Effect of culture filtrates of pathogenic and antagonistic fungi on seed germination of some economically important vegetables

The subject of present study was to check whether the pathogenic fungi that were associated with different rot diseases of fruits and vegetables and the antagonistic fungal species produce extracellular growth regulating substances. For this present study healthy seeds of four economically important crop plants, viz. Solanum lycopersicum, Brassica rapa, Raphanus sativus and Trigonella melongena were selected. The results showed that all the pathogenic fungi except Fusarium solani decrease the germination percentage of the all seeds. Solanum lycopersicum seed germination was completely inhibited by the culture filtrate of Trichothecium roseum and Alternaria alternata. Likewise, the culture filtrate of Penicillium expansum caused complete inhibition of the germination of Brassica rapa seeds. The culture filtrate of Fusarium solani was found to increase the germination percentage of all the seeds tested during the present study. Amongst the three Trichoderma spp., T. asperellum and T. harzianum culture filtrate effectively increases the seed germination percentage of all the seeds tested while the culture filtrate of T. viride have negative effect on the germination percentage of Solanum lycopersicum, Brassica rapa, and Raphanus sativus seeds. This stimulatory or inhibitory effect of the culture filtrates can be attributed to the presence of certain metabolites/substances that the test fungi have released in the medium. To identify the substances present and the nature of these substances further studies will be carried out.