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Core Ideas A full set of N2–fixing nodules can supply soybean N demands.Seed inoculation increased nodulation and grain yield of field‐grown soybean.Additional spray inoculations (V1, V3, V6, R1, or R3) resulted in further increases.New nodules and grain yield increases can be achieved by additional inoculations. Highly productive soybean [Glycine max (L.) Merr.] genotypes require that large amounts of N be supplied throughout the growth cycle to attain high yields. The nutrient can be obtained through biological N2 fixation by elite bradyrhizobial strains if a set of fully functional nodules is available. This study was conducted during two crop seasons in the central‐west region of Brazil to investigate if additional inoculations via spray applications of bradyrhizobia at different stages of the growth cycle can result in increased nodulation and grain yield. Even though the soils had high populations of soybean bradyrhizobia, seed inoculation at sowing increased grain yield by 28 and 27% in the first and second seasons, respectively, compared to the non‐inoculated control. Additional inoculations performed until the R6 stage significantly increased soybean nodulation, which might indicate that plants were able to overcome the limitations of autoregulation of nodulation, allowing the development of new functional nodules to sustain the increased demand for N at latter stages of the growth cycle, especially during pod filling. In response to the increased nodulation, grain yield gains of 2 and 7% were obtained in the first and second experiments, respectively, relative to inoculation at sowing only. Our results indicate that soybean roots can form new nodules in response to additional inoculations, promoting increased N2 fixation and higher grain yield.

Rhizobia and other plant growth‐promoting rhizobacteria (PGPR) have been broadly used as inoculants in agriculture, resulting in morphofunctional improvements in roots and grain yield. This study was carried out during two cropping seasons under field and greenhouse conditions in Brazil to verify the effects of inoculation of two soybean cultivars with PGPR and secondary microbial metabolites (SMMs) on root activity and nodulation, plant development, and grain yield. Inoculation and co‐inoculation treatments consisted of Bradyrhizobium japonicum strain SEMIA 5079 and B. diazoefficiens strain SEMIA 5080 inoculated together, in combination with Bacillus subtilis strain QST 713, Azospirillum brasilense strains Ab‐V5 and Ab‐V6, and SMMs extracted from B. diazoefficiens strain USDA 110 and Rhizobium tropici strain CIAT 889. Root systems were evaluated by direct (optical reading) and indirect (rubidium nitrate application, 85RbNO3) methods. Increases of up to 1.6% in root diameter (0.01‐ to 0.5‐mm class), 28.5% in length, 19.7% in root volume, 17.8% in root surface area, 29% in the number of nodules, 27.2% in nodule dry weight, 13.5% in root dry weight, and 3.8% in shoot dry weight. Greater exploration and activity within and between rows following inoculation at up to 40 and 10 cm in depth, respectively, were observed in plants co‐inoculated with the standard inoculation (only Bradyrhizobium spp.) + SMMs + A. brasilense, resulting in a yield increase of 485 kg ha−1. The results emphasize the biotechnological potential of using secondary metabolites of rhizobia with inoculants containing rhizobia and PGPR to improve the growth and soybean yield in tropical conditions.

AGRADECIMENTOSPrimeiramente a Deus, por ter me concedido a vida e por permitir que eu vencesse mais este desafio, com sua bênção e proteção.A minha querida esposa Sheila Caioni, pelo amor, carinho, companheirismo e compreensão. E por ter estado sempre ao meu lado, auxiliando de forma direta em todas as etapas de desenvolvimento deste projeto e durante todo o mestrado.Aos meus pais Antônio de Lisboa Parente e Maria Aparecida Parente, e todos os familiares e amigos, que sempre incentivaram, dando apoio e torcendo por mais essa conquista.A Universidade Estadual Paulista "Júlio de Mesquita Filho", Campus de Ilha Solteira, por me conceder o título de Mestre em Agronomia, e pela infraestrutura e material cedido.A CAPES, pela concessão da bolsa de estudos, permitindo assim a dedicação à pesquisa por tempo integral.Ao professor Dr. Edson Lazarini, ao qual tive a honra de ter como orientador e amigo, que com sua experiência e conhecimentos sempre me orientou e participou de forma direta na execução do projeto.Aos colegas da "Equipe Edson Lazarini", pela amizade e pelo auxílio direto na fase de campo do projeto.Aos colaboradores da Fazenda de Ensino Pesquisa e Extensão (FEPE) de Selvíria, que também auxiliaram na condução do experimento.A todos os demais professores, colegas e servidores da UNESP, que de alguma forma colaboraram durante o período de Mestrado, muito obrigado."Quando Deus fez a terra e o céu, ainda não havia na terra nenhuma planta do campo, pois no campo ainda não havia brotado nenhuma erva: Deus não tinha feito chover sobre a terra e não havia homem que cultivasse o solo e fizesse subir da terra a água para regar a superfície do solo. Então Deus modelou o homem com a argila do solo, soprou-lhe nas narinas um sopro de vida, e o homem tornou-se um ser vivente." "Deus fez brotar do solo todas as espécies de árvores formosas de ver e boas de comer." "Deus tomou o homem e o colocou no jardim de Éden, para que o cultivasse e guardasse." GÊNESIS 2,4b-7.9.15 RESUMO A inoculação de sementes na cultura da soja, com bactérias do gênero Bradyrhizobium, que fixam o nitrogênio atmosférico, é amplamente utilizada pelos produtores agrícolas por conta de fornecer o aporte necessário deste nutriente à planta, dispensando assim a adubação mineral nitrogenada. No entanto, ainda há questionamentos sobre sua eficiência em suprir a demanda do nutriente para as cultivares atuais, cada vez mais produtivos, e consequentemente, mais exigentes nutricionalmente. Isso leva alguns pesquisadores e até mesmo produtores a levantarem a hipótese de que, mesmo com a fixação biológica de nitrogênio, a aplicação de doses complementares deste nutriente em algum estádio de desenvolvimento da planta seja capaz de promover ganhos significativos no rendimento de grãos. Desta forma, o objetivo deste trabalho foi avaliar o efeito da adubação mineral nitrogenada associada à inoculação na soja. O experimento foi conduzido na Fazenda Experimental da Faculdade de Engenharia, Campus de Ilha Solteira, Selvíria-MS. O delineamento foi o de blocos ao acaso no...

