Crescimento, acúmulo de nutrientes e fixação biológica de nitrogênio em Flemingia macrophylla [(Willd.) Merril]. / Growth, nutrient accumulation and biological nitrogen fixation in Flemingia macrophyla [(Willd.) Merril].

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Flemingia macrophylla is an underexploited Asian legume shrub in Brazil. International literature emphasizes its high potential as component in agroforestry systems in various regions of the tropics. The objective of this dissertation is to evaluate the potential of Flemingia macrophylla as an alternative green manure to be included in agroecological based systems. Two field experiments were conducted from December 12 2006 through December 19 2007. The first experiment was performed in Seropédica, at sea level, and the second, in Avelar, Paty do Alferes at 500 m altitude. On both experiments twelve monthly plant samplings were performed. Variables measured included stem diameter, number of follioles, and number of branches. Besides, in the first experiment, leaf area, root volumes and biomass, number of nodules and nutrients were quantified monthly. Estimates of biological nitrogen fixation were also accomplished by natural abundance of 15N. The experimental design was a randomized complete block with 12 treatments and four replicates. A previous germination test indicated that pre-incubation with 95% sulphuric acid for 20 minutes resulted in 88% germination, whereas immersion in 90oC water, 44%. On the filed experiments, plants performed better in Seropédica. The majority of variables were adjusted to second degree polynomial equations. Growth rates were adjusted to Gompertz model. Maximum heights were 1.8 and 1.4 m in Seropédica and Avelar, respectively. Biomass yields reached 4.1 Mg ha-1 in Seropédica and 2.3 Mg ha-1 in Avelar. Accumulation of N, P and K at 360 days after planting was 72.6 and 24.4 kg ha-1, respectively in Seropédica. The highest growth rate was found between 150 and 180 days. The percentage of N derived from biological N fixation was similar at 240, 300 and 360 day after planting, averaging 76.9%, which is equivalent to 62.2 kg N ha-1 at 360 days. The results indicate that Flemingia macrophylla may provide significant amounts of biomass and nutrients, especially N, being a promising species to be included in agroecological production systems.

ASSUNTO(S)

fitotecnia leguminosa shrub legume biomassa adubo verde green manure biomass

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