Selection of a growth promoter microbial consortium in onion seedlings under shade-house conditions

Abstract

The practice of producing more vigorous seedlings represents a competitive advantage at the time of transplanting a crop, and the use of combined biofertilizers are a sustainable ecological alternative. The objective of this research was to select a microbial consortium for the production of F1 2000 hybrid onion seedbeds under shade-house conditions. Five rhizobacterial strains of the genera Rhizobium (ME01 strain), Bradyrhizobium (Leu2A and YE1 strains), Ochrobactrum (ES1 strain) and Pseudomonas (Alf strain), which have shown favorable effects on pepper and lettuce seedlings. These rhizobacteria were inoculated in a mixed manner (microbial consortium) in onion as follows: Alf+ES1, ME01+ES1, ES1+Leu2A, Alf+Leu2A, YE1+ES1, ME01+Alf, YE1+Alf, ME01+YE1, YE1+Leu2A, ME01+Leu2A, using a soil from San Juan de Lagunillas-Mérida, Venezuela under shade-house conditions for 60 days. The following variables were determined: number of leaves, pseudostem base diameter, aerial and root length, aerial and root fresh and dry weight. Additionally, a CO2 assimilation curve under different light levels was carried out on the seedlings of the selected consortium to observe their photosynthetic response. The consortium ME01 + Leu2A (Rhizobium tropici + Bradyrhizobium japonicum) increased all studied variables, especially the pseudostem base diameter, essential for onion cultivation, and yielded higher seedlings CO2 assimilation rates. The use of this microbial consortium is recommended as an option for agricultural production under seedbed conditions.

Effect of a plant growth-promoting rhizobacteria consortium to promote growth in lettuce (Lactuca sativa L.) and chili pepper (Capsicum annuum L.)

“…La coexistencia de los miembros de la población va a depender de los cambios en las condiciones ambientales, no obstante, la vida en asociación permite una mayor resistencia a estos cambios y favorece la estabilidad de la población en el tiempo. En condiciones de estrés, como por ejemplo en periodos de limitación de nutrientes, existen grupos minoritarios dentro de la comunidad que tienen la capacidad metabólica de sostener la supervivencia del consorcio, estimulando la producción de polisacáridos o enzimas degradativas que permiten mejorar la disponibilidad de nutrientes y disponerlos para la comunidad (Blanco et al, 2021;Ochoa y Montoya, 2010). En esta investigación se observó una mejor respuesta cuando se utilizaron las bacterias C56 (A. xylosoxidans), JLB4 (A. pokkalii) y AV5 (B. pumilus) en conjunto como consorcio para estimular el índice relativo de clorofila (unidades SPAD) en plantas de lechuga, además de mostrar una tendencia favorable en el peso fresco aéreo de ambas plantas.…”