Características morfogênicas e estruturais do capim-Xaraés submetido a intensidades de desfolhas

Abstract

Objetivou-se avaliar as características morfogênicas e estruturais do capim-Xaraés submetido a cinco alturas de cortes (10; 20; 30; 40 e 50cm) com intervalo de corte baseado na interceptação luminosa (IL) pelo dossel durante a rebrotação (95% de IL). Utilizou-se o delineamento inteiramente casualizado, num fatorial 5 x 2, com cinco repetições. As avaliações foram realizadas de março a novembro de 2011, nas variáveis: taxa de aparecimento foliar (TApF), taxa de alongamento foliar (TALF), taxa de alongamento do colmo (TALC), comprimento final da folha (CF), taxa de senescência foliar (TSF), duração de vida das folhas (DVF), número de folhas vivas por perfilho (NFV) e número vivo de perfilhos (NVP). Observou-se que as alturas de cortes de 30 a 50 cm, resultaram em maior TALC, TALF, TApF, TSF, DVF, NFV e CF. As características TALC, TALF, TApF, TSF, NFV e CF apresentou valores mais elevados durante o período chuvoso. Enquanto, o filocrono e, a DVF em 40 cm apresentou valores mais elevados no período da seca. O NVP não foi afetado pelas alturas de cortes ou época do ano. A altura de corte do capim-Xaraés recomendada para essas condições edafoclimáticas situa-se entre 30 e 50cm.

Structural characteristics and chemical composition of andropogon grass pasture managed under different defoliation intensities and rest periods

“…In the lower rest period, there was higher production of leaves and lower production of stems, as the rest period was prolonged, the reverse occurred. In addition, the tiller population density may have contributed, since in the lower rest period there was a higher density in relation to the period of 55 days (Table 2), thus characterizing the size/density compensation mechanism, that is, high density of light tillers and low density of heavy tillers, as reported by Sbrissia & Silva (2008). The rest period promoted a linear decreasing effect (P <0.05) on the leaf/stem ratio in the two defoliation intensities.…”

“…There was effect of defoliation intensity on DPP (P <0.05); and the lowest density was observed at the height of 30 cm, resulting from the greater shading in the base of the tiller (Table 2) Sward height increased linearly (P <0.05) according to defoliation intensities ( Table 2). The increase in height with the increase of the rest period is related to the greater stem elongation, which is due to the lower DPP observed, because, according to Sbrissia & Silva (2008), pastures under long rest periods have low DPP, however longer tillers, culminating, thus, in greater sward height. No effect (P> 0.05) from the interaction between rest periods and defoliation intensity was verified on dry matter, crude protein, neutral detergent fiber (NDF), acid detergent fiber (ADF) and lignin (Table 3).…”

“…The reduction in the DPP can be explained by the size/density compensation mechanism of tillers, since the rest period of 25 days presented high density, with the extension of the period, there is selfthinning of the smaller tillers to the detriment of the growth of the larger tillers (SBRISSIA & SILVA, 2008), thus ensuring heavier tillers, but at low density.…”

“…A high frequency of defoliation allows greater control of stem elongation, consequently a higher leaf appearance rate that will result in a higher leaf/stem ratio. As a result, the pasture presents better nutritional quality, since the leaf is an organ of the plant that represents the main source of nutrients for ruminants (RODRIGUES et al, 2008). The adoption of an inadequate rest period when managing pastures at high frequency of defoliation and severe defoliation intensity impairs the recovery of organic reserves, which are used in the regrowth process, compromising pasture persistence (GOMIDE et al al., 2002;LUPINACCI, 2002).…”

Eficiência De Utilização De Adubação Orgânica Em Forrageiras Tropicais

“…No 2º corte, apesar do comportamento quadrático, observa-se que nas maiores doses de esterco, a relação folha/colmo diminuiu. O decréscimo da relação folha/colmo, de acordo com Rodrigues et al (2014), compromete a eficiência do pastejo. Rodrigues et al (2008) também verificaram diminuição na relação folha/colmo com o aumento das doses de N e atribuíram este resultado ao maior crescimento das plantas e ao processo de alongamento dos colmos.…”