Rhizoctonia solani is one of the phytopathogens that attack tomatoes cultivated under greenhouse conditions, causing root and crown rot. R. solani is controlled using methyl bromide, a fumigant known for its high toxicity and its degradative effect on the ozone layer. Fungi of the genus Trichoderma are important biocontrol agents (BCAs) of several soil borne phytopathogens. Trichoderma use different mechanisms for the control of phytopathogens which include mycoparasitism, competition for space and nutrients, secretion of antibiotics and fungal cell wall degrading. In addition, Trichoderma could have a stimulatory effect on plant growth as a result of modification of soil conditions. The biocontrol by fungal species of the Trichoderma genre, of root and crown rot caused by R. solani, are being used as an alternative to chemical fungicides. Phytopathogenic fungi produce significant crop losses annually and to limit their degree of attack we opted for biological control. Although the biological control of plants has been approached by many researchers from different countries, it is important to discover new wild strains native to Romania to combat phytopathogenic fungi and to stimulate plant growth and development. The new wild strains of microorganisms - bacteria and fungi isolated in this experiment have proven their ability to stimulate plant development and combat phytopathogenic fungi that cause seedlings to fall on tomatoes. In vitro experiments were carried out at the laboratory of Ecology and Microbiology at the Faculty of Land Reclamation and Environmental Engineering, U.S.A.M.V. Bucharest starting with March 2020 after soil sampling in Băneasa Forest. In vivo experiments were carried out in a vegetable garden in the village of Tamași, Corbeanca commune, Ilfov county since April 2020. The aim of the experiments was to obtaining microorganisms beneficial to plant development and protection and to highlight the capacity of microorganisms - bacteria and fungi - from forest soil to control phytopathogenic fungus in the complex, causing plant drop at tomatoes, which are frequently occurring in greenhouses and fields. Our research will continue in the direction of rigorous characterization of new wild strains of microorganisms isolated both at the genetic molecular level and of the mechanisms of action in the relationships of plant microorganisms and bioactive compounds secreted by these wild strains of microorganisms. Also, after characterizing the new microbial strains, we aim to obtain on their basis at laboratory and pilot scale growth stimulators and fungicides. For this we will carry out studies to optimize the conditions for growing microbial biomass, to obtain biologically active substances and to formulate ecological fungicides and growth stimulants for plants.

Rhizoctonia solani, tomatoes, biological control, wild strains of soil bacteria and fungi

biology

Presentation: oral