Initial development of upland rice plants inoculated with the MAY12 strain of Azospirillum spp / Desenvolvimento inicial de plantas de arroz de terras altas inoculadas com a estirpe MAY12 de Azospirillum spp

ABSTRACT: The purpose of this study was to evaluate the contribution of the inoculation of the strain Azospirillum MAY12 to the development of rice plants of the cultivar BRS Esmeralda. A completely randomized experiment was performed in a greenhouse, with 8 treatments and 6 repetitions, namely, commercial inoculant (CI) containing strains of Azospirillum brasilense ABV5 and ABV6 (T1), MAY12 (T2), nitrogen control with 50 mg of N or full dose (T3), CI + 30% of N (percentage referring to full dose) (T4), CI + 60% N (T5), MAY12 + 30% N (T6), MAY12 + 60% N (T7) and absolute control (T8). There was a significant increase in the fresh and dry mass of the shoot and roots, height, root volume, and the number of tillers and leaves of plants with the MAY12 inoculation (with and without N added) compared to T8. Treatments containing MAY12 + N increased the total dry mass by ~920% compared to T8, matching the T3 yield. The inoculation of MAY12 in isolation was as efficient as the application of the full dose of N, resulting in an increase of ~115% in height and 373% in root volume of the plants compared to T8. The MAY12 strain demonstrated good performance in the development of the cultivar, which was comparable to the CI in the variables tested. Therefore, inoculation with the MAY12 strain is promising for the partial reduction of nitrogen fertilizers in upland rice cultivation.

RESUMO: O objetivo deste trabalho foi avaliar a contribuição da inoculação da estirpe de Azospirillum MAY12 no desenvolvimento de plantas de arroz da cultivar BRS Esmeralda. Foi realizado um experimento inteiramente casualizado em casa de vegetação, tendo oito tratamentos e seis repetições: inoculante comercial (IC) contendo as estirpes de Azospirillum brasilense AbV5 e AbV6 (T1), MAY12 (T2), testemunha nitrogenada com 50 mg de N ou dose cheia (T3), IC + 30% de N (percentual referente à dose cheia) (T4), IC + 60% de N (T5), MAY12 + 30% de N (T6), MAY12 + 60% de N (T7) e testemunha absoluta (T8). Houve aumento significativo da massa fresca e seca da parte aérea e de raízes, altura, volume de raízes e do número de perfilhos e de folhas das plantas com a inoculação de MAY12 (com e sem adição de N) em relação a T8. Os tratamentos contendo MAY12 + N aumentaram em torno de 920% a massa seca total em relação a T8, equiparando-se ao rendimento T3. A inoculação de MAY12, isoladamente, foi tão eficiente quanto a aplicação da dose cheia de N para o aumento em torno de 115% da altura e de 373% do volume de raízes das plantas em relação a T8. A estirpe MAY12 apresentou bom desempenho no desenvolvimento da cultivar equiparando-se com o IC nas variáveis testadas. Portanto, a inoculação com a estirpe MAY12 mostra-se promissora para a redução parcial de fertilizantes nitrogenados no cultivo de arroz de terras altas.

Changes induced by co-inoculation in nitrogen-carbon metabolism in cowpea under salinity stress

ABSTRACT To mitigate the deleterious effects of abiotic stress, the use of plant growth-promoting bacteria along with diazotrophic bacteria has been increasing. The objectives of this study were to investigate the key enzymes related to nitrogen and carbon metabolism in the biological nitrogen fixation process and to elucidate the activities of these enzymes by the synergistic interaction between Bradyrhizobium and plant growth-promoting bacteria in the absence and presence of salt stress. Cowpea plants were cultivated under axenic conditions, inoculated with Bradyrhizobium and co-inoculated with Bradyrhizobium sp. and Actinomadura sp., Bradyrhizobium sp. and Bacillus sp., Bradyrhizobium sp. and Paenibacillus graminis, and Bradyrhizobium sp. and Streptomycessp.; the plants were also maintained in the absence (control) and presence of salt stress (50 mmolL-1 NaCl). Salinity reduced the amino acids, free ammonia, ureides, proteins and total nitrogen content in nodules and increased the levels of sucrose and soluble sugars. The co-inoculations responded differently to the activity of glutamine synthetase enzymes under salt stress, as well as glutamate synthase, glutamate dehydrogenase aminating, and acid invertase in the control and salt stress. Considering the development conditions of this experiment, co-inoculation with Bradyrhizobium sp. and Bacillus sp. in cowpea provided better symbiotic performance, mitigating the deleterious effects of salt stress.

