Efeitos da inoculação de mudas de farinha-seca (Albizia niopoides (Spruce ex Benth.) Burkart) com bactéria diazotrófica e adubação nitrogenada em viveiro
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2017-08-17
Autores
Silva, Rafael Barroca
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Universidade Estadual Paulista (Unesp)
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A inoculação de leguminosas arbóreas nativas com bactérias fixadoras de nitrogênio (BFN) pode favorecer a produção de mudas e até mesmo o sucesso no plantio definitivo, em campo. A adubação nitrogenada é fator importante no desempenho da fixação biológica em leguminosas, podendo reduzi-la ou inibi-la. Este trabalho testou os efeitos da inoculação de mudas de farinha-seca (Albizia niopoides (Spruce ex Benth.) Burkart) com Bradyrhizobium elkanii, estirpe BR 5611, e de cinco níveis de nitrogênio aplicados via ureia em solução nutritiva, semanalmente. As plantas foram mantidas em tubetes de 115 cm3 com substrato comercial à base de turfa. Acompanhou-se o crescimento ao longo do tempo, e no final também foram feitas avaliações de nodulação, teor e conteúdo de N e teor indireto de clorofila. Neste experimento, a produção das mudas se estendeu por quase um ano. Tanto a inoculação com rizóbios quanto as doses de nitrogênio aplicadas influenciaram o crescimento das mudas. A inoculação com BFN reduziu a necessidade de fertilização nitrogenada para as mudas atingirem valores máximos de altura e biomassa. Foi estimada a dose de 663 mg L-1 de N para a altura máxima nas plantas inoculadas, contra 1136 mg L-1 de N no grupo sem inoculação. Doses maiores, de 1000 e 2000 mg L-1 de N ocasionaram redução acentuada de nodulação, além de prejudicar o crescimento das mudas, especialmente a formação de raízes.
The inoculation of native legume trees with rhizobia (that perform biological nitrogen fixing – BNF) may support production of seedlings and even success at post-planting in the field. Nitrogen fertilization is an important factor in BNF performance in legumes, which may be reduced or inhibited depending on nitrogen levels. This study evaluated the effects of inoculation of Albizia niopoides (Spruce ex Benth.) Burkart seedlings with Bradyrhizobium elkanii (strain BR 5611) and five rates of nitrogen applied via urea on plant growth. The seedlings were grown in plastic bags (115 cm3) filled with peat-based commercial substrate. Growth was measured during the period of seedlings production, and seedling quality indices, nodulation, N content on tissues and indirect content of chlorophyll in leaves were also evaluated at end. Production of seedlings has lasted for almost a year. Both N-fertilization and inoculation with rhizobia influenced plant growth. The requirement of nitrogen fertilization to attain the maximum height and biomass was smaller when seedlings were inoculated with rhizobia. It was estimated a dose of 663 mg L-1 of N for maximum height in inoculated seedlings, whereas 1136 mg L-1 in non-inoculated plants. Higher doses of 1000 and 2000 mg L-1 of N, induced marked reduction of nodulation, besides harmed growth of seedlings, notably the roots generation.
The inoculation of native legume trees with rhizobia (that perform biological nitrogen fixing – BNF) may support production of seedlings and even success at post-planting in the field. Nitrogen fertilization is an important factor in BNF performance in legumes, which may be reduced or inhibited depending on nitrogen levels. This study evaluated the effects of inoculation of Albizia niopoides (Spruce ex Benth.) Burkart seedlings with Bradyrhizobium elkanii (strain BR 5611) and five rates of nitrogen applied via urea on plant growth. The seedlings were grown in plastic bags (115 cm3) filled with peat-based commercial substrate. Growth was measured during the period of seedlings production, and seedling quality indices, nodulation, N content on tissues and indirect content of chlorophyll in leaves were also evaluated at end. Production of seedlings has lasted for almost a year. Both N-fertilization and inoculation with rhizobia influenced plant growth. The requirement of nitrogen fertilization to attain the maximum height and biomass was smaller when seedlings were inoculated with rhizobia. It was estimated a dose of 663 mg L-1 of N for maximum height in inoculated seedlings, whereas 1136 mg L-1 in non-inoculated plants. Higher doses of 1000 and 2000 mg L-1 of N, induced marked reduction of nodulation, besides harmed growth of seedlings, notably the roots generation.
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rizóbios, Bradyrhizobium elkanii, biotecnologia, viveiro florestal, essências nativas, biotechnology, nursery, native species