Growth-promoting microorganisms in the root stimulation of Celtis Australis (Bagolaro) and in the control of Ganoderma applanatum and Laetiporus sulphureus

Research objective: The aim of this research was to evaluate the stimulating potential of new microbial consortia obtained from the root systems of cacti and succulents in the rooting of Celtis australis and in the protection of certain fungal pathogens of this plant. The possible interaction between plants and substrate microorganisms in plant mortality was evaluated. Materials and Methods: The experiments, which began in January 2024, were conducted in the CREA-OF greenhouses in Pescia, Tuscany, Italy on 2-year-old Celtis australis plants obtained from seed. The seedlings were potted 16, 5 plants for 3 replications for each experimental thesis, for a total of 15 plants each. After 5 months of cultivation since transplanting, the following plant and substrate parameters were analysed in June 2024: plant height, number of leaves, leaf area, vegetative weight, root volume and length, number of microorganisms in the substrate, pH of the substrate and number of dead plants for Ganoderma applanatum and Laetiporus sulphureus. In addition, the SPAD index was measured on three pinched leaves from the base to the apex of the crown of each plant. Results and Discussion: The experiment showed that the use of microorganisms introduced into the rooting substrate of Celtis australis plants can significantly increase vegetative and root growth, increase plant height and the number of leaves. There was also a significant increase in leaf area, root length and chlorophyll content as demonstrated by SPAD analysis. A very interesting aspect was also the increase in microbial biomass in the treated theses, particularly in the thesis (SYB), an inoculum of microorganisms obtained from the roots of cacti and succulents. The treatments with micro-organisms in particular (SYB) resulted in a significant reduction in plant mortality caused by the pathogenic fungi Ganoderma applanatum and Laetiporus sulphurous. Conclusions: In light of possible climate change, it is also important to evaluate new microbial selections from plants that live in extreme environments, such as cacti and succulents. Plant productivity can be maintained while reducing environmental impact and increasing resistance to biotic and abiotic stresses with microbial biofertilisers. In order to improve and speed up the growth of nursery plants, especially trees to be placed in the environment, it seems very important to develop innovative protocols to increase their rooting and vegetative growth.