Selección de rizobios ácido-toelrantes para la inoculación de alfalfa (Medicago Sativa L.) en suelos ácidos
Loading...
Date
2025
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad de Concepción
Abstract
Los rizobios son bacterias fijadoras de nitrógeno que se asocian simbióticamente a plantas de la familia leguminosa. Estos pueden variar en su tolerancia a distintos pH por lo que su efectividad puede verse afectada en suelos ácidos. El objetivo de esta investigación fue evaluar la capacidad de cepas de Sinorhizobium meliloti y Rhizobium spp. aislados desde alfalfa en diferentes condiciones edafoclimáticas de Chile, de desarrollarse a distintos niveles de pH y caracterizar a aquellas capaces de crecer a pH ácido. Se aislaron rizobios de 31 plantas de alfalfa, desde cinco puntos diferentes en Cañete, Región del Bio-Bío, y el análisis de su huella genética determinó que correspondían a cinco cepas bacterianas genéticamente distintas
entre sí, descartándose ocho aislados que tuvieron un patrón genético idéntico. La evaluación in vitro de estas cepas más la colección de rizobios asociados a alfalfa en distintas regiones de Chile, mostró que el crecimiento de colonias tendió a ser más lento a medida que el pH era más bajo y la mayoría de las cepas no logró formar colonias a pH 4 y 5, a excepción de las cepas bacterianas provenientes de la zona de Cañete, algunas de las cuales tuvieron un crecimiento abundante a pH 4. Las cepas de Sinorhizobium meliloti y Rhizobium spp aislados desde alfalfa en diferentes lugares de Chile variaron en su tolerancia a pH ácido. Existe una correlación significativa entre el pH de suelo de origen de la bacteria y su tolerancia a pH bajo.
Rhizobia are nitrogen-fixing bacteria that form a symbiotic association with plants from the family Fabaceae. These bacteria can vary in their tolerance to different pH levels, so their effectiveness may be affected in acidic soils. The objective of this research was to evaluate the ability of Sinorhizobium meliloti and Rhizobium spp. strains, isolated from alfalfa under different edaphoclimatic conditions in Chile, to grow at various pH levels and to characterize those capable of growing at acidic pH. Rhizobia were isolated from 31 alfalfa plants collected from five different locations in Cañete, Bio-Bío Region. The analysis of their genetic fingerprint determined that they belonged to five genetically distinct bacterial strains, with eight isolates being discarded due to identical genetic patterns. The in vitro evaluation of these strains plus the rhizobial collection from alfalfa from different regions of Chile, showed that colony growth was slower as the pH decreased. Most strains failed to form colonies at pH 4 and 5, except for strains from the Cañete area, some of which showed abundant growth at pH 4. The Sinorhizobium meliloti and Rhizobium spp. strains isolated from alfalfa in different locations in Chile varied in their tolerance to acidic pH. A significant correlation was found between the soil pH of the bacterial origin and its tolerance to low pH.
Rhizobia are nitrogen-fixing bacteria that form a symbiotic association with plants from the family Fabaceae. These bacteria can vary in their tolerance to different pH levels, so their effectiveness may be affected in acidic soils. The objective of this research was to evaluate the ability of Sinorhizobium meliloti and Rhizobium spp. strains, isolated from alfalfa under different edaphoclimatic conditions in Chile, to grow at various pH levels and to characterize those capable of growing at acidic pH. Rhizobia were isolated from 31 alfalfa plants collected from five different locations in Cañete, Bio-Bío Region. The analysis of their genetic fingerprint determined that they belonged to five genetically distinct bacterial strains, with eight isolates being discarded due to identical genetic patterns. The in vitro evaluation of these strains plus the rhizobial collection from alfalfa from different regions of Chile, showed that colony growth was slower as the pH decreased. Most strains failed to form colonies at pH 4 and 5, except for strains from the Cañete area, some of which showed abundant growth at pH 4. The Sinorhizobium meliloti and Rhizobium spp. strains isolated from alfalfa in different locations in Chile varied in their tolerance to acidic pH. A significant correlation was found between the soil pH of the bacterial origin and its tolerance to low pH.
Description
Tesis presentada para optar al título de Ingeniero Agrónomo
Keywords
Rizobios, Alfalfa - Chile, Acidez del Suelo