Microbial bio stimulant obtained from cactus and succulent plants for rooting and growth of the castello hybrid rose (Attilio Ragionieri)

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 and growth of Attilio Ragionieri rose. Materials and Methods: The experiments, which began in February 2022, were conducted in the CREA-OF greenhouses in Pescia (PT), Tuscany, on cuttings obtained from a mother plant of the Attilio Ragionieri rose. Experimentation with the use of microbial consortia selected from cactus and succulent roots was carried out both to assess possible differences in rooting of cuttings and to highlight improvements in plant cultivation and growth. After 3 months from the start of the trial in May 2022, the following parameters were evaluated on the plants: number of cuttings rooted, average rooting speed, dead cuttings. After 5 months of cultivation from the time of transplanting, the following parameters were analysed on the plants and in the substrate in October 2022: plant height, number of leaves, leaf area, vegetative weight, roots volume and length, number of microorganisms in the substrate, number of dead plants, pH substrate value and SPAD index. Results and Discussion: The experiment showed that the use of microorganisms introduced in the rooting medium of rose cuttings can significantly increase the percentage of rooted cuttings, reduce the rooting time and mortality of the cuttings. Furthermore, once rooted, the cuttings colonised by the microorganisms grow better, showing an increase in height, number of leaves, vegetative and root weight, increasing root length, leaf area and chlorophyll content. A very interesting aspect was also the increase in microbial biomass in the treated theses, particularly in the thesis inoculated with microorganisms obtained from cactus and succulent roots. Interestingly, there are no references in the literature on the use of these microbial selections evaluated for plant rooting, stimulation and resistance, which is why this work appears to be of particular importance. Plants living in our latitudes may be better able to adapt to climate change in the future if microorganisms from extreme environments are used. Conclusions: Microbial biofertilisers can maintain low crop productivity and increase resistance to biotic and abiotic stresses, and in particular can improve fertiliser utilisation. The development of innovative protocols for the rooting and cultivation of old, often forgotten roses by exploiting microbial consortia that have not yet been tested seems to be a very important aspect for the recovery of important plants that might become extinct. Further research is currently underway on other ornamental species of historical and religious interest.