Klever Ivan Granda Mora, Bettina Eichler-Loebermann, Yelenys Alvarado Capó, Roldán Torres-Gutiérrez:
Assessment of Ecuadorian Rhizobium Isolates under Field Conditions

KLEVER IVAN GRANDA MORA, BETTINA EICHLER-LOEBERMANN, YELENYS ALVARADO CAPÓ, ROLDÁN TORRES-GUTIÉRREZ
$^{1}$Universidad Nacional de Loja, Centro de Biotecnología , Ecuador
$^{2}$University of Rostock, Fac. of Agricultural and Environmental Sciences, Germany
$^{3}$Universidad Central Marta Abreu de Las Villas, Instituto de Biotecnologia de Las Plantas, Ecuador
$^{4}$National University of Loja, Centre of Biotechnology, Ecuador

The study aimed to determine the influence of Rhizobium isolates on phenotypic parameters and yield of common bean (Phaseolus vulgaris L.) genotypes under field conditions. A total of seven strains previously isolated, characterised and genetically identified from soils of Loja province were inoculated on seeds of Mantequilla and Rojo Calima genotypes, besides the inoculation of wild type strain Rhizobium etli CNPAF512. A treatment with nitrogen fertiliser (application of urea 60kg ha$^{-1}$) and a control without inoculation and fertilisation. Seeds were pelletized with the strains from the inoculants and planted in dry season on sandy loam soil. Nodulation parameters, plant biomass, yield components and agricultural yields were assessed. The results showed high capacity of nodule formation and biomass production by the treatments inoculated with isolates and wild type strain for both genotypes, compared with the native strains (control and mineral fertilisation treatments). R. miluonense (isolated from Catamayo), R. tropici (isolated from Saraguro) and wild type strain had a remarkable effect on these parameters. These treatments had similar behaviour for yield components, mainly in the number of pods and weight of grains per plant. The genotypic variability of the crop was higher for agricultural yields, where the best treats for Mantequilla genotype were obtained with R. tropici isolated and mineral fertilisation application, however no significat differences were observed among them. For Rojo Calima the wild type strain and R. miluonense showed the best results. This study validates the use of efficient interaction among Rhizobium species and bean genotypes to achieve yield increases through sustainable agricultural methods and to reduce the application of nitrogen fertiliser.

Keywords: Diazotrophic bacteria, inoculation, Phaseolus vulgaris, strains, yield

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Contact Address: Roldán Torres-Gutiérrez, National University of Loja, Centre of BiotechnologyAv. Pío Jaramillo ALvarado S/N. La Argelia., Loja, Ecuador, e-mail: roldantggmail.com