Beneficial microorganisms

Research goal: The aim of this work was to develop a sustainable and innovative organic cultivation protocol, usable by local Italian companies, based on the use of microbial biostimulants (beneficial bacteria and fungi, arbuscular mycorrhizae and algae) able to improve the growth and quality production of the medicinal gel of Aloe vera. Materials and Methods: The experiments, started in December 2020, were conducted in the greenhouses of CREA-OF in Pescia (Pt), Tuscany, Italy (43°54′N 10°41′E) on Aloe vera (4 year old plants). The experimental groups were: i) group control, irrigated with water and substrate previously fertilized; ii) group with Effective microorganisms irrigated with water and substrate previously fertilized; iii) group with Trichoderma spp. irrigated with water and substrate previously fertilized; iv) group with arbuscular mycorrhizae irrigated with water and substrate previously fertilized; v) group with Ascophyllum nodosum irrigated with water and substrate previously fertilized. Results and Discussion: The experiment showed a significant improvement in agronomic parameters and physical, chemical and microbiological characteristics analysed on plants treated with microbial and algae-based biofertilizers. In particular, there was a significant improvement in the number of leaves per plant, new shoots, fresh vegetative weight, root and gel weight and the inflorescences number. On the leaves of the treated theses, there was a significant increase in leaf length and width and an improvement in gel pureness (optical density). There was also an increase in the number of microorganisms in the treated substrates and a lowering of the pH of the growing medium. The test also showed a lowering of the pH of the gel and a significant increase in soluble solids, sugars and fiber content in the theses inoculated with Effective microorganisms and a significant increase in fructose, glucose, proline and aloin. Conclusions: The trial confirms the significant results already obtained in other trials on vegetable, ornamental and Aloe plants by applying biofertilizing microorganisms and algae. The aim of this work was to develop an organic cultivation protocol based on microbial and algae treatments that can be used to improve the quality of Aloe vera plants. This protocol can be applied in general by those companies that are dedicated to the production of ornamental and fruit cacti and succulents and want to reduce or even eliminate the use of plant protection products

Soil is a complex ecosystem comprised of several and mutually interacting components, both abiotic (organo-mineral associations) and biotic (microbial and pedofaunal populations and plants), where a single parameter depends on other factors and affects the same and other factors, so that a network of influences among organisms coexists with the reciprocal actions between organisms and their environment. Therefore, it is difficult to undoubtedly determine what is the cause and what the effect within relationships between factors and processes. Soil is commonly studied through the evaluation and measurement of single parameters (e.g. the content of soil organic matter (SOM), microbial biomass, enzyme activities, pH, etc.), events (e.g. soil erosion, compaction, etc.) and processes (e.g. soil respiration, carbon fluxes, nitrification/denitrification, etc.), often carried out in laboratory conditions in order to limit the number of factors acting within the ecosystem under study, but missing the information about the global soil environment that way. In the last decade, several scientists have proposed and suggested the need for a holistic approach to soil ecosystems in different contexts. Recently, we have applied a sensing system developed in the last decades and capable of analysing complex mixtures of gases and volatiles (odours or aromas) in atmospheres, namely called electronic nose (EN). Typically, ENs are devices consisting of an array of differentially and partially specific, despite selective, sensors upon diverse coatings of sensitive films, i.e. interacting with single analytes of the same chemical class, despite not highly specific for a single substance, only, but showing also lower extent of cross-selectivity towards compounds of other chemical classes. ENs can be used in the classifications of odours by processing the collected responses of all sensors in the array through pattern recognition analyses, in order to obtain a chemical fingerprint (olfactory fingerprint) typical of the analysed air sample. Due to these features, we decided to apply such a sensing technology to the analyses of soil atmospheres, because several processes in soil, both abiotic and biotic, result in gas and/or volatile production and the dynamics of such releases may also be affected by several additional environmental factors, such as soil moisture, temperature, gas exchange rates with outer atmosphere, adsorption/desorption processes, etc. Then, the analysis of soil atmosphere may provide information about global soil conditions (e.g. soil quality and health), according to a holistic approach, where several factors are contemporarily taken into account. At the same time, the use of such a technology, if adequately trained on purpose, can supply information about a single or a pool of processes sharing similar features, which occur in soil over a certain period of time and mostly affecting soil atmosphere. According to these premises and hypotheses, we demonstrated that EN is an useful technology to measure soil microbial activity, through its correlation to specific metabolic activities occurring in soil (i.e. global and specific respiration and some enzyme activities), but also soil microbial biomass. On the basis of such evidences, we also were able to use this technology to assess the quality and health conditions of soil ecosystems in terms of metabolic indices previously identified, according to some metabolic parameters and biomass quantification of microbial populations. In other studies, we also applied EN technology, despite using a different set of sensors in the array, to analyse the atmosphere of soil ecosystems in order to assess their environmental conditions after contamination with polycyclic aromatic hydrocarbons (PAHs) (i.e. semivolatile - SVOCs - organic pollutants). In this case, EN technology resulted capable of distinguishing between contaminated and uncontaminated soils, according to the differences in a list of substances, occurring in the atmospheres of differently treated soils, which were identified through SPME-GC/MS analyses and then suggested to be responsible for the different classification. Analysing the EN responses, it was also possible to follow the degradation process of pollutants by resident microbial populations over time, on the basis of the contemporary decrease of contaminant and the increased release of CO2. Then, we suggest that EN technology may be usefully employed in the analyses of soil ecosystems in order to both supply information about global soil environment, according to the holistic approach, and about specific processes occurring therein. Furthermore, since EN technology resulted to be effective and successful in detecting processes in soil, in both natural and perturbed conditions, involving microbial populations, which are commonly considered as the most sensitive and responsive to soil environmental modifications, we suggest it might be reasonably employed in analyses concerning the assessment of soil quality and health. Consequently, such a technology may also be used to study several processes involving soil ecosystems, such as soil management practices, soil restoration, soil contamination and remediation, soil fertility, etc.