Studies in the Genus Nectria-I. Factors Influencing Perithecial Formation in Culture

Abstract

Cultures of Nectria gliocladioides Smalley and Hansen, N. peziza Tode ex Fries, and N. ipomoeae Halsted were grown under different environmental conditions on both natural and synthetic media to determine some of the factors influencing perithecial production by these species in culture. Fruiting time in N. gliocladioides varied greatly, depending upon the medium. It was found that an increase in concentration of glucose, fructose or maltose gave increased numbers of perithecia and shorter fruiting time up to the 2.0% level; beyond this point fruiting decreased. Sucrose gave the same result, but only to the 1.0% level. Previous workers have found contrasting results for other Pyrenomycetes. Light was found to be necessary for fruiting in N. gliocladioides and N. peziza, but not in N. ipomoeae. Temperature also was important, with all three species fruiting best at 24[degree]C. In N. gliocladioides and N. ipomoeae stromal formation was dependent upon nutrition, and all gradations from no stroma to an extensive stroma could be found .-This is evidence that this character is too variable and unreliable to serve as a criterion for the genus Creonectria.