Abstract
The present work was aimed at investigating the effects of a four strains consortium—Azospirillum brasilense, Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, and Burkholderia ambifaria—on crops of Allium cepa L. and its soil health. The bacterial consortium was inoculated on seeds of two different onion varieties; inoculated seeds and control ones (treated with autoclaved inoculum) were sown in open-field and followed until harvest. Plant growth development parameters, as well as soil physico-chemical and molecular profiles (DNA extraction and 16S community sequencing on the Mi-Seq Illumina platform), were investigated. The results showed a positive influence of bacterial application on plant growth, with increased plant height (+18%), total chlorophylls (+42%), crop yields (+13%), and bulbs dry matter (+3%) than the control. The differences between control and treated experimental conditions were also underlined in the bulb extracts in terms of total phenolic contents (+25%) and antioxidant activities (+20%). Soil fertility and microbial community structure and diversity were also positively affected by the bacterial inoculum. At harvest, the soil with the presence of the bacterial consortium showed an increase of total organic carbon, organic matter, and available P and higher concentrations of nutrients than control. The ecological indexes calculated on the molecular profiles showed that community diversity was positively affected by the bacterial treatment. The present work allowed to remark the effective use of plant growth-promoting bacteria as a valid fertilization strategy to improve yield in productive landscapes, whilst safeguarding soil biodiversity.
Highlights
One of the current concerns in agriculture is improving the sustainability of productive landscapes and at the same time, obtaining high production rates
Www.mdpi.com/journal/proceedings Proceedings 2020, 66, 20 work, we investigated the biostimulant effectiveness of seed inoculation with a bacterial consortium formed by Azospirillum brasilense Cd, Burkholderia ambifaria PHP7, Gluconacetobacter diazotrophicus
Onion seeds were treated with the bacterial consortium and dried overnight at room temperature
Summary
One of the current concerns in agriculture is improving the sustainability of productive landscapes and at the same time, obtaining high production rates. To achieve this goal, one of the promising and sustainable innovations could be the use of natural plant biostimulants [1]. Plant growth-promoting bacteria (PGPB) are considered sustainable biostimulant agents, effective in the presence of abiotic stresses factors [1]. Key traits for biostimulation are nitrogen fixation, nutrients solubilizing capabilities, and production of phytohormones [2]. PGPB formulations gained increasing attention, being highly regulated by European Union by Regulation EU 2019/1009.
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