Microorganisms and algae (GEA soil) use in the cultivation of onion (Allium cepa L.) and garlic (Allium sativum L.)

Research objective: This research aims to evaluate the biostimulant potential of an innovative microbial product on the development of onion (Allium cepa L.) and garlic (Allium sativum L.) bulbs and roots under controlled conditions

Materials and Methods: The experiments began in early July 2022 (mean temperature 22.5 °C), were carried out price experimental greenhouses of the CREA-OF of Pescia (Pt), Tuscany, on bulbs of onion (cv “Rossa di Tropea”) and garlic (cv “Bianco Polesano”). The bulbs were placed in pots ø 14 cm; 40 bulbs for thesis divided into replicas of 20 bulbs each, for all onion and garlic.

The three experimental theses in cultivation were: i) group control irrigated with water and previously fertilised substrate; biofertiliser Ecklonia maxima irrigated with water and previously fertilised substrate; Gea soil (GEA) group irrigated with water and substrate previously fertilised.

On 26 January 2024, bulbs weight, bulb diameter, roots weight, number of microorganisms were determined. In addition, the mortality of the bulbs in the nursery was assessed.

Results and Discussion: The experiment showed that the use of biostimulants based on microorganisms and algae can significantly improve the size, weight and root growth of onion and garlic bulbs. In particular, the GEA soil thesis showed a significant increase in bulb length, weight and root growth compared to Ecklonia maxima and the untreated control thesis. There was also a significant increase in microbial colonisation of the substrate with GEA soil, a very interesting aspect that certainly had an effect on the growth of onion and garlic bulbs. The micro-organisms also by direct stimulation on the plants or by colonisation of the substrate significantly reduced bulb mortality in Gea soil, compared to BIOAL and the control. In recent years, horticulture has had to face the challenge of economic and environmental sustainability, reducing fertiliser use while adopting strategies to increase water use efficiency. Numerous forecasting models have shown that in the next 30 years many production areas could become semi-arid and among these is the Mediterranean basin, where many horticultural crops are grown. Increasing water use efficiency in this context appears essential for the development of sustainable horticulture. Many microorganisms or fungi can promote the plant's utilisation of nutrients and water in the soil. There are numerous strains of bacteria that promote root growth and are classified according to whether they act at the rhizosphere and rhizoplane level.

Conclusions: Microbial biostimulants can be a valuable strategy to mitigate environmental stresses that have been emphasised by climate change in recent years. Microbial biostimulants, by increasing the biodiversity of the agro-ecosystem and creating long-lasting symbiotic relationships with the plant, are, in fact, a sustainable and effective solution to prevent the reduction in productivity caused by abiotic stresses and to optimise the use efficiency of human inputs in the agrarian ecosystem.