficial microorganisms, such as mycorrhizae and Trichoderma, are known for their benefits to plant growth and development.  Vesicular–Arbuscular Mycorrhizae (VAM) and Trichoderma fungi have been attributed to improve plant uptake of macro and micronutrients and enhance water availability. The main objective of this study was to examine the application of VAM and a commercial product, RootShield^TM containing Trichoderma harzianum, on the growth and development of Poinsettias. The study was conducted in the greenhouse in a completely randomized design with four treatments (Control, VAM, RootShield^TM, and VAM+RootShield^TM); two soil media (Sunshine Mix+vermiculite and Promix Bx Mycorise Pro+ vermiculite); and two fertilizer rates (recommended and 50% of the recommended rate of a slow release fertilizer), with four replications each. Poinsettia cuttings, 'Poi Cortez Burgundy', were obtained from Greenstreet Grower, Inc. Treatments were added at the time of transplanting. Plant height, root length, number of bracts, and shoot and root dry weight were determined. No significant variations were found between the two fertilizer rates. However, soil type and fertilizer rate influenced plant growth and development.  There was a significant difference in root dry weight and root length among treatments and media type when fertilizer was applied at the recommended rate. Significant differences were also found in root dry weight, shoot dry weight, and shoot height among treatments and media types when fertilizer was applied at the 50% recommended rate. More studies will be conducted to assess the effects of these beneficial microorganisms on poinsettia’s flower growth and development.