Three xerophilic fungal species, Paecilomyces carneus, P. puntoni, and P. varioti were for the first time isolated from two newly-developed Ghanaian maize varieties; Abeleehi and Obaatanpa. The fungal species were isolated under varying ambient humidity of 55-65% in both grain varieties. The culture filtrate of the Paecilomyces species raised in Maize Meal broth prepared from either Abeleehi or Obaatanpa and Potato-Dextrose broth were tested on the germination capacity of grains of Abeleehi and Obaatanpa using the blotter test method. The physiological condition for optimal growth of the Paecilomyces species were tested on Czapek-Dox Agar, Maize Meal Agar (Abeleehi), Maize Meal Agar (Obaatanpa), Malt Extract Agar and Potato Dextrose Agar at  (18, 30, 35, and 40) ^oC. Radial growth of the Paecilomyces species was influenced  by media and temperature of incubation. The optimum growth of P. carneus on all agar media used was obtained at a 30^oC, a temperature of 40^oC was clearly unsuitable for growth of P. carneus as the fungus remained static at this temperature after 2-4 days growth. The best radial growth of P. puntoni was obtained between 30-35^oC. Growth at 18^oC initially lagged behind those kept at 30^oC but approximated their growth rate after 6 days incubation period. There was no statistical difference (P ≤ 0.05) between growth of P. puntoni in all the media tested. Temperature of 35^oC and 40^oC depressed radial growth of P. varioti in all media tested. The best temperature for growth of P. varioti was 30^oC. Temperature 18^oC was almost as suitable as 30^oC for P. varioti. Radial growth of P. varioti was slowest on Potato Dextrose agar as compared to the other media tested. Percentage germination of the maize grains was depressed by 10 -75% by the undiluted, 2, 4, and 8 days old culture filtrate of the three Paecilomyces species. However, there were varietal differences in the response of the germinating maize grains to the active ingredient in the culture metabolites of the three Paecilomyces species. The inhibitory effect was gradually removed with increasing dilution. The same culture filtrate severely depressed length of emerging radicles of the two maize varieties by 40 - 90% at the highest concentration applied. The reduction in radicle length was severer on Abeleehi variety as compared to Obaatanpa.

Download this article as