Evaluación de la inoculación con microorganismos fijadores de nitrógeno asimbióticos aislados de la rizósfera de Pinus patula en Colombia

Abstract

SUMMARYThe effects on different vegetal parameters of asymbiotic nitrogen-fixing bacteria isolated from the rhizosphere of Pinus patula were studied under greenhouse conditions, in experiments designed for statistical analysis using these forest specie seedlings. This research also examined the interactions of ectomycorrhizal fungus Suillus luteus and the microorganism isolates in P. patula, as well as the nitrogenase activity in these bacteria by acetylene reduction assay. The free nitrogen-fixing bacteria Azotobacter chroococcum, Bacillus macerans, Enterobacter agglomerans and Pseudomonas sp., were isolated of the rhizosphere of P. patula. Their maximum acetylene-reducing values were 120, 18.7, 100, 120 nmol ethylene/tube respectively. Results showed that the best plant growth and nitrogen uptake in the in vivo test in P. patula with these microorganisms and S. luteus were observed with A. chroococcum. According to the longitudinal root cuts in the treatments using S. luteus with A. chroococcum, B. macerans, E. agglomerans, or Pseudomonas sp., the fungus with the agglutinated bacteria was showed around the mycorrhizal root surface only in the S. luteus and B. macerans treatment, but the mycorrhizal infection percentage was low. The inoculation with nitrogen fixing bacteria stimulated longitudinal growth and nitrogenous nutrition of P. patula.Key words: asymbiotic, ectomycorrhizas, nitrogen-fixation. RESUMENEl efecto de bacterias fijadoras de nitrógeno asimbióticas aisladas de la rizósfera de Pinus patula sobre diferentes parámetros vegetales fue estudiado bajo condiciones de invernadero, usando plántulas de esta especie forestal. Esta investigación también examinó la interacción entre el hongo ectomicorrízico Suillus luteus y los microorganismos aislados en P. patula, así como la actividad de la nitrogenasa por el ensayo de reducción de acetileno. De la rizósfera de P. patula se aislaron las bacterias fijadoras libres de nitrógeno Azotobacter chroococcum, Bacillus macerans, Enterobacter agglomerans y Pseudomonas sp. Los valores máximos de reducción de acetileno presentados por estas bacterias fueron 120, 18, 7, 100, 120 nmol etileno/tubo, respectivamente. Los resultados en el ensayo in vivo de P. patula con estos microorganismos y S. luteus mostraron que el mejor crecimiento de las plantas y la captación de nitrógeno se observaron con A. chroococcum. Al observar los cortes longitudinales de raíz de los tratamientos usando S. luteus con las diferentes bacterias (A. chroococcum, B. macerans, E. agglomerans y Pseudomonas sp.) sólo el tratamiento con S. luteus y B. macerans presentó el hongo con bacterias aglutinadas alrededor de la superficie de la raíz micorrizada, pero el porcentaje de micorrización fue bajo. La inoculación con bacterias fijadoras de nitrógeno estimuló el crecimiento longitudinal y la nutrición nitrogenada de P. patula.Palabras clave: asimbiótico, ectomicorrizas, fijación de nitrógeno.

Assessment of the Effectiveness of Ectomycorrhizal Inocula to Promote Growth and Root Ectomycorrhizal Colonization inPinus patulaSeedlings Using the Most Probable Number Technique

“…Plant height (cm) Shoot dry weight (g) Root collar diameter (mm) Ectomycorrhizal colonization (%) 3.9 (0.7) 0.7 (0.1) 1. dependent on root ectomycorrhizal colonization, as reported for species such as P. pinaster [8], P. pinea [21], and P. thunbergii [22], and the values for ectomycorrhizal colonization are comparable with those reported [19,20]. The differences in root ectomycorrhizal colonization levels seem to be in turn determined by the EPD level of the inocula tested (ES inoculum = 34 per g and EM inoculum = 156 per g).…”

“…The results clearly demonstrated that both factors inoculum type and dilution level had significant effects on P. patula seedling growth. The treatments with undiluted inocula were most effective for promoting seedling growth; nevertheless, the most significant growth was still lower than that reported for other species (P. maximinoii, P. oocarpa, and P. tecunumanii) [19,20].…”

Plant Growth Response ofPinus patulaandP. maximinoiSeedlings at Nursery to Three Types of Ectomycorrhizal Inocula

“…Surprisingly, in P. patula the foliar P concentration was not signi cantly a ected by dose and inoculum type, whereas in P. maximinoi there were interactive e ects. is may be due to a dilution e ect that masked the increase in seedling P uptake or intrinsic di erences in growth rates between both species [4,41,42]. Note that P. maximinoi exhibited higher growth values than P. patula, which perhaps limited the plant P uptake in the latter.…”

Scientometric analysis of Colombian research on bio-inoculants for agricultural production

“…In the case of non-leguminous plants, there is no symbiotic relation, therefore the plant is inoculate with free-living N2 fixing bacteria, such as Azotobacter and Azospirillium. These were inoculated in patula pine (Orozco & Martínez, 2009), pastures (Garrido et al 2010, Cárdenas et al 2010, Cárdenas et al 2014), stevia (Borda et al 2011), vegetables (Jiménez et al 2011, eucalyptus (Obando et al 2010, Rojas et al 2013, and maize (Rojas et al 2012). In high efficiency plants having photosynthesis (C4 plants) sugar cane and corn, successful results have been obtained when inoculated into the rhizosphere.…”