Morfogênese, características estruturais, acúmulo e composição química da forragem do capim-estrela manejado sob estratégias de lotação intermitente.

Abstract

The aim of this study was to evaluate the morphogenesis, the structural characteristics, the accumulation and chemical composition of forage of the stargrass pastures (Cynodon nlemfuensis cv. Florico), managed with two light interceptions in pre-grazing (90 and 95% of LI), and two stubble height in post-grazing (20 and 30 cm) during the autumn, winter and spring of 2012 and summer of 2013 seasons. The experiment was carried out at Pesagro - Rio experimental area, Seropédica - RJ, in 16 paddocks with 300 m 2 each, arranged in a randomized complete block design, in a 2x2 factorial arrangement, with four replications. The morphogenesis and structural characteristics of the canopy and forage accumulation were evaluated from the tissue flow. The structural characteristics, the forage accumulation, the forage harvest efficiency and the chemical composition also were evaluated from quantitative sampling (harvest). The data were analyzed by SAS® PROC MIXED, 9.2 version for Windows, and the means of the treatments estimated by LSMEANS and compared by PDIFF(p<0.05). The morphogenetic characteristics varied with the interaction between light interception, stubble height and seasons, and the best grow conditions promoted higher TApF, TAlLF and TAlC and lower FIL and LLF, who determined higher number of FVP and CMLF, consequently, higher IAF, TCLF, TCC, TC, TALF and TALLF in summer than other seasons. The management with 90% LI and 20 cm provide highest TApF, TAlLF and TAlC, with highest growth rates and forage accumulation in all seasons. The structural and productive characteristics of stargrass were altered by the light interception and stubble height, and the forage harvesting efficiency was altered only by the light interception. The high stem production reflected in low leaf blade:stem ratio, with advantage for the management with 95% LI and 30 cm in autumn and winter. The lack of a defined pattern of the morphological components variation may be due to both the growth habit and morphological structure of the stargrass, as well the levels of light interception tested. The light interception and stubble height jointly affect the forage chemical composition, because to alter the plants physiological stage and the proportion of forage removed by animals, so that grazing with 90% LI association with 30 cm stubble height provide the best forage chemical composition during the seasons.