Estrutura e produção do capim-tifton 85 sob duas intensidades e duas frequências de desfolhação com ovinos

Abstract

The process of defoliation, composed of intensity and frequency, interfere in the growth pattern, the structural and productive characteristics of forage crops. Knowledge of these answers is essential to the use of grasses in pastures. This study was conducted to evaluate the structural and productive characteristics on Tifton 85 grass under two frequencies and two intensities of defoliation, managed under intermitente stocking with sheep. The experiment was conducted at Núcleo de Ensino e Estudo em Forragicultura – NEEF/DZ/CCA/UFC, Fortaleza, Ceara, from March to December of 2015, in a area of Tifton 85 grass. The treatments were combinations between two frequencies (85 and 95% of interception of photosynthetically active radiation - IPAR) and two intensities of defoliation (1.0 and 1.8 of residual leaf area index - LAI), in a 2x2 factorial arrangement and a completely randomized design, with four replications, totaling 16 experimental units of 40 m². The grazing was carried out by Morada Nova sheep, managed under intermittent stocking using the mob- stocking technique. For IPAR and LAI evaluations a canopy analyzer equipment was used - AccuPAR LP-80 (DECAGON Device). The following variables were evaluated in the post and pre-grazing: interception of photosynthetically active radiation, leaf area index, canopy height and tiller density. It was evaluated also the total residual forage biomass and its components and the total accumulation of forage and its components. It has been found lower (P<0,05) rest period in pastures under management 85x1.8 and higher in pastures with 95x1.0. The residual height was higher (P<0,05) in pastures under 95x1.0 and 85x1.8 management compared to those under 85x1.0 management. Pastures with frequency 95% of IPAR had higher pre-grazing height (P<0,05) than pastures with 85% of IPAR. There was a reduction (P<0,05) in the total and aerial tiller population pre-grazing in the pastures managed with 95% of IPAR and residual LAI 1,0. The green leaf blade accumulation was higher (P<0,05) in pastures managed under 95x1.0, however, there was also greater (P<0,05) accumulation of green stem and dead forage in these pastures compared to 85x1.0 treatment. Tifton 85 grass managed under 85% IPAR and residual LAI 1.0 presented better structure and morphological composition for grazing with sheep.