Environmental factors influencing basidiospore discharge in Polyporus tomentosus

Abstract

Basidiospore discharge rates by sporophores of Polyporus tomentosus were highest at moderate temperatures (16–22 °C) and high relative humidity (85–100%), with either low light intensity or darkness. Discharge rates decreased abruptly when relative humidity was lowered to about 70% in continuous darkness and at constant temperature. Above 85%, fluctuations in relative humidity had little effect on spore discharge rates. In darkness and high relative humidity, discharge rates were positively correlated with temperatures between 5 and 23 °C. Illumination disrupted both these relationships. Under natural conditions, the periodicity of discharge rates was not correlated with the periodicities of light, relative humidity, or temperature, but appeared to be governed by the interaction of these three factors. Polyporus tomentosus discharged spores at a high rate on cloudy days when temperatures were moderate. Highest rates of discharge occurred in the evening and lowest rates occurred in the early morning.Basidiospore discharge rates did not appear to be related to other factors studied, for example, sporophore size, growth rate, and moisture content, or soil moisture and nutrient content. Sporophores required at least 180% moisture content to discharge spores at high rates.