Effectiveness of Arbuscular Mycorrhizal Fungal Isolates from the Land Uses of Amazon Region in Symbiosis with Cowpea

ABSTRACT Arbuscular mycorrhizal fungi provide several ecosystem services, including increase in plant growth and nutrition. The occurrence, richness, and structure of arbuscular mycorrhizal fungi communities are influenced by human activities, which may affect the functional benefits of these components of the soil biota. In this study, 13 arbuscular mycorrhizal fungi isolates originating from soils with different land uses in the Alto Solimões-Amazon region were evaluated regarding their effect on growth, nutrition, and cowpea yield in controlled conditions using two soils. Comparisons with reference isolates and a mixture of isolates were also performed. Fungal isolates exhibited a wide variability associated with colonization, sporulation, production of aboveground biomass, nitrogen and phosphorus uptake, and grain yield, indicating high functional diversity within and among fungal species. A generalized effect of isolates in promoting phosphorus uptake, increase in biomass, and cowpea yield was observed in both soils. The isolates of Glomus were the most efficient and are promising isolates for practical inoculation programs. No relationship was found between the origin of fungal isolate (i.e. land use) and their symbiotic performance in cowpea.

Caracterizacióneestructural de la materia orgánca de tres suelos provenientes del municipio de aquitania-boyacá, Cloombia / Strucural characcterization of organi matter of three soils from aquuitania-boyacá, Colomiaa / Caracteriação esstrutural da matéria orgânica de três sols provenientes do municipio de aquitania-boyacá, Colombia

La materia orgánica del suelo puede variar considerablemente en su estructura, composición y conformación, de acuerdo con el origen y la edad de los materiales que la constituyen. En la presente investigación se procedió a caracterizar, mediante el empleo de la espectroscopia infrarroja y la resonancia magnética nuclear en estado sólido, dos suelos inceptisoles (I01 y I02) y un histosol (H03) destinados al cultivo de cebolla larga, en el municipio de Aquitania-Boyacá, Colombia, a dos profundidades: 0 - 10 y 40 - 50 cm. Según los espectros infrarrojos, se detectó la presencia de grupos OH (debida posiblemente a fenoles, ácidos carboxílicos o alcoholes), grupos aromáticos y alifáticos. Los espectros de 13C-RMN en estado sólido con CPMAS evidenciaron el siguiente orden respecto a la cantidad de carbonos que conforman la materia orgánica del suelo: H03-0 =100 y H03 -40 = 88, I02-0 = 23 y I02-40 = 0, y finalmente I01-0 = 17 y I01-40 = 12, confirmándose la disminución de carbonos en la materia orgánica a través del perfil del suelo, y además se estableció que el carbón resonante en la región δ = 108-50 ppm de los espectros (N - y O-alquilos y acetales) dominó en toda la MOS obtenida; le siguió el carbón aromático (la cantidad de carbonos que conforman la materia orgánica del suelo: H03-0 =100 y H03 -40 = 88, I02-0 = 23 y I02-40 = 0, y finalmente I01-0 = 17 y I01-40 = 12, confirmándose la disminución de carbonos en la materia orgánica a través del perfil del suelo, y además se estableció que el carbón resonante en la región δ = 108-50 ppm de los espectros (N - y O-alquilos y acetales) dominó en toda la MOS obtenida; le siguió el carbón aromático (ó = 168-108 ppm) para los suelos I01-0 y H03-40, y el carbón alifático (δ = 0-50 ppm) para los suelos I01-40, I02-0 y H03-0. Finalmente, el carbón C = O (δ = 220-162 ppm) fue el menos dominante en la materia orgánica del suelo en todos los tres suelos caracterizados.

Generally, soil organic matters may differ in structure, composition and conformation according to their origin and age. In the present work structural composition of three soil organic matters, as determined by IR and solid-state CPMAS 13C-NMR spectroscopy of two Inceptisol soils (I01 and I02) and one Histosol soil (H03) from the Aquitania-Boyacâ town in Colombia are presented (in these soils farmers have grown large onion crops). Measurements were performed at two different depths 0 - 10 and 40 - 50 cm, respectively. According to the IR spectra the presence of OH-groups (from phenols, carboxylic acids and alcohols), aromatic and aliphatic groups were identified. The 13C NMR spectra revealed a decreasing amount of organic matter with increasing depth in the following relative order: H03-0 = 100 and H03-40 = 88, I02-0 = 23 and I02-40 = 0, and finally I01-0 = 17 and I01-40 = 12. The carbon peaks resonating in the ô = 108-50 ppm region of the spectra (N- and O-alkyls and acetals) dominated in almost all the extracted soils, with aromatic carbon peaks (δ = 168-108 ppm) showing the second most intense peaks for the samples I01-0 and H03-40. The aliphatic carbon (δ = 0-50 ppm) revealed the second most intense peaks in samples I01-40, I02-0 and H03-0. Finally, carbonyl carbon (δ = 220-162 ppm) contributed the smallest signal intensity in all the three soil samples.

A matéria orgânica do solo pode variar consideravelmente em sua estrutura, composição e conformação. Na presente pesquisa procedeu-se à caracterização mediante o emprego da espectroscopia de infravermelho e ressonância magnética nuclear no estado solido dos solos inseptisoles (101 e 102) e um histosol (H03) destinados ao cultivo de cebola no município de Aquitania -Boyacá, Colômbia a duas profundidades diferentes 0 - 10 e 40 - 50 cm, respectivamente. Encontrou-se de acordo aos espectros de infravermelho a presença de grupos OH (devido possivelmente a fenóis, ácidos carboxílicos o álcool), grupos aromáticos e alifáticos. Os espectros de 13C-RMN em estado solido com CPMAS evidenciarão o seguinte ordem de acordo à quantidade de carbonos que conformam a matéria orgânica do solo: H03-0 = 100 e H03-40 = 88, I02-0 = 23 e I02-40 = 0, e finalmente I01-0 = 17 e I01-40 = 12, sugerindo que a quantidade total de carbonos na matéria orgânica decresce a través do perfil do solo e além de mais, estabeleceu-se que o carbono ressonante na região δ = 108-50 ppm dos espectros (N- y O-alquilos e acetales) dominó em tudo a MOS extraída, seguiu-se o carbono aromático (δ = 168-108 ppm) para os solos I01-0 e H03-40; e o carbono alifático (δ = 0-50 ppm) para os solos I01-40, I02-0 e H03-0, finalmente o carbono carbonilo (δ = 220-162 ppm) foi o menos dominante na matéria orgânica do solo em todos os três solos caracterizados.