No abstract

Introducción. La lenta y asincrónica germinación de las semillas de café afecta la obtención de plántulas e incrementa los gastos asociados a la producción. La aplicación de rizobacterias promotoras del crecimiento vegetal (PGPRs) ha mostrado ser una alternativa ante esta problemática. Objetivo. Evaluar el efecto de la inoculación de rizobios en la germinación de dos cultivares de cafeto en condiciones controladas y productivas. Materiales y métodos. Durante enero y febrero del 2020, se desarrollaron dos experimentos en la Universidad de Oriente, Cuba, en el que se emplearon diez cepas de rizobios, provenientes de leguminosas y gramíneas, y dos cultivares de cafeto de importancia económica en Cuba: Coffea arabica cultivar (cv.) Isla 5-15 y Coffea canephora Pierre ex Froehner cultivar (cv.) Robusta. Los experimentos se realizaron uno en condiciones controladas, donde la germinación de las semillas se evaluó en placas Petri y otro donde se emplearon canteros pregerminadores. En ambos experimentos se empleó un diseño completamente aleatorizado y se realizó un análisis de varianza. Resultados. En condiciones controladas, la inoculación de las cepas Rpr11, Rpr2, 1-2, ICA8001 y Can3, incrementaron el porcentaje de germinación, la energía germinativa, el índice de germinación, el índice de velocidad de germinación y el índice de vigor. En los canteros pregerminadores, los inoculantes a base de las cepas Rpr2 y Rpr11 produjeron los mayores porcentajes de emergencia y de energía de germinación. Conclusión. Las cepas Rpr2 y Rpr11 de Rhizobium, incrementaron la germinación de las semillas de dos variedades de cafeto.

Rhizobia have been studied for the symbiosis that they establish with the roots of legumes. However, the colonization and promotion of growth in non-leguminous plants has also been demonstrated. The aim of this work was the biochemical and molecular identification of rhizosphere rhizobia present inthe rhizosphere of two commercial maize cultivars. Cultivableisolates were obtained in yeast-mannitol-agar (YMA) mediumfrom rhizospheric soil and the rhizoplane. The cultural (size,color, mucus, etc.), morphological, and staining (cell shape,response to staining and sporulation) characteristics weredetermined as well as isolate responses to eight biochemicaltests (acid-base production, citrate, oxidase, catalase, H2Sproduction, urease, gelatinase and the oxidative-fermentativeassay) that are valuable for rhizobia identification. The genuswas determined by 16S rDNA gene sequencing. We obtained 81total isolates of which 30.86% showed the cultural, morphological and staining characteristics expected for rhizobia and only 20% of these corresponded to the genus Rhizobium.

Introduction. The rice cultivar INCA LP-7 is one of the eleven principal cultivars in Cuba due to their high yield potential, salinity tolerance, and pathogens resistance. However, there are not reports about the isolation, identification, and characterization of bacteria associated to this cultivar that promote its growth. Objective. To select promising bacteria from the rhizosphere of the INCA LP-7 rice cultivar to promote the crop growth. Materials and methods. The investigation was carried out in 2015 and 2016 at the Instituto Nacional de Ciencias Agropecuarias, Cuba and Instituto de Investigaciones Biologicas Clemente Estable, Uruguay. The 16SrNA gene of bacteria associated with the INCA LP-7 rice cultivar was isolated and identified by sequencing. Characterization was performed as plant growth promoting bacteria and the effect of bacterial inoculation on rice growth was studied. Results. Eleven rizopheric bacteria were isolated from rice plants of the INCA LP-7cultivar. A phylogenetic analysis showed that for the first time in Cuba Pantoea, Acinetobacter, and Mitsuaria genera were reported associated with rice. Rhizobium and Enterobacter genera were also informed as rhizospheric bacteria of INCA LP-7 rice cultivar. Some isolates solubilize inorganic phosphates and potassium, produce siderophores and indolic compound, had exo-celulase and protease activity and formed biofilm. The inoculation of isolates belonging to Pantoea genus produced an increase in height, root length, and biomass of rice plants under greenhouse conditions. Conclusions. Pantoea sp. GG1 and Pantoea sp. GG2 were the most promising strains for the inoculation of the INCA LP-7 rice cultivar. This is the first report in Cuba that focuses on the characterization of the bacterial microbiota part associated to Cuban rice cultivar INCA LP-7 and reports bacteria of the Pantoea genus as crop growth promoters.

No abstract