Biostimulant derived from the fermentation of Inula viscosa (Inort) in the germination and growth of Amaranthus hypochondriacus

Research objective: This research aims to evaluate Inula's bio-stimulating potential in the form of macerate in water in the cultivation of Amaranthus hypochondriacus. This is to increase knowledge of this plant that commonly exhibits inhibitory characteristics towards the germination of various plants. Materials and Methods: The experiments started in May 2022 and were conducted in the greenhouses of CREA-OF in Pescia on Amaranthus hypochondriacus plants. On September 24, 2022, plant height, leaves number, leaves the surface area, vegetative weight, roots volume and length, the number of germinated seeds, average germination time, the number of microorganisms in the substrate, plant dead number and pH were determined. In addition, the SPAD index was measured on three leaves pinched from the bottom to the apex of the canopy of each plant (for a total of 90 measurements per treatment) and tissue mineral content was evaluated on collected dry matter (N, P, K, Ca, Mg, Fe and Na, Cl). Results and Discussion: The experiment showed that using Inula as a bio stimulant can significantly improve germination and growth and reduce mortality in Amaranthus hypochondriacus plants. In general, a significant increase in plant height and number of leaves, vegetative and root biomass was observed in plants treated with INORT, with differences depending on the percentage of product supplied to the plants. There was also a significant reduction in the mortality of plants treated with the biofertilizer product and increased microbial biomass. The trial also showed that the Inula biofertilizer could improve the chlorophyll content of the plant and increase the N, P, K, Ca, Fe, and Na content, while no differences were found for the parameters Mg and Cl. This test also shows biostimulant effects regarding seed germination and the average germination time reduction. This is interesting because Inula is usually mentioned for its inhibiting activity in seed germination, which probably depends on the transformation process. However, when macerated with microbial products, the inhibiting activity is nullified, and the fast-growing microorganisms utilize the organic products provided by this plant. Conclusions: In this experiment, further exciting and innovative aspects were highlighted in the use of this plant, given its already recognized importance from a medicinal, melliferous and biodiversity point of view. More experiments are underway to improve the protocol for using a biofertilizer based on Inula and microorganisms for horticulture for plant stimulation and defence