Effects of Vitamins and Nitrogen Sources on Asymbiotic Germination and Development of Orchis Laxiflora and Ophrys Sphegodes

Summary In order to assess the role of endophytic fungi in the germination and growth of wild European orchids, Orchis laxiflora Lamk. and Ophrys sphegodes Mill, were tested on asymbiotic strictly defined media. In spite of minor differences between the two species, a good development was obtained with both, if sucrose, organic nitrogen and vitamins were added to a basic mineral medium containing ammonium nitrate. Casein hydrolysate as an organic nitrogen source could be replaced successfully by a reconstitution of its amino acids or by glutamine. Among the vitamins tested thiamine proved to be necessary to Orchis laxiflora.