Características agronômicas, estruturais e valor nutritivo de cultivares de Megathyrsus maximus sob doses de enxofre

Abstract

When improving forage production rates, the first thing to think about is a balanced fertilization in terms of nutrients. The objective was to evaluate the agronomic, structural, composition, in vitