Morfogênese e acúmulo de forragem em capim-mombaça submetido a intensidades de pastejo rotativo

• Autor(a) principal: Montagner, Denise Baptaglin
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1679
• topic: Ecofisiologia; Estrutura do pasto; Interceptação de luz; Ecophysiology; Pasture structure; Light interception; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PASTAGEM E FORRAGICULTURA

The objective of this experiment was to evaluate the characteristics and dynamics of morphogenetic accumulation of grass in pastures of grass-mombaça (Panicum maximum, cv. Mombasa) managed under grazing intensities of (height after grazing) rotation, during the period of one year. The experiment was developed at Embrapa Livestock Cutting, September 2005 to April 2007. The grass-mombaça was implanted in an area of 2.25 ha, divided into nine paddocks of 0.25 ha each. The experimental design was randomized complete block with three replications. We evaluated three times of post-grazing: residue of 30 cm during the entire experimental period (30); residue of 50 cm during the entire experimental period (50) and residue of 50 cm during the spring and summer, lowered to 40 cm in the first grazing in the autumn to 30 cm in the next pasture, returning to 50 cm after the first spring following grazing (50-30). The interception of light incident (IL) and the height of the canopy were monitored weekly, including the pre and post- grazing. We evaluated the characteristics and structural morphogenetic of grass, the dynamics of tillering, the masses of forage and morphological components pre - and post- grazing, the accumulation of biomass, the perimeter average touceiras and morphogenic and structural characteristics, according to the age the tiller. Depending on the number and range of grazing variable between pickets and waste, the data were converted into weighted average for five seasons of the year, based on the dates and duration of each cycle of grazing by paddock, and analysed using the model of subdivided parcels in the time, in which the waste were the plots and the seasons, the subplots. We used the GLM procedure of the SAS statistical package, adopting is a significance level of 5%. The time required for the canopy interceptasse 95% of the IL incident determined by the availability of conditions for growth, intervals of grazing variávei. The mass of forage, and the IAF IL's postgrazing were lower (P <0.05) in pastures demoted to 30 cm. We managed pastures with variable residue showed higher (P <0.05) proportions of dead material, in relation to other times post-grazing evaluated and higher proportion of stem (P <0.05) in the summer of 2006/07, when the waste returned to 50 cm. The height pre-grazing consistent with the interception of 95% of IL was 90 cm, and stable during the seasons of the year (P> 0.05). Pastures managed a 50 and 50-30 cm high post-grazing showed higher bodies of pre- grazing forage than those kept at 30 cm of residue (P <0.05), although these have made 60% of the mass of leaf blades forage on that occasion. Changes in the structure of the canopy due to the large range of grazing between autumn and spring 2006 increased the mass of stems and dead material (P <0.05), and corroborated by the high Filocrono DVF (P <0.05) in the pre - grazing of spring. Already the largest TApF and TAlF (P <0.05) observed in the summer of 2006/07 justify the high rates of accumulation of forage, mainly of leaf blades at the time of the year, when conditions for growth are favorable. The lowering of the residue of 50 to 30 cm during the autumn changed the structure of the pasture, so that increases were observed in TAlF, the rate of appearance of tillers blocks and in the proportion of stem and decrease in the proportion of dead material in the pre-grazing (P <0.05), in the summer of 2006/07, when the waste returned to 50 cm high (first grazing of spring). Pastures managed with time post-grazing variable, ie demoted from 50 to 30 cm in the fall, returning to 50 cm in the first of spring grazing, have structural changes capable of improving the force of regrowth, which may be important to maximize the use of forage species in the system of production, ensuring their persistence and perennation.