Mangrove endophyte promotes reforestation tree (Acacia polyphylla) growth

ABSTRACT Mangroves are ecosystems located in the transition zone between land and sea that serve as a potential source of biotechnological resources. Brazil's extensive coast contains one of the largest mangrove forests in the world (encompassing an area of 25,000 km2 along all the coast). Endophytic bacteria were isolated from the following three plant species: Rhizophora mangle, Laguncularia racemosa and Avicennia nitida. A large number of these isolates, 115 in total, were evaluated for their ability to fix nitrogen and solubilize phosphorous. Bacteria that tested positive for both of these tests were examined further to determine their level of indole acetic acid production. Two strains with high indole acetic acid production were selected for use as inoculants for reforestation trees, and then the growth of the plants was evaluated under field conditions. The bacterium Pseudomonas fluorescens (strain MCR1.10) had a low phosphorus solubilization index, while this index was higher in the other strain used, Enterobacter sp. (strain MCR1.48). We used the reforestation tree Acacia polyphylla. The results indicate that inoculation with the MCR1.48 endophyte increases Acacia polyphylla shoot dry mass, demonstrating that this strain effectively promotes the plant's growth and fitness, which can be used in the seedling production of this tree. Therefore, we successfully screened the biotechnological potential of endophyte isolates from mangrove, with a focus on plant growth promotion, and selected a strain able to provide limited nutrients and hormones for in plant growth.

The effect of FRAW towards the growth of chilli seedlings and its associated microorganisms

Abstract@#This study aims to evaluate the effect of Fermented Rice After-wash Water (FRAW) on chilli growth and to isolate microorganism present in three brands of white rice FRAW. The study showed that FRAW treatment was comparable with NPK fertiliser. In addition, a number of plant growth-promoting microbes associated with FRAW were also isolated. Isolated bacteria and fungi were then characterised according to their morphology and biochemical analysis. Thus the positive effect of FRAW on the chilli was likely due to the plant growth promoting microorganism present in FRAW.

Plant growth-promoting properties of free-living diazotrophic rhizobacteria from Tangerine (Citrus reticulate L.) var Batu 55

Aims@#Microbial cultures with multi-biological activities in increasing plant growth were developed to be an alternative way to reduce dependency on chemical fertilizer and to support plants productivity. The aims of this study were to characterize the potency of Tangerine var. Batu 55 diazotroph rhizobacteria as Plant Growth Promoting Rhizobacteria (PGPR) agents and to identify diazotroph rhizobacteria with multi-biological activities especially the activity of nitrogen fixation, ammonia (NH3) production, phosphate solubilizing, and Indole Acetic Acid (IAA) production.@*Methodology and results@#A total of 21 nitrogen-fixing bacteria (diazotroph) were isolated from Tangerine rhizosphere soil. Screening of PGPR isolates candidates were performed by in vitro assays consist of phytohormone Indole Acetic Acid (IAA) production, ammonia production, and phosphate-solubilizing assay. Candidates of PGPR isolates were identified based on 16S rDNA sequences. The result revealed that three isolates (Dbs 1, Dbs 2, and Dbm 3) had multibiological activities. Isolates of Dbs 1, Dbs 2, and Dbm 3 capable producing ammonia up to 10 μg/mL; 9.1 μg/mL; and 3.8 μg/mL, activity of IAA production were 30.08 μg/mL; 24.68 μg/mL; and 190.77 μg/mL, activity of phosphate solubilizing were 11.3 μg/mL; 8.6 μg/mL; and 2.2 μg/mL, respectively. Based on 16S rDNA, Dbs 1, Dbs 2, and Dbm 3 were identified as Acinetobacter schindleri, Pseudomonas syncyanea, and P. moraviensis, respectively. Based on our knowledge, this is the first report P. syncyanea was exhibited plant growth-promoting properties.@*Conclusion, significance and impact of study@#Candidates of PGPR isolates could be alternative PGPR agents, but still need to evaluate the effect of three PGPR isolates application on citrus plant growth.

