Identification and characterization of native rhizobia from three mungbean varieties

Aims@#Native rhizobia from root nodules of mungbean could reduce atmospheric nitrogen to ammonia for assimilation. The objective of this study was to find the best native rhizobium from mungbean. @*Methodology and results@#Three rhizobia isolates from three mungbean varieties (Maejo 3, Khampangsan 2 and Chainat 72) were collected from 10 undamaged fresh nodules at Prince Chakrabandh Pensiri Center for Plant Development, Saraburi Province, Thailand in 2016. 16S rDNA analysis identified the three rhizobia isolates as Bradyrhizobium sp. (SB1), Bradyrhizobium elkanii (SB2) and Rhizobium sp. (SB3). All the isolates could grow well in yeast mannitol agar (YMA) at pH 7, and all isolates could tolerate up to 35 °C, with isolate SB3 tolerate up to 45 °C. Isolate SB2 produced the highest amount of indole acetic acid (IAA; 8.37 mg/L) and had the highest phosphate solubilization index (7.60 SI). In a Leonard jar trial, inoculation with isolate SB2 resulted in the highest shoot fresh and dry biomass of mungbean host. Further, the mungbean inoculated with SB2 had the highest number of root nodules, nodule fresh dry weight, chlorophyll content index, and shoot and root nitrogen contents. @*Conclusion, significance and impact of study@#This study suggested that the strain SB2 (B. elkanii) is a suitable bioinoculant to improve mungbean growth and yield.

Infectividad y efectividad de rizobios aislados de suelos de la Costa Caribe colombiana en Vigna unguiculata / Infectivity and effectiveness of isolated rhizobia from colombian Caribbean Soils in Vigna unguiculata

Es el primer estudio en Colombia que abarca una evaluación de rizobios nativos asociados a frijol Caupí (Vigna unguiculata L. Walp.) en los departamentos del Cesar y la Guajira. En esta investigación, se demostró que la utilización de aislamientos de rizobios nativos aislados a partir de nódulos, mejoraron el desarrollo del frijol Caupí (Vigna unguiculata L. Walp.), siendo estas bacterias más eficientes que los tratamientos químicos y absolutos (sin inóculo ni fertilización) y que las cepas inducidas mejorando además, la fijación biológica de nitrógeno y la tasa fotosintética. Como aportes del estudio, se determinó que en condiciones de invernadero la fertilización biológica fue más eficiente que la química y que, de acuerdo a los resultados obtenidos de las diferentes variables agronómicas evaluadas, esto podría influir positivamente en los rendimientos nutricionales del cultivo, base alimentaria de los sistemas ganaderos de estas regiones del país y fuente alimenticia de la comunidad indígena y de bajos recursos económicos.

This is the first study in Colombia which covers an evaluation of native rhizobium associated to the Caupí bean (Vigna unguiculata L. Walp.) in the departaments of Cesar and Guajira. In this research it was demonstrated that the use of native rhizobium isolated from nodes, improved the development of the Caupí bean (Vigna unguiculata L. Walp.), being this bacteria more efficient than the chemical and absolute treatments (without inoculum and fertilization) also improving the biological nitrogen fixation and the photosynthetic rate. As contribution of the study, it was determined that in greenhouse conditions and according to the results obtained from differents measured agronomic variables, this could influence positively in the nutritional performance of the crop, basis of food of the cattle system of this regions of the country and the food source of the indigenous community of low economic income.