Phytotoxic and herbicidal activities of Aspergillus and Penicillium species isolated from rhizosphere and soil.

Two fungi, one isolated from the rhizosphere of Mentha piperita and the other isolated from the top soil (20 cm) of the agricultural farm of the University of Agriculture Peshawar, Pakistan. The rhizospheric fungus was identified as Aspergillus and Penicillium as soil born. The dried crude extracts of Aspergillus and Penicillium species were screened for phytotoxic bioassay and herbicidal activities (against Lemna minor and the weed Silybum marianum L., respectively) in order to evaluate the agrochemical importance of the extracts. Different dose concentrations (10, 100 and 1000 μgmL) of the ethyl acetate and n-Hexane fraction of both the species were tested against Lemna minor and seeds of Silybum marianum L. A dose concentration of 1000 μgmL of ethyl acetate extract and n-Hexane fraction of Aspergillus species inhibited the growth of Lemna minor by 65 and 85%, respectively; while the same dose concentration of ethyl acetate extract and nHexane fraction of Penicillium species inhibited the growth of Lemna minor by 56.66 and 30%, respectively. In addition, the same dose concentrations of the crude extract from both the species completely inhibited the germination of the seeds of Silybum marianum L. The results showed that extract of both fungi has potential agrochemical constituents which might inhibit the growth of Silybum marianum L. and Lemna minor. The results showed potent herbicidal activity against the test weed and therefore is suggested for further isolation and purification work of the active component(s).