ABSTRACT In the composition of the soil microbiome, there are numerous microorganisms capable of promoting plant growth, better known as plant growth-promoting microorganisms. The study aimed to determine the effects of multifunctional microorganisms, alone or in combination, on shoot, root, and total biomass production, gas exchange, macronutrient content, yield components, and grain yield of corn plants. The experiment was carried out in a greenhouse in a completely randomized design, with four replications. Twenty-six treatments consisted of isolated or combined microbiolization of corn seeds with the rhizobacteria Bacillus sp. (BRM 32109, BRM 32110, and BRM 63573), Burkholderia cepacea (BRM 32111), Pseudomonas sp. (BRM 32112), Serratia marcenses BRM 32113, Serratia sp. (BRM 32114), Azospirillum brasilense (Ab-V5), and Azospirillum sp. (BRM 63574), an isolated of fungus Trichoderma koningiopsis (BRM 53736), and a control treatment (without the application of microorganisms). At seven and 21 days, two more applications of the same treatments were carried out in the soil and the plants, respectively. The microorganisms applied alone or in combination promoted significant increases of 49% in corn plant biomass, 30% in gas exchange, 36% in macronutrient content, and 33% in grain yield. Isolates BRM 32114, Ab-V5, BRM 32110, and BRM 32112 and the combinations BRM 32114 + BRM 53736, BRM 63573 + Ab-V5, and BRM 32114 + BRM 32110 promoted better benefits to corn, allowing us to infer that the use of beneficial microorganisms significantly affects the development of corn plants.

RESUMO Na composição do microbioma do solo tem-se inúmeros microrganismos, capazes de promover o crescimento vegetal, mais conhecidos como microrganismos promotores de crescimento de plantas. Objetivamos determinar os efeitos de microrganismos multifuncionais, isoladamente ou em combinação, na produção de biomassa da parte aérea, raiz e total, nas trocas gasosas, no teor de macronutrientes, componentes de produção e produtividade de grãos de plantas de milho. O experimento foi conduzido em casa de vegetação em delineamento inteiramente casualizado, com quatro repetições. Utilizou-se 26 tratamentos que consistiram na microbiolização isolada ou combinada das sementes de milho com as rizobactérias BRM 32109, BRM 32110 e BRM 63573 (Bacillus sp.), BRM 32111 (Burkholderia cepacea), BRM 32112 (Pseudomonas sp.), BRM 32113 (Serratia marcenses) and BRM 32114 (Serratia sp.), Ab-V5 (Azospirillum brasilense) e BRM 63574 (Azospirillum sp.), um isolado de fungo BRM 53736 (Trichoderma koningiopsis) e um tratamento controle (sem a aplicação de microrganismos). Aos sete e 21 dias, foram realizadas mais duas aplicações dos mesmos tratamentos, no solo e nas plantas, respectivamente. Os microrganismos aplicados isoladamente ou em combinação promoveram incrementos significativos de 49% na biomassa das plantas de milho, 30% nas trocas gasosas, 36% no teor de macronutrientes e 33% na produtividade. Os isolados BRM 32114, Ab-V5, BRM 32110 e BRM 32112 e as combinações BRM 32114 + BRM 53736, BRM 63573 + Ab-V5 e 32114 + BRM 32110 promoveram melhores benefícios ao milho, nos permitindo inferir que o uso de microrganismos benéficos afetam significativamente o desenvolvimento das plantas de milho.

RESUMO As inoculações em plantas com mix de microrganismos benéficos podem melhorar significativamente o crescimento dessas e contribuir para uma agricultura sustentável. Entretanto, ainda existem questionamentos se inoculações em mix poderiam proporcionar resultados ainda melhores do que na forma isolada, sendo necessários estudos adicionais. Desta forma, objetivou-se avaliar os efeitos de microrganismos benéficos no desempenho da cultura do arroz de terras altas, em experimento conduzido em casa de vegetação, usando delineamento inteiramente casualizado, com três repetições e 26 tratamentos, que consistiram da inoculação de microrganismos isolados ou em mix de Bacillus sp., Serratia sp., Azospirillum sp., Bacillus spp., Azospirillum brasilense (Ab-V5) e um pool de Trichoderma asperellum, além do tratamento controle (sem aplicação de microrganismos). Os microrganismos afetaram significativamente as trocas gasosas, produção de biomassa e teor de nutrientes em plantas de arroz de terras altas. Os tratamentos mix BRM32114 + pool de T. asperellum, e Ab-V5 + pool de T. asperellum, foram mais efetivos, com destaque para as variáveis de trocas gasosas e teor de nutrientes. O tratamento mix 1301 + Ab-V5, apresentou maiores médias para produção de biomassa, com diferença significativa em relação ao tratamento controle.

