Spore discharge rhythms in pyrenomycetes: IV. The influence of climatic factors

Abstract

In the field, spore discharge by Hypoxylon rubigirwsum, H. fuscum, Nectria ditissima, Lopadostoma turgidum and Diattypella aspera was largely confined to rain periods. Daldinia concentrica discharged spores continuously for 47 days, including 22 days without rain. Hypoxylon fragiforme maintained discharge for limited periods during dry spells. Spore discharge in all species was little affected by temperature and humidity but was almost completely inhibited by snow. In laboratory experiments, spore discharge was induced by ‘rain’, in Xylosphaera longipes, Nectria cinnabarina and Hypoxylon fragiforme . Experimental ‘drought’ stopped spore discharge in Xylosphaerapolymorpha, X. longipes, Nectria cinnabarina, Lopadostoma turgidum and Hypoxylon fragiforme , the last species showing the greatest resistance to drought. Water saturation of the substrate failed to initiate discharge in Xylosphaera polymorpha and X. longipes but did so in Hypoxylon fragiforme and Nectria cinnabarina possibly by capillary movement of water over the stromatic surfaces. Saturated atmospheres failed to initiate spore discharge in Lopadostoma turgidum and Hypoxylon fragiforme , but maintained high rates of discharge in Xylosphaera polymorpha and X. longipes .