Bioeffectors have a direct or indirect effect on plant performance by influencing the functional implementation or activation of biological mechanisms, particularly those interfering with soil-plant-microbe interactions.
In contrast to conventional fertilizers and pesticides, the effectiveness of bioeffectors is not based on a substantial direct input of mineral plant nutrients, either in inorganic or organic forms.
*Products in use are:
** Microbial residues,
** Composting and fermentation products,
** Plant and algae extracts
*Bioeffector-preparations (bio-agents) as ready-formulated products are applied:
** with the purpose of stimulating plant growth (bio-stimulants),
** to improve plant nutrient acquisition (bio-fertilizers),
** to protect plants from pathogens and pests (bio-control agents)
** or generally to advance cropping efficiency; they can contain one or more bio-effectors along with other substances”
*Well established bioeffectors with documented positive results in the field level are:
** Rhizobia strains for soil or seed inoculation as a prerequisite for symbiotic N2-fixation when establishing new legume species or varieties.
** positive effects of mycorrhiza inoculation for soils with a (temporarily) low potential for natural root mycorrhization.
** sufficient mycorrhization enhances nutrient (P) and water uptake and increases resistance to pathogenic fungi.
*Further mechanisms for the positive impact of bioeffectors on plant growth have postulated, promising a high potential for resource preservation due to reduction of fertiliser and pesticide use:
** Active nutrient mobilisation by exudation of acids and carboxylates (e.g. P-mobilisation),
** exudation of micro-nutrient mobilising siderophores/chelates (e.g. Fe),
** reduction of trace elements from less soluble oxidised to highly soluble reduced forms (e.g. Fe to Fe, Mn to Mn),
** associative/non-symbiotic N-fixation, protective antagonism to plant pathogens,
** enhancement of mycorrhizal infection and growth, and stimulating hormonal effects.