Drought stress is an important concern worldwide which reduces crop yield and quality. To alleviate this problem, Trichoderma asperellum has been used as a plant growth-promoting fungus capable of inducing plant tolerance to biotic and abiotic stresses. Here, we examined the effect of T. asperellum inoculation on sugarcane plant above and belowground development under drought stress and investigated the role of this fungus on inducing tolerance to drought at physiological and biochemical levels. The experiment was performed in pots under greenhouse conditions, with four treatments and four replicates. The treatments consisted of sugarcane plants inoculated or not with T. asperellum and grown under drought stress and adequate water availability. Drought-stressed sugarcane plants inoculated with T. asperellum changed the crop nutrition and chlorophyll and carotenoid concentrations, resulting in increased photosynthesis rate, stomatal conductance, and water use efficiency compared to the non-inoculated plants. In addition, the antioxidant metabolism also changed, increasing the superoxide dismutase and peroxidase enzyme activities, as well as the proline concentration and sugar portioning. These cascade effects enhanced the root and stalk development, demonstrating that T. asperellum inoculation is an important tool in alleviating the negative effects of drought stress in sugarcane. Future studies should be performed to elucidate if T. asperellum should be reapplied to the sugarcane ratoons.

The effects of Bradyrhizobium inoculation on soybean growth and productivity are well known, but plant responses to consortia of other beneficial microbes and microbial molecules have not yet been well explored. Therefore, the main aim of this study was to evaluate the effect of different combinations of beneficial bacteria with and without microbial secondary metabolites (MSM) on two soybean cultivars in three cropping seasons under tropical field conditions. The bacterial consortia consisted of Bradyrhizobium japonicum (strain SEMIA 5079) plus Bradyrhizobium diazoefficiens (strain SEMIA 5080) inoculated with different combinations of Bacillus subtilis (strain QST 713), Azospirillum brasilense (strains Ab-V5 and Ab-V6), and MSM (metabolites enriched in lipo-chitooligosaccharides (LCOs) extracted from B. diazoefficiens (strain USDA 110) and from Rhizobium tropici (strain CIAT 889)). Standard inoculation of Bradyrhizobium combined with Azospirillum brasilense and microbial secondary metabolites increased leaf total N (7.1%), total P (11.1%), and N-ureide (16.5%); nodule number (NN, 26%) and dry weight (NDW, 22%); root (RDW, 15.4%) and shoot dry weight (SDW, 6%); 100-seed weight (3.7%); grain yield (up to 516 kg ha −1 ); grain crude protein concentration (2.4%); and the agronomic efficiency index (AEI) (11%). Inoculation with bacterial consortia and metabolites increased grain yield and quality, representing a promising technology for sustainable soybean cropping in tropical regions.

T here was a mistake in the dilution calculation in the estimate of protein content of Table 6. Therefore, the values should be divided by 1.5. Statistics has not changed, and differences were not statistically significant.

Foliar fertilization has been used as a supplemental strategy to plant nutrition especially in crops with high yield potential. Applying nutrients in small doses stimulates photosynthesis and increases yield performance. The aim of this study was to evaluate the efficiency of foliar application of molybdenum (Mo) to soybean and maize. The treatments consisted of the presence (+Mo) and absence (-Mo) of supplementation. Plant nutritional status, nitrate reductase (NR) activity, gas exchange parameters, photosynthetic enzyme activity (Rubisco in soybean and maize and PEPcase in maize), total soluble sugar concentration, leaf protein content, shoot dry matter, shoot nitrogen accumulated, number of grains per plant, mass of 100 grains, and grain yield were evaluated. For soybean and maize, application of Mo increased leaf NR activity, nitrogen and protein content, Rubisco activity, net photosynthesis, and grain yield. These results indicate that foliar fertilization with Mo can efficiently enhance nitrogen metabolism and the plant’s response to carbon fixation, resulting in improved crop yields.