ASSESSMENT OF GARDENING GROWING MEDIA SUPPRESSIVENESS AGAINST RHIZOCTONIA DAMPING-OFF DISEASE

Abstract

In the present study the suppressive capability was assessed of four commercial peat- based growing media against Rhizoctonia solani on Lepidium sativum. For all organic media, 12 parameters were measured including phytotoxicity, enzymatic activities (glucanase, N- acetylglucosaminidase, chitobiosidase, endochitinase and hydrolysis of fluorescein diacetate), microbiological (culturable bacteria, pseudomonads and fungi) and chemical features (pH, EC and total protein). Three out of all media showed a significant disease suppression, while one was very conducive to disease development. Autoclaving growing media largely decreased or eliminated disease suppressiveness, suggesting that microbes play a vital role. In vitro tests showed a reduction in pathogen suppression when filter-sterilized extracts from the growing media were used. Moreover, disease suppressiveness were positively correlated with EC, supporting the hypothesis of a possible role of physical, other than biological factors, in R. solani control. Our results demonstrate that some peat-based growing media could be useful for the control of soil-borne pathogens.