Resumen de Morphogenesis of canarana grass with two frequencies and two defoliation intensities

D. Rodrigues Chaves, M.J. Duarte Cândido, Rafael Nogueira Furtado, R.C. Fernandes Franco Pompeu, T. Duarte Maranhão

• español

  Objetivou-se avaliar o fluxo de biomassa do capim-canarana erecta lisa (Echinochloa pyramidalis LAM.) pastejado por novilhas leiteiras num delineamento em blocos casualizados com cinco repetições (piquetes) e arranjo fatorial 2 x 2 (frequência e intensidade). As frequências de desfolhação (FD) corresponderam à intercepção de 85 e 95% da radiação fotossinteticamente ativa e as intensidades de desfolhação (ID) corresponderam aos índices de área foliar residual 1,0 e 2,0. Foram avaliadas as seguintes variáveis: a taxas de alongamento foliar (TAlF) e das hastes (TAlH), a razão entre a taxa de alongamento da folha 1 e da folha 2 (TAlF1/TAlF2), taxa de senescência total (TST), o número de folhas vivas (NFV), o número de folhas totais (NFT); o tempo de vida da folha (TVF); a taxa de aparecimento da folha (TApF) e a taxa de acúmulo da cultura (TAC). A TAlF1/TAlF2, TAlF, TAlH e TST não foram influenciada pelas FD e ID, mas aumentaram com os ciclos. A TApF foi maior na FD de 85% em relação a FD de 95%. O capim-canarana pastejado por novilhas deve ser manejado com frequência de desfolhação de 95% de interceptação da radiação fotossinteticamente ativa associada a um índice de área foliar residual de 2,0.

• English

  To evaluate the biomass flow of canarana grass erecta lisa (Echinochloa pyramidalis LAM.) grazed by dairy heifers, this study was conduct. It was a complete randomized block design with five replicates (paddocks) and a factorial arrangement 2 x 2 (frequency and intensity). The defoliation frequencies (DF) corresponded to interception from 85 and 95% of photosynthetic active radiation, and the defoliation intensity (DI) corresponded to the residual leaf area index 1,0 and 2,0. Were evaluated: leaf elongation rate (LER), and stem (SER), the elongation rate of the leaf 1/elongation rate of the leaf 2 (ERL1/ERL2), leaf total senescence rate (LTSR), leafs live number (LLN) and total leafs number (TLN), life leaf time (LLT), leaf appearance rate (LAR) and crop accumulation rate (CAR). The ERL1/ERL2, LER, SER and LTSR were not influenced by DF and DI but increased with cycles. LAR was higher in DF than 85% in relation to DF of 95%. Canarana grass grazed by heifers should be managed with a frequency of 95% defoliation of the photosynthetically active radiation associated with a residual leaf area index of 2,0.