Formas de inoculação de Rhizobium tropici e Azospirillum brasilense em feijoeiro-comum
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Data
2022-05-09
Autores
Gilabel, Amanda Prado [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Uma técnica que começa a ser explorada na cultura do feijão-comum é a coinoculação, que consiste na associação de bactérias do gênero Azospirillum com as do gênero Rhizobium. É possível que algumas bactérias, dentre elas as do gênero Azospirillum, beneficiem o crescimento da planta por uma combinação de vários mecanismos. No entanto, a inoculação/coinoculação pode ser realizada de formas distintas, gerando diferentes respostas no crescimento, desenvolvimento e produção das culturas. O objetivo desse trabalho foi avaliar as formas de inoculação da bactéria simbiótica (Rhizobium) e da bactéria associativa (Azospirillum), de maneira isolada ou coinoculada, no crescimento, nodulação, fixação biológica de N2, nutrição mineral e produtividade de grãos do feijoeiro-comum. Foram conduzidos dois experimentos, em condições de campo, na Fazenda Experimental Lageado, em Botucatu-SP, durante os períodos de março a julho (experimento 1) e agosto a dezembro (experimento 2) de 2019; e um experimento, também em condições de campo, na Fazenda Experimental da Unoeste, no município de Presidente Bernardes-SP, durante o período de abril a agosto de 2020 (experimento 3). Os experimentos foram conduzidos no delineamento de blocos ao acaso, com quatro repetições. Os tratamentos foram constituídos por três formas de inoculação com R. tropici (sem Rhizo, Rhizo semente e Rhizo sulco), combinadas ou não com quatro formas de inoculação com A. brasilense (sem Azo, Azo semente, Azo sulco e Azo foliar) mais um controle com N (120 kg ha-1 de N), em esquema fatorial 3x4+1, totalizando 13 tratamentos. Nos experimentos 2 e 3 foram inseridos mais dois tratamentos referentes ao fornecimento de N mineral (40 e 80 kg ha-1 de N). A cultivar de feijão-comum utilizada em todos os experimentos foi a BRS Estilo (Embrapa). Nos estádios fenológicos V4, R6 e R8 as plantas de feijão foram avaliadas quanto ao número (NN) e matéria seca de nódulos (MSN), crescimento radicular, matéria seca de raízes (MSR) e parte aérea (MSPA) e teor (NPA) e quantidade acumulada de N na parte aérea (NAPA) e abundância relativa de ureídos (ARU). Já no estádio R6 foram feitas avaliações relacionadas ao índice relativo de clorofila (Spad) e diagnose foliar. Por ocasião do encerramento do ciclo das plantas, foram avaliados os componentes da produção e produtividade de grãos (PG). Os resultados foram submetidos à análise de variância, pelo teste F. As médias dos tratamentos componentes do fatorial foram comparadas, pelo teste de Tukey a 5% de probabilidade. Por meio do teste de Dunnett (P≤0,05), os contrastes ortogonais dos tratamentos do fatorial foram comparados com a testemunha. Nos exps. 1 e 2, conduzidos em solo com textura argilosa, maior teor de matéria orgânica, fertilidade natural mais elevada e histórico de cultivo de feijão, a aplicação de R. tropici via sulco de semeadura e A. brasilense via sulco ou via foliar, proporcionaram os resultados mais promissores em termos de NN e MSN. Já para as condições do exp. 3 (solo arenoso, menor teor de matéria orgânica e fertilidade natural mais baixa), houve melhores respostas, em termos de nodulação, com a aplicação tanto de Rhizo, quanto de Azo, nas modalidades via sementes e sulco de semeadura, mas, não com as duas espécies juntas na mesma forma de inoculação. Foi observada redução tanto do NN, quanto da MSN, com o fornecimento de N mineral em todos os estádios fenológicos/experimentos. Houve resposta à adubação nitrogenada mineral para as variáveis relacionadas ao crescimento radicular (SR, CR e VR), MSR, MSPA, NPA e NAPA. Apesar disso, a aplicação de Rhizobium e Azospirillum também proporcionou efeito no crescimento radicular do feijão, com os resultados mais interessantes com as inoculações/coinoculações via sementes e sulco de semeadura, mas não com os microrganismos juntos na mesma via, principalmente nos exps. 1 e 2. A inoculação com Rhizobium via sementes incrementou a MSPA do feijoeiro, em V4 e R6, nas condições do exp. 3. Em relação aos teores foliares dos macro (N, P, K, Ca, Mg e S) e micronutrientes (Cu, Zn, Mn e Fe) do feijoeiro-comum, não houve efeito claro da inoculação/coinoculação de Rhizobium e Azospirillum. Quanto ao fornecimento de N mineral, houve algum efeito sobre os teores de N, K, Cu e Zn na folha diagnóstica do feijoeiro-comum. A inoculação, especialmente com Rhizobium, proporcionou incremento na ARU em comparação aos tratamentos sem inoculação. Contudo, a aplicação de Azospirillum via sulco e foliar, sem Rhizobium, também proporcionou resultados interessantes nessa variável. Houve redução ARU com a aplicação de N em todos os estádios fenológicos/experimentos. O fornecimento de N mineral incrementou o número de vagens por planta, especialmente, nos exps. 2 e 3. Quanto a PG, foi possível observar, em todos os experimentos, resultados muito próximos entre a inoculação/coinoculação de Rhizobium e Azospirilum e a aplicação de N mineral, seja de dose mais baixa (40 kg ha-1) ou mais elevada (120 kg ha-1). Apenas em solo mais arenoso (exp. 3), obtivemos respostas mais pronunciadas, em termos de PG, quando do fornecimento de N para a cultura do feijão-comum. Em relação as formas de inoculação, apesar dos resultados variados em alguns parâmetros, a aplicação de R. tropici e A. brasilense nas modalidades via sementes e sulco de semeadura, mas, não com as duas espécies juntas na mesma forma de inoculação, proporcionaram os resultados mais promissores.