Assessment of Rice Associated Bacterial Ability to Enhance Rice Seed Germination and Rice Growth Promotion

ABSTRACT The application of beneficial bacteria has recently been used for sustainable agriculture. In current research, 71 bacterial isolates were obtained from rice plant and the rhizosphere soil of different paddy fields in Guilan province, Iran. After primitive investigation, 40 bacteria with typical predominant characteristics were selected. By PCR-RFLP of their 16S r-DNA gene, 8 Operational Taxonomic Units (OTUs) totally consisted of 33 isolates were obtained. From all of them, 8 isolates were selected for rice seed germination experiment, then, effective isolates were used for pot experiment to evaluate their ability for promoting rice growth. All of them were able to increase rice growth and yield, but in different potential. These tested isolates were identified as Alcaligenes faecalis (DEp8, O1R4), Pantoea ananatis (AEn1), Bacillus vietnamensis (MR5), Bacillus idriensis (MR2) and Stenotrophomonas maltophilia by partial sequencing of their 16S r-DNA gene. Among them, AEn1 and MR5 produced indole-3- acetic acid (IAA) in larger amounts than the other isolates and the isolates AEn1 and O1R4 were able to solubilize phosphate in higher amounts. According to the results obtained, it can be concluded that AEn1, O1R4 and MR5 can be considered as bacterial inoculants to use as alternatives for chemical fertilizers.

Diazotrophic bacteria and nitrogen fertilization on the growth of micropropagated pineapple plantlets during acclimatization / Bactérias diazotróficas e adubação nitrogenada no crescimento de mudas micropropagadas de abacaxizeiro durante a aclimatização

ABSTRACT: This study examines the effect of inoculation with diazotrophic bacteria and nitrogen fertilization on the growth of micropropagated pineapple cv. 'Vitória' plantlets during the acclimatization period. The experiment was carried out in a greenhouse in Campos dos Goytacazes, in randomized blocks, using a 2x5x5 factorial scheme, with the factors being two types of inocula (absence or presence of a mixture of diazotrophic bacteria that contained Burkholderia sp. UENF 114111, Burkholderia silvatlantica UENF 11711, and Herbaspirillum seropedicae HRC 54), five levels of urea (0, 2, 5, 7, and 10g L-1), and five evaluation periods (30, 60, 90, 120, and 150 days following the planting of plantlets in trays), and with four replications of each treatment. An increase in the dried weight of shoots and roots of micropropagated pineapple cv. 'Vitória' plants depended on inoculation with diazotrophic bacteria, and plantlets acclimatization could be reduced by up to 57 days, depending on the concentration of urea fertilizer.

RESUMO: O objetivo deste trabalho foi estudar o efeito da inoculação de bactérias diazotróficas endofíticas e adubação nitrogenada no crescimento de mudas micropropagadas de abacaxizeiro 'Vitória' durante o período de aclimatização. O delineamento experimental foi de blocos casualizados (DBC), em esquema fatorial (2x5x5), sendo os fatores representados por dois tipos de inóculos (ausência e presença de uma mistura de bactérias diazotróficas contendo Burkholderia sp. UENF 114111, Burkholderia silvatlantica UENF 117111 e Herbaspirillum seropedicae estirpe HRC 54), cinco concentrações de ureia (0, 2, 5, 7 e 10g L-1) e em cinco épocas de avaliação do tempo de aclimatização (30, 60, 90, 120 e 150 dias após o plantio das mudas em bandejas), com quatro repetições. Verificou-se aumento na massa seca da parte aérea e massa seca da raiz de mudas micropropagadas de abacaxizeiro 'Vitória' em função da inoculação de bactérias diazotróficas. O tempo de aclimatização pode ser reduzida em até 60 dias em função da concentração de ureia.

La disminución de la población de Gluconacetobacter diazotrophicus en caña de azúcar, después de la fertilización nitrogenada, está relacionada con la fisiología de las plantas en experimentos de raíz dividida / The decrease in the population of Gluconacetobacter diazotrophicus in sugarcane after nitrogen fertilization is related to plant physiology in split root experiments

