Propriedades químicas, anatômicas, biomecânicas e composição da lignina do Capim-Tanzânia adubado com nitrogênio e/ou pré-tratamento com fungo da podridão branca

• Ano de defesa: 2014
• Autor(a) principal: Pereira, Vinícius Valim
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Estadual de Maringá; Brasil; Programa de Pós-Graduação em Zootecnia; UEM; Maringá, PR; Centro de Ciências Agrárias
• Palavras-chave em Português: Capim-Tanzânia; Adubação nitrogenada; Manejo de pastagem; Características anatômicas e biomecânicas; Ciências Agrárias; Zootecnia
• Link de acesso: http://repositorio.uem.br:8080/jspui/handle/1/1606

The experiment was carried out at the Iguatemi's Experimental Farm (FEI), located at latitude 23º 25 'S; 51 57 'O, and 550 meters, of the State University of Maringá (UEM), Maringá - PR. The experimental period was from November 2012 to September 2013, conducted in an area of Tanzania grass. The experimental area has a total of 800 m2, divided into 16 paddocks with 50 m2 each , in which it was allocated treatments with applications of nitrogen (N) and potassium (K2O), placed according to the total amount to be applied, starting in November 2012, as: Absence of nitrogen; the lower dose (150 kg ha-1 N) in three applications with 45 days interval each; 300 kg ha-1 of N in 6 applications with 30 days interval each; and 450 kg ha-1 N in 9 applications with 15 days interval each, being used as a source of N the ammonium nitrate, and a source of K2O the potassium chloride, which was applied at 45 days interval on all plots, totaling 80 kg ha-1 K2O. For the accumulation of green mass it was use an iron square with 1 m², with three samples being taken per experimental unit at 30 cm from ground level. It was taken two forage samples to determinate the forage dry matter (DM), and to separate the foraging morphological components, obtaining the leaf blade fractions (LB), pseudostem (PS) and dead material (MM), which were weighed fresh and placed in an oven at 55 ºC. Except for MM, the LB and PS fractions were milled. The following analyzes were performed: neutral detergent fiber (NDF), acid detergent fiber (ADF), total nitrogen (TN), neutral detergent insoluble nitrogen per total nitrogen (NDIN/TN) and acid detergent insoluble nitrogen per total nitrogen (NIDA/TN). The cellulose (CEL) and hemicellulose (HEMI) were obtained calculating the estimates of NDF and ADF. The properties of rupture (stress, tensile strength and rupture energy) of fresh leaf blade and fresh pseudostems were measured in five tillers per plot of each treatment, with the texturometer TA.XT Plus, in which the breaking strength (Newton), tensile strength (N mm-2) and rupture energy (mJ) were calculated. The effect of nitrogen fertilization was evaluated using a regression equation. The effect of the cuts was evaluated using the Tukey test (P <0.05). To analyze the anatomical components, it was cut three leaf blades into 1cm (one centimeter) pieces, in the middle region, and three pseudostems, divided into pseudostem base and apex, putted in glasses and fixed in FAA 70%, and stored until histological preparation. In leaf blade was evaluated the area of the adaxial epidermis (EPada) and abaxial (EPaba), sclerenchyma (SCL), vascular bundle sheath (VBS), vascular bundles (VB) and mesophyll (MES). In pseudostem apex and base were measured areas of the epidermis (EPI), xylem (XYL), phloem (PHL), sclerenchyma (SCL) and mesophyll (MES). To anatomy was evaluated the effect of the N by the regression equation in which it was considered the medium values of each variable response in the first (december of 2012) and fifth cut (july of 2013). The effect of the cuts was evaluated using the average test. Also it was used treatment with P. ostreatus, in summer and winter, to evaluate the reducer sugar (AR), the synthesis of lignocellulosic enzymes: manganese peroxidase (MnP), laccase (LAC) cellulase (CELA) and xylanase (XIL) and monomers of lignin: guaiacyl (G), syringyl (S) and hydroxyphenyl (H) and the phenolic isovanillin aldehyde (I) in the LF and CB. The absence of Nitrogen and the Nitrogen rates (150, 300 and 450 kg N ha-1) represented the major plot, and pretreatment with and without fungus, subplots with four replications. Nitrogen when associated with abiotic factors, may have positive or negative effects on forage quality. The nitrogen provides conditions to improve the digestibility of plants due to a possible change of cell wall components. The lignin, NDF and ADF should not be evaluated isolate to determine the limitation of digestibility components. The age of the cut increases or decreases the effect of nitrogen on pasture, being more pronounced at stations where abiotic factors are better. Nitrogen fertilization provided conditions for reducing the traction of Tanzania grass, correlated to cell wall composition. Nitrogen increased the area of the plant, thereby decreasing its rigidity, further improving the quality of forage. In the anatomy of Tanzania grass, nitrogen reduced the most rigid and difficult to digest structures (XIL, ESC) both at the leaf blade as pseudostem. The anatomical characteristics correlated with the breaking strength, especially the structures of slowly digestion. The effect of cut age is reduced on the anatomical characteristics of Tanzania grass when using the light interception management. The amount of 450 kg ha-1 N had more interesting results to improved Tanzania grass properties. The use of substrates that showed higher nitrogen content accelerated its growth and development, increasing the reducer sugar (AR) and the synthesis of lignocellulosic enzymes in both LF and CB, in summer and winter. Lower contents of the monomer G were found when the fertilizer was increased, in LF, in the summer period, and with the use of fungus, making it easier to hydrolysis and therefore freeing a higher content of cellulose. The monomer I showed the lowest concentrations in all treatments, and showed a decrease with treatments with FPB in CB and in LF. S units tend to be rarer than G, and its presence was reduced by N application. Increased levels of nitrogen promotes further development of the FPB, thus causing further degradation of lignocellulosic material, due to increased production of lignocellulosic enzymes as manganese peroxidase and laccase. Increased levels of nitrogen fertilization causes the decrease of monomers, especially when using the FPB.