Morfogênese, acúmulo de forragem e teores de nutrientes de Panicum maximum cv. Tanzânia submetido a diferentes severidades de desfolhação e fertilidades contrastantes / Morphogenesis, forage net accumulation and nutritional status of Panicum maximum cv Tanzânia under contrasting fertilization rates and grazing intensities

AUTOR(ES)

Alonso José de Resende Junior

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

05/12/2011

RESUMO

Nitrogen is the most important nutrient regulating pasture production. Response to N fertilization depends on residual leaf area index and other nutrient availability. The aim of this study was to evaluate morphogenetic and structural characteristics, grazing interval, forage yield and nutritional status of Tanzania guinea grass under contrasting defoliation severities and fertilization rates. The six treatments evaluated were factorial combinations between three post grazing heights (20, 30 e 50 cm) and two fertilization rates (unfertilized and fertilized with 500, 300 and 150 kg/ha of nitrogen, K2O e P2O5 respectively), arranged in five completed blocks, totaling 30 paddocks (experimental units) of 400 m² each.25 beef cattle animals were introduced into paddocks to graze every time sward reached 95% of light interception.Measured responses were leaf appearance rate, phyllochron, leaf elongation rate, stem elongation rate, leaf senescence rate, leaf life span, leaf mature length, live leafs per tiller, elongating leafs per tiller, mature leafs per tiller,senescent leafs per tiller and stem length.Nutritional status was measured in the two younger mature leavesof each tiller, considering 100 leaves sampled from 50 tillers of each paddockbetween May and April 2010. Fertilized and unfertilized treatments presented contrasting nutritional status. A high fertilization level combined with the lowest post grazing height resulted in the higher forage yields and leaf elongation rates. The results point to the possibility of enhancing grazing efficiency and animal production when high fertilizations are combined with high grazing intensity

ASSUNTO(S)

capim-tanzânia defoliation desfolha morfogênese vegetal morphogenesis nitrogen nitrogênio pasture - management tanzania guinea grass pastagens - manejoi

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