It has been established that a decrease in the population of Gluconacetobacter diazotrophicus associated with sugarcane occurs after nitrogen fertilization. This fact could be due to a direct influence of NH4NO3 on bacterial cells or to changes in plant physiology after fertilizer addition, affecting bacterial establishment. In this work, we observed that survival of G. diazotrophicus was directly influenced when 44.8 mM of NH4NO3 (640 mg N/plant) was used for in vitro experiments. Furthermore, micropropagated sugarcane plantlets were inoculated with G. diazotrophicus and used for split root experiments, in which both ends of the system were fertilized with a basal level of NH4NO3 (0.35 mM; 10 mg N/plant). Twenty days post inoculation (dpi) one half of the plants were fertilized with a high dose of NH4NO3 (6.3 mM; 180 mg N/plant) on one end of the system. This nitrogen level was lower than that directly affecting G. diazotrophicus cells; however, it caused a decrease in the bacterial population in comparison with control plants fertilized with basal nitrogen levels. The decrease in the population of G. diazotrophicus was higher in pots fertilized with a basal nitrogen level when compared with the corresponding end supplied with high levels of NH4NO3 (100 dpi; 80 days post fertilization) of the same plant system. These observations suggest that the high nitrogen level added to the plants induce systemic physiological changes that affect the establishment of G. diazotrophicus.

La población de Gluconacetobacter diazotrophicus asociada a la caña de azúcar disminuye después de la fertilización nitrogenada, lo cual podría ocurrir por la influencia directa del NH4NO3 sobre la supervivencia bacteriana, o por cambios en la fisiología de las plantas, que impiden el establecimiento bacteriano. En el presente trabajo se observó que en experimentos in vitro la supervivencia de G. diazotrophicus fue influenciada por 44,8 mM de NH4NO3 (640 mg N/plant). Además, G. diazotrophicus fue inoculado en plántulas micropropagadas de caña de azúcar, que fueron usadas para realizar experimentos de raíz dividida, en las que ambos extremos de los sistemas se fertilizaron con un nivel basal de NH4NO3 (0,35 mM; 10 mg N/planta). A los 20 días posteriores a la inoculación (dpi), la mitad de plantas fueron fertilizadas en uno de sus extremos con una dosis elevada de NH4NO3 (6,3 mM; 180 mg of N/plant). Este nivel fue menor al que afectó directamente a las células de G. diazotrophicus; sin embargo, provocó una disminución de la población bacteriana en comparación con plantas testigo fertilizadas con niveles basales de nitrógeno. La disminución de la población fue mayor para raíces fertilizadas con un nivel basal de nitrógeno en comparación con las raíces fertilizadas con altos niveles del mismo sistema de plantas (100 dpi; 80 días posfertilización). Estas observaciones indican que el alto nivel de nitrógeno añadido a las plantas inducen cambios fisiológicos sistémicos que afectan el establecimiento de G. diazotrophicus.

Análisis prospectivo de los bioinsumos agrícolas en Colombia: una consulta a expertos / Prospective analysis of agricultural bioinoculants in Colombia: an expert consultation

La productividad y sostenibilidad de la agricultura en Colombia pueden ser influidas positivamente a través del aprovechamiento de la biodiversidad para la producción de bioinsumos. Fueron analizados a mediano y largo plazo, los posibles escenarios futuros generados por las regulaciones que intervienen en el avance tecnológico de los bioinsumos, a través de la aplicación de una encuesta Delphi, con la participación de 23 expertos, teniendo en cuenta las tres dimensiones del desarrollo sostenible. Sobre la base de este estudio, se encontró que el 65% de los expertos consideran que el impacto de la innovación o el desarrollo tecnológico del uso de bioinsumos en la producción agrícola, tiene un alto impacto económico con un nivel de concordancia significativo (≥0.05). Adicionalmente, el 65% seleccionó como el mejor escenario, en el cual se den condiciones que promuevan mayor desarrollo, acceso y aplicación de los bioinsumos, de tal forma que se incremente el ritmo de incorporación de la tecnología por parte de los productores. En conclusión, más allá del nivel de desarrollo tecnológico, es necesario revisar los procesos legislativos para la comercialización de los bioinsumos, fue evidente que el éxito futuro de la industria de la producción de productos biológicos dependerá de la gestión de empresas innovadoras, la eficiente comercialización de los mismos, la educación y transferencia a los productores y el progreso de la investigación.

