ABSTRACT
Plant growth has traditionally been considered to be affected by soil as a mineral substrate with no interaction with the crops apart from plant nutrient supply. Nowadays, the scientifi c community studies the soils as ecosystems in which soil microorganisms play key roles in any transformation (Miransari 2011). Amongst soil microorganisms, those that were initially comprehensively studied were the ones capable of producing
1Instituto de Medio Ambiente, Recursos Naturales y Biodiversidad. Universidad de León. Avenida de Portugal, 41. E24071 León. Spain. 2Facultad de Ciencias Agronómicas y Veterinarias. Universidad Autónoma de Santo Domingo. Dominican Republic. 3Fertiberia S.A. – Departamento de I+D+i. Spain. *Corresponding author: fernando.gonzalez@unileon.es
plant diseases and pests, thus reducing crop yields. In many cases, these studies focused on developing chemical products to overcome these pests and diseases with a detrimental effect on the soil microbial community as a whole. However, more recently there has been a shift in the research worldwide, considering soil microorganisms from a proactive point of view. This perspective leads to understanding the interactions between soil microorganisms and plants in terms of increasing the plant growth and health, thus directly or indirectly increasing agricultural productivity due to their relatedness with plant fi tness (Gutiérrez-Mañero and RamosSolano 2010). The following are among their most relevant benefi cial effects in agricultural soils: (1) recycling of soil nutrients available in organic form, with special relevance in the nitrogen cycle, (2) enhancing soil nutrient availability and consequently uptake by the plant, (3) alleviating abiotic stresses from the soil on plant growth and yield, (4) controlling pathogenic fungi or bacteria by means of a direct interaction between the benefi cial microorganism and the pathogen, or without direct interaction between the plant and the benefi cial microorganism, triggering a defending response on the plant against pathogens, (5) improving soil structure by producing different biochemicals (Emmerling et al. 2002, Böhme and Böhme 2006, Arzanesh et al. 2010, Gutiérrez-Mañero and Ramos-Solano 2010, Siddikee et al. 2011).
