Suleiman, M.N., Emua, S.A. and Ayodele, S.M.
Growth and physiological studies on Pythium aphanidermatum was carried out. The mycelia of the fungus grew satisfactorily on the entire agar media used. Potato Dextrose Agar (PDA) was found to be the best medium in term of mycelial extension, mycelial density and sporangia production compared to Malt extract and Czapeck-Dox agar. The best mycelial growth of Pythium aphanidermatum was on potato dextrose agar (PDA). The optimum temperature for the mycelial growth of the fungus was observed at 30oC and sporangia production was favoured at 25oC. The results of investigations on the effect of temperature on the sporangia production of P. aphanidermatum showed that sporangia production and germination was best at 30oC. Sporangia production was poor at 25oC and 35oC. There was no sporangia production at 20oC and 40oC. And on the effect of relative humidity on mycelia growth and sporangia formation, the result showed that P. aphanidermatum grew and produced sporangia much more profusely at high relative humidity than at low relative humidity level when incubated at 27oC. The highest rate of sporangia production (15.33×104 sporangia) occurred at 100% relative humidity, while no sporangia were observed to occur at relative humidity levels lower than 32.5%. Amongst the carbon sources supplemented, starch was best utilized with the highest mycelia dry weight of 0.74g /30ml media but glucose favoured sporangia production. Urea was most utilized among the nitrogen sources with the highest number of sporangia production.
