RESUMO
The Tectona grandis L.f. (teak) is an important forest species with high economy value in Asia, Africa, and Latin America. In Latin America, Brazil is one of the countries with the most cultivated areas. The cultivation of teak turns out to be challenging because of its high nutritional demand and the need for seedling production by clonal propagation that includes about 90 days in the nursery phase. The optimization of seedling production is necessary for better results in the nursery and to enhance growth in the field. In this way, the well-known advantage of using microorganisms that promote plant development appears as a potential biotechnological approach to be explored and for the implantation of new areas of wood production. In this study, the inoculation of Bacillus subtilis as plant growth-promoting rhizobacteria (PGPR) was evaluated, and Rhizophagus clarus, an arbuscular mycorrhizal fungus (AMF), and the co-inoculation of these microorganisms in the teak seedling production phase can improve the development of commercial plantations under field conditions. Experiments were carried out under greenhouse and field conditions to evaluate four treatments based on the substrate inoculation of the seedlings. Treatments consisted of a non-inoculated control, PGPR inoculation, AMF inoculation, and PGPR + AMF inoculation. The results of the biometric evaluation of seedlings in the greenhouse showed that there was a significant difference in AMF inoculation and PGPR + AMF inoculation in terms of the specific root length and root density treatments, there was also a positive correlation between these two treatments and the absorption of some nutrients, such as P, N, K, Mg, Cu, Mn, and Zn. This response led to an increase between 4.75 and 11.04% in the field growth rate.
RESUMO
Beans are nutrient-demanding plants, with a high demand for nitrogen (N). Nitrogen biological fixation (NBF) is probably the best solution to meet this demand, especially considering losses in the soil-plantatmosphere system. Molybdenum (Mo), present in the enzymes nitrogenase and nitrate reductase, is fundamental in the metabolism of N, including NBF. This study aims to evaluate if bean seed inoculation with Azospirillum brasilense, Rhizobium tropici, and possible interactions with nitrogen topdressing and molybdenum leaf application, may affect winter bean development and yield. A randomized complete block design was used in a 4x2x2 factorial scheme. Plant population, production components, and grain yield were evaluated in two crop seasons (2017 and 2018). Seed inoculation with A. brasilense, when associated with 30 kg ha-1 N topdressing, increased plant population, pod number per plant and grain yield. Nitrogen topdressing is key to increasing winter bean productivity, regardless of inoculation or Mo foliar application.(AU)
O feijoeiro é uma planta exigente em nutrientes, com alta demanda por nitrogênio (N). A fixação biológica de N (FBN) é, provavelmente, a melhor solução para atender essa demanda, especialmente considerando as perdas no sistema solo-planta-atmosfera. O molibdênio (Mo), presente nas enzimas nitrogenase e redutase do nitrato, é fundamental no metabolismo do N, inclusive da FBN. Com objetivo de avaliar se a inoculação das sementes de feijão com Azospirillum brasilense, Rhizobium tropici, e possíveis interações com a adubação nitrogenada e molíbdica em cobertura tem efeito no desenvolvimento e na produtividade do feijoeiro, foi conduzida esta pesquisa. Utilizou-se delineamento experimental de blocos casualizados, em um esquema fatorial 4x2x2. Avaliou-se população de plantas, componentes de produção e produtividade de grãos, em dois cultivos (2017 e 2018). A inoculação das sementes, com A. brasilense, quando associada com 30 kg ha-1 de N em cobertura, incrementa a população de plantas, o número de vagens por planta e o rendimento de grãos. A adubação nitrogenada em cobertura é determinante no aumento de produtividade do feijão de inverno, independente da inoculação ou aplicação de Mo foliar.(AU)