Strategies for mycorrhizal inoculation of six annual bedding plant species

We inoculated six common annual bedding plant species with the vesicular-arbuscular mycorrhizal fungus Glomus intraradices Schenck & Smith using two fertilizer P concentrations (3 or 15 mu g . mL(-1)) and three inoculation timings (inoculation at sowing, at transplanting, or at both times). The plant species used were: Salvia splendens F. Sellow ex Roem. & Schult. cv. Firecracker Rose; Impatiens walleriana Hook. f,cv. Sun and Shade Royal Red; Tagetes patula L. cv. Girls Golden; Petunia x hybrida Hort. Vilm.-Andr. cv. Freedom Blue; Coleus x hybridus Voss, cv, Jazz Salmon; and Viola x wittrockiana Gems. cv. Majestic Giant White. In general, Coleus, Petunia, and Viola were colonized more than were Impatiens, Tagetes, and Salvia. Inoculation at sowing required less inoculum than either of the other methods. Moreover, it was generally as effective in promoting colonization as double inoculation, and was often more effective than inoculation at transplanting. Mycorrhizal colonization was significantly reduced by the higher P concentration. The use of Myconate(R), a water-soluble form of the flavonoid formononetin, significantly stimulated colonization in Salvia.