ABSTRACT Inoculating plants with a mix of beneficial microorganisms can significantly improve plant growth and contribute to sustainable agriculture. However, it is unclear if mixed inoculations of microorganisms provide better results than inoculations of a single beneficial microorganism. Thus, the objective of this study was to evaluate the effects of beneficial microorganisms on the performance of upland rice in a greenhouse experiment using a completely randomized design with three repetitions and 26 treatments. The treatments consisted of inoculations of Bacillus sp. (BRM32110), Serratia sp. (BRM32114), Azospirillum sp. (1381), Bacillus sp. (1301), A. brasilense (Ab-V5) and a pool of Trichoderma asperellum in isolation or in a mixture in addition to a control treatment (without application of microorganisms). Microorganisms significantly affected gas exchange, biomass production and nutrient accumulation in upland rice plants. The mixed treatments of BRM32114 + pool of T. asperellum and Ab-V5 + pool of T. asperellum were more effective than the other treatments, with improved gas exchange variables and nutrient concentration. The 1301 + Ab-V5 mixed treatment showed higher averages for biomass production than the other treatments, and these values were significantly different from those of the control treatment.

This study aimed to assess the ability of silicon (Si) to potentiate defense enzyme activities in rice leaf sheaths and thus reduce sheath blight, caused by Rhizoctonia solani, development. Rice plants of BR-Irga 409 and Labelle cultivars were grown in a hydroponic solution containing 0 (-Si) or 2 mM (+Si) Si and inoculated with R. solani. Silicon concentration in the leaf sheaths was significantly higher in the +Si plants than the -Si plants by 727% for BR-Irga 409 and 714% for Labelle. The area under relative lesion expansion progress curve was significantly lower for +Si plants than -Si plants, by 34.2% for BR-Irga 409 and 30.59% for Labelle. Increases in the activities of phenylalanine ammonia-lyases, peroxidases, polyphenoloxidases and chitinases in the leaf sheaths of plants supplied with Si, especially of those from BR-Irga 409, led to reduced progress of sheath blight lesions.

Crude extract of an isolate of the fungus Sarocladium oryzae (CNPAF So 20G), containing the antimicrobial cerulenin, was produced and its antagonistic potential on the rice blast pathogen Magnaporthe oryzae was asessed. Cerulenin was detected in crude extract of S. oryzae through thin layer chromatography showing a Rf value of 0.63. The quantity of cerulenin in the crude extract was 237 µg.mL-1. The in vitro inhibition of germination and appressorial formation of M. oryzae was assessed on an artificial hydrophobic surface, using eight different doses of cerulenin ranging from 0.05 to 30.0 µg.mL-1. The LD50 values calculated based on the Probit-log analysis for germination and appressorial formation were 1.298 ± 0.123 µg.mL-1 and 0.0705 ± 0.0062 µg.mL-1 of cerulenin, respectively. The 30.0 µg.mL-1 of cerulenin dose inhibited 98% and 99%, germination and appressorial formation, respectively. The mode of action of cerulenin was studied by staining conidia with Calcofluor White and fluorescent microscopy showing its effect on plasma membrane. Crude extract of S. oryzae suppressed 63% of rice blast disease in greenhouse conditions. The results indicate that a product based on cerulenin and/or S. oryzae has a great potential to be used in biological control of rice blast.

A collection of Gaeumannomyces graminis var. graminis isolates obtained from symptomatic rice and grass plants in central and northern Brazil were studied in regard to pathogenicity on rice and cultural characteristics. For all isolates, only one type of lobed hyphopodia was observed both in the field and artificially inoculated plants. Perithecia were formed on artificial media and inoculated leaf sheaths. Hyphopodia were formed from ascosporic germ tubes. The hyphae under moist stress conditions produced dark brown chlamydospores that were initially hyaline. Large variation in the number of chlamydospores produced and duration of perithecia formation was observed among the isolates. Pathogenicity assays showed that 60-day old rice plants were more susceptible than 35-day old plants. The isolates from rice and grasses varied significantly in regard to disease severity on both rice seedlings and adult rice plants. In general, the isolates from rice were more aggressive than the isolates from grasses. Spontaneous infection of rice plants by ascosporic inoculum from perithecia on rice stubbles was observed in the greenhouse, suggesting their role as a source of primary inoculum in the field, which deserves further investigation.