Comparative growth of three Paecilomyces species on natural media and the possible pathological effects of their cultural metabolites on seed germination and radicle development of six economic crops in Ghana

Abstract

Three Paecilomyces species from Cabi Science (UK) and P. carneus GHL 001 isolated from a local shrimps (Ghana) were tested for their radial growth characteristics on four different natural media, at temperatures of 15 °C, 18 °C, 20 °C and 25 °C using the culture plate radial method. The ability of culture metabolites of the test fungi raised in Yam Dextrose and Potato Dextrose Broths were tested on the germination capacity of six economic crops, using the conventional seed blotter test method. Radial growth of the fungal species showed similar growth pattern with optimum growth at 25 °C in most instances. The local P. carneus GH001 grew better and faster on all the media tested than P. carneus IMI133119 from the UK, underscoring the influence of environmental adaptation to physiological performance. The varietal differences in the response of the germinating seeds to the toxic metabolites can be ranked in decreasing order as follows: P. carneus IMI GHL 001 ˃ P. carneus IMI 133119 ˃ P. varioti IMI 40025 ˃ P. puntoni IMI 58415. To the best of our knowledge, this is the first report on the metabolites of P. carneus, P. puntoni and P. varioti adversely having pathological influence on germination and radicle development of cowpea, groundnut, soybean, okra, sorghum and cucumber in Ghana. Since these Paecilomyces species are used in some agricultural jurisdictions as entomopathogens for biocontrol of pests and diseases, environmental impact assessment is encouraged with the view of monitoring the soil bank for conidia of Paecilomyces which may affect the performance of crops in the field.