Adubação nitrogenada associada à inoculação com Azospirillum brasilense e Herbaspirillum seropedicae na cultura do milho

Abstract

Bactérias dos gêneros Azospirillum e Herbaspirillum são fixadoras de nitrogênio (N) atmosférico e consideradas promotoras do crescimento vegetal. Desta forma, desenvolveu-se o presente trabalho com o objetivo de avaliar o desenvolvimento e a produtividade do milho em resposta à inoculação de A. brasilense e H. seropedicae associada à adubação nitrogenada. O experimento foi conduzido em delineamento experimental de blocos ao acaso em esquema fatorial 4 x 5, com quatro repetições. Os tratamentos foram constituídos da inoculação de sementes (testemunha, estirpe de A. brasilense - Ab-V5, estirpe de H. seropedicae - SmR1 e combinação Ab-V5 + SmR1) e doses de N (0, 40, 80, 120 e 160 kg ha-1 de N). Foram avaliados: diâmetro basal do colmo, altura de planta, matéria seca de parte aérea e área foliar, nas fases vegetativa e reprodutiva, e produtividade. A adubação nitrogenada favoreceu o desenvolvimento da cultura até a máxima dose estudada. A inoculação combinada das estirpes proporcionou incrementos de 12% na matéria seca de parte aérea e 7% na produtividade em relação à testemunha indicando benefícios da combinação de bactérias diazotróficas que interagem de forma diferenciada com a planta.

Maize growth in response to Azospirillum brasilense, Rhizobium tropici, molybdenum and nitrogen

“…Pedrinho et al (2010), in a study on the activity of microorganisms in maize rhizosphere, observed phosphate solubilization and production of indole acetic acid (IAA) by bacteria of the genus Azospirillum. The increment of variables related to maize growth due to the isolated use of Azospirillum brasilense or combined use with N and/or other bacterial species has already been reported by Hungria et al (2010), Dartora et al (2013), Hahn et al (2013), Mazzuchelli et al (2014) and Marini et al (2015).…”

“…These results demonstrate that, when the seeds are co-inoculated and N fertilization is not applied, PH, BSD and SDM can be increased by 24, 11 and 35%, respectively (Table 3). Positive results of increment of height, stem diameter and shoot dry matter in maize were observed by Mazzuchelli et al (2014), for simultaneous use of Bacillus subtilis and Azospirillum brasilense, and by Dartora et al (2013), for the association of Azospirillum brasilense and Herbaspirillum seropedicae. In addition, Marks et al (2015) conducted a study about inoculation of Azospirillum brasilense and Rhizobium tropici metabolites in maize and observed increase in shoot dry matter, grain yield and N accumulation.…”

Inoculation of Diazotrophic Bacteria and Nitrogen Fertilization in Topdressing in Irrigated Corn

“…However, in corn production systems, the need for fertilizers is known as one of the factors that increases the production costs (COSTA et al, 2012b); in addition, its misuse can cause environmental harm. However, it is known that inoculating corn seeds with diazotrophic bacteria can improve the crop nitrogen supply (DARTORA et al, 2013;KAPPES et al, 2013) and can thereby reduce the need for externally applied nitrogen fertilizers.…”

“…One alternative to traditional fertilization methods is inoculation of corn seeds with diazotrophic bacteria, which has been found to decrease the need for nitrogen fertilizer application (LANA et al, 2012;KAPPES et al, 2013;DARTORA et al, 2013). Boddey and Döbereiner (1995) discovered the potential of microaerobic diazotrophic bacteria, especially those of the genus Azospirillum, to fix atmospheric nitrogen in free living condition.…”

“…The increase in corn yield due to inoculation with Azospirillum in trials conducted in Brazil is correlated with an increase in the absorption of not only nitrogen but also other nutrients such as phosphorus (P) and potassium (K) (DARTORA et al, 2013;KAPPES et al, 2013). These nutrients are of great importance in tropical soils, where they are naturally scarce.…”