A technique that is beginning to be explored in common bean is the co-inoculation, which consists of the association of bacteria of the genus Azospirillum with those of the genus Rhizobium. It is possible that some bacteria, including those of the genus Azospirillum, benefit plant growth by a combination of several mechanisms. However, inoculation/co-inoculation can be performed in different ways, generating different responses in the growth, development and production of crops. The aim of this study was to evaluate the ways of inoculation of the symbiotic bacterium (Rhizobium) and the associative bacterium (Azospirillum), alone or co-inoculated, in the growth, nodulation, biological N fixation, mineral nutrition and grain yield of common bean. Two experiments were carried out under field conditions at Lageado Experimental Farm, in Botucatu-SP, during the periods from March to July (trial 1) and from August to December (trial 2) of 2019; and an experiment, also under field conditions, at the Experimental Farm of Unoeste, in Presidente Bernardes-SP, during the period from April to August 2020 (trial 3). The experiments were carried out in a randomized block design, with four replications. The treatments consisted of three ways of inoculation with R. tropici, combined or not with four ways of inoculation with A. brasilense plus a control with N (120 kg ha-1 of N), in a 3x4+1 factorial scheme, totaling 13 treatments. In trials 2 and 3, two more treatments were added regarding the mineral N supply (40 and 80 kg ha-1 of N). In the phenological stages V4, R6 and R8, the common bean was evaluated for the nodules number (NN) and dry matter (MSN), root growth, roots dry matter (MSR) and shoot (MSPA) and content (NPA) and accumulated amount of N in the shoot (NAPA) and relative abundance of ureides (ARU). In the R6 stage, evaluations were made related to the relative chlorophyll index (Spad) and foliar diagnosis. At the end of the plant cycle, the components of production and grain yield (PG) were evaluated. The results were submitted to analysis of variance, using the F test. The means of the treatments components of the factorial were compared, using the Tukey test at 5% probability. Using Dunnett's test (P≤0.05), the orthogonal contrasts of the factorial treatments were compared with the control. In trials 1 and 2, carried out in soil with a clayey texture, higher organic matter content, higher natural fertility and history of bean cultivation, the application of R. tropici by sowing furrow and A. brasilense by furrow or foliar way, provided the most promising results in terms of NN and MSN. For the conditions of exp. 3 (sandy soil, lower organic matter content and lower natural fertility), there were better responses, in terms of nodulation, with the application of both Rhizo and Azo, by seeds and sowing furrow, but not with the two species together in the same inoculation method. A reduction in both NN and MSN was observed with the supply of mineral N in all phenological stages/experiments. There was a response to mineral N fertilization for variables related to root growth (SR, CR and VR), MSR, MSPA, NPA and NAPA. Despite this, the application of Rhizobium and Azospirillum also had an effect on common bean root growth, with the most interesting results with inoculation/co-inoculation by seeds and sowing furrow, but not with microorganisms together in the same way, especially in exp. 1 and 2. Inoculation with Rhizobium by seeds increased the bean MSPA, in V4 and R6, under the 12 conditions of exp. 3. Regarding the foliar contents of macro (N, P, K, Ca, Mg and S) and micronutrients (Cu, Zn, Mn and Fe) of bean, there was no clear effect of inoculation/co-inoculation of Rhizobium and Azospirillum. As for the supply of mineral N, there was some effect on the levels of N, K, Cu and Zn in the common bean diagnostic leaf. Inoculation, especially with Rhizobium, provided an increase in ARU compared to treatments without inoculation. However, the application of Azospirillum by furrow and foliar, without Rhizobium, also provided interesting results in this variable. There was a reduction in ARU with the application of N in all phenological stages/experiments. The supply of mineral N increased the number of pods per plant, especially in exp. 2 and 3. For PG, it was possible to observe, in all trials, very similar results between the inoculation/co-inoculation of Rhizobium and Azospirilum and the application of mineral N, whether at a lower rate (40 kg ha-1 ) or higher rate (120 kg ha1 ). Only in more sandy soil (exp. 3), we obtained more pronounced responses, in terms of PG, when supplying N to the common bean crop. Regarding the inoculation methods, despite the varied results in some parameters, the application of R. tropici and A. brasilense by seeds and sowing furrow, but not with the two species together in the same way, provided the best results