Productivity and sustainability of agriculture in Colombia can be influenced positively through the use of biodiversity for the production of bioinoculants. They were analyzed in the medium and long term, the future scenarios generated by the regulations involved in the technological advancement of bio-products through the application of a Delphi survey, with the participation of 23 experts in bio-products, taking into account the three dimensions sustainable development. Based on this study, it was found that 65% of the experts believe that the impact of innovation and technological development of the use of bio- products in agricultural production, has a high economic impact with a significant level of agreement (≥0.05). Additionally, 65% selected as the best scenario, in which conditions that promote greater development, access and application of bio-products, so that the rate of adoption of technology is increased by the producers to make. In conclusion, beyond the level of technological development is necessary to revise the legislative process for the marketing of bio-products, it was clear that the future success of the industry in the production of biological products depend on the management of innovative enterprises, efficient marketing thereof, education and transfer to producers and the progress of the investigation.

Perspectivas del uso de bacterias rizosféricas en el control de Pyricularia grisea (Cooke Sacc) en el cultivo del arroz (Oryza sativa L) / Prospect of the use of bacteria in the control Pyricularia grisea (Cooke Sacc) on rice (Oriza sativa L)

El arroz es fuente de alimento para una gran parte de la población mundial, con alto promedio de consumo anual. En este cultivo las enfermedades de origen microbiano constituyen uno de los factores que inciden en la obtención de bajos rendimientos y calidad de los granos. La piriculariosis o añublo del arroz, causada por Pyricularia grisea, es la enfermedad más importante en este cultivo en América Latina, ya que puede provocar hasta el 100% de reducción de los rendimientos. Como parte de la estrategia de agricultura sostenible, se trata de controlar estos patógenos y lograr altos rendimientos del cultivo mediante una combinación adecuada de fertilizantes químicos y productos biológicos. En este sentido, la aplicación de inoculantes bacterianos constituidos por bacterias promotoras del crecimiento vegetal (Plant Growth- Promoting Bacteria, PGPB, por sus siglas en inglés) ha constituido una alternativa ecológica que favorece la conservación del medioambiente y el ecosistema. Este trabajo tiene como objetivo abordar el estado actual y las perspectivas de uso de bacterias rizosféricas en el control de Pyricularia grisea en el cultivo del arroz, tratando algunos temas relevantes, como son las principales enfermedades que afectan al cultivo, los géneros de PGPB más utilizados para el control de las mismas y sus principales mecanismos de acción.

Rice is an important food supply for a large part of the world population and its consumption rates are very high. Microbial diseases are one of the main causes that provoke low yields and low-quality spotted grains. Although fungi, bacteria and viruses are mostly the responsible for these losses, fungal diseases strike more frequently. Among fungi, Pyricularia grisea, the blast fungus is responsible for up to 100% of reduction in yields, being the blast the most important rice disease in Latin America. To control this pathogen, a strategy of sustainable agriculture might be developed, combining accurately chemical and biological products. PGPB based bioproducts have been considered as an eco-friendly alternative, which favours environment preservation. This work was aimed to approach the current status and outlook of the use of rhizobacteria in the biocontrol of Pyricularia grisea on rice. Main diseases attacking rice, most beneficial PGPB and its mechanisms of action will be discussed too in this review.

Structural interaction between GFP-labeled diazotrophic endophytic bacterium Herbaspirillum seropedicae RAM10 and pineapple plantlets 'Vitória'

The events involved in the structural interaction between the diazotrophic endophytic bacterium Herbaspirillum seropedicae, strain RAM10, labeled with green fluorescent protein, and pineapple plantlets 'Vitória' were evaluated by means of bright-field and fluorescence microscopy, combined with scanning electron microscopy for 28 days after inoculation. After 6 hours of inoculation, H. seropedicae was already adhered to the roots, colonizing mainly root hair surface and bases, followed by epidermal cell wall junctions. Bacteria adherence in the initial periods occurred mainly in the form of solitary cells and small aggregates with pleomorphic cells. Bacteria infection of root tissue occurred through the cavities caused by the disruption of epidermal cells during the emergence of lateral roots and the endophytic establishment by the colonization of intercellular spaces of the cortical parenchyma. Moreover, within 1 day after inoculation the bacteria were colonizing the shoots. In this region, the preferred sites of epiphytic colonization were epidermal cell wall junctions, peltate scutiform trichomes and non-glandular trichomes. Subsequently, the bacteria occupied the outer periclinal walls of epidermal cells and stomata. The penetration into the shoot occurred passively through stoma aperture followed by the endophytic establishment on the substomatal chambers and spread to the intercellular spaces of spongy chlorenchyma. After 21 days of inoculation, bacterial biofilm were seen at the root hair base and on epidermal cell wall surface of root and leaf, also confirming the epiphytic nature of H. seropedicae.