Ceferino R. Flores, Martín J. Castro Rojas, Rosario Vitoria, Noelia Rueda, Rosa E. Rueda, Alejandro Ismael y Claudio Ortiz
Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria de Cultivos Tropicales Yuto; Argentina
Abstract
Horticulture is mainly based on the use of high-yielding varieties or hybrids associated with the application of chemical synthesis inputs. In these circumstances, the biological and ecological processes that regulate many functions of these systems have been disregarded, resulting in natural resources deterioration and a constant increase in dependence on external inputs. From a physical point of view, the incorporation of organic matter (OM) promotes the formation of soil aggregates, prevents erosion, improves aeration in clay soils, increasing water retention capacity in sandy soils, maintaining a constant temperature and generating a better environment for the development of roots and micro-organisms. OM has negative electrical charges, so attracts positively charged nutrients such as calcium, magnesium and potassium (increasing the CEC of the soil). OM also associates with micronutrients such as iron, magnesium, zinc and copper, forming stable chelates that are available to plants. Finally, OM is food and energy for living organisms in the soil, mostly microorganisms. In the crop, proper management including fertilisation plans according to the estimated yields and irrigation according to the requirements, allow an optimal metabolic development of the crop; under these conditions, root exudates are produced that promote the emergence of beneficial microbial populations. The use of “Plant Growth Promoting Microorganisms” (PGPM) and “Biological Control” (BC) agents are part of a set of practices aimed at recovering the microbial diversity of the soil. PGPMs promote plant growth, through the fixation of atmospheric nitrogen, the production of phytohormones, and also increase the availability of phosphorus and nitrogen in an assimilable form for the plant. At the same time, they generate the degradation of ethylene synthesis precursors. BC suppress the expression of pathogenic microorganisms by secretion of antimicrobial metabolites, competition for iron, their increased ability to colonise the rhizosphere, preventing the germination of fungal spores and inactivating toxins. Therefore, the interaction between the incorporation of OM to the soil, adequate crop management practices and the incorporation of PGPM and CB microorganisms lead to the expression of yield potential, improving the crop performance in face of adverse biotic and abiotic factors.
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