A technique that is beginning to be explored in common bean is the co-inoculation, which consists of the association of bacteria of the genus Azospirillum with those of the genus Rhizobium. It is possible that some bacteria, including those of the genus Azospirillum, benefit plant growth by a combination of several mechanisms. However, inoculation/co-inoculation can be performed in different ways, generating different responses in the growth, development and production of crops. The aim of this study was to evaluate the ways of inoculation of the symbiotic bacterium (Rhizobium) and the associative bacterium (Azospirillum), alone or co-inoculated, in the growth, nodulation, biological N fixation, mineral nutrition and grain yield of common bean. Two experiments were carried out under field conditions at Lageado Experimental Farm, in Botucatu-SP, during the periods from March to July (trial 1) and from August to December (trial 2) of 2019; and an experiment, also under field conditions, at the Experimental Farm of Unoeste, in Presidente Bernardes-SP, during the period from April to August 2020 (trial 3). The experiments were carried out in a randomized block design, with four replications. The treatments consisted of three ways of inoculation with R. tropici, combined or not with four ways of inoculation with A. brasilense plus a control with N (120 kg ha-1 of N), in a 3x4+1 factorial scheme, totaling 13 treatments. In trials 2 and 3, two more treatments were added regarding the mineral N supply (40 and 80 kg ha-1 of N). In the phenological stages V4, R6 and R8, the common bean was evaluated for the nodules number (NN) and dry matter (MSN), root growth, roots dry matter (MSR) and shoot (MSPA) and content (NPA) and accumulated amount of N in the shoot (NAPA) and relative abundance of ureides (ARU). In the R6 stage, evaluations were made related to the relative chlorophyll index (Spad) and foliar diagnosis. At the end of the plant cycle, the components of production and grain yield (PG) were evaluated. The results were submitted to analysis of variance, using the F test. The means of the treatments components of the factorial were compared, using the Tukey test at 5% probability. Using Dunnett's test (P≤0.05), the orthogonal contrasts of the factorial treatments were compared with the control. In trials 1 and 2, carried out in soil with a clayey texture, higher organic matter content, higher natural fertility and history of bean cultivation, the application of R. tropici by sowing furrow and A. brasilense by furrow or foliar way, provided the most promising results in terms of NN and MSN. For the conditions of exp. 3 (sandy soil, lower organic matter content and lower natural fertility), there were better responses, in terms of nodulation, with the application of both Rhizo and Azo, by seeds and sowing furrow, but not with the two species together in the same inoculation method. A reduction in both NN and MSN was observed with the supply of mineral N in all phenological stages/experiments. There was a response to mineral N fertilization for variables related to root growth (SR, CR and VR), MSR, MSPA, NPA and NAPA. Despite this, the application of Rhizobium and Azospirillum also had an effect on common bean root growth, with the most interesting results with inoculation/co-inoculation by seeds and sowing furrow, but not with microorganisms together in the same way, especially in exp. 1 and 2. Inoculation with Rhizobium by seeds increased the bean MSPA, in V4 and R6, under the 12 conditions of exp. 3. Regarding the foliar contents of macro (N, P, K, Ca, Mg and S) and micronutrients (Cu, Zn, Mn and Fe) of bean, there was no clear effect of inoculation/co-inoculation of Rhizobium and Azospirillum. As for the supply of mineral N, there was some effect on the levels of N, K, Cu and Zn in the common bean diagnostic leaf. Inoculation, especially with Rhizobium, provided an increase in ARU compared to treatments without inoculation. However, the application of Azospirillum by furrow and foliar, without Rhizobium, also provided interesting results in this variable. There was a reduction in ARU with the application of N in all phenological stages/experiments. The supply of mineral N increased the number of pods per plant, especially in exp. 2 and 3. For PG, it was possible to observe, in all trials, very similar results between the inoculation/co-inoculation of Rhizobium and Azospirilum and the application of mineral N, whether at a lower rate (40 kg ha-1 ) or higher rate (120 kg ha1 ). Only in more sandy soil (exp. 3), we obtained more pronounced responses, in terms of PG, when supplying N to the common bean crop. Regarding the inoculation methods, despite the varied results in some parameters, the application of R. tropici and A. brasilense by seeds and sowing furrow, but not with the two species together in the same way, provided the best results
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Palavras-chave
Azospirillum brasilense, Fixação biológica de nitrogênio, Nutrição mineral de plantas, Phaseolus vulgaris, Rhizobium tropici, Biological nitrogen fixation, Mineral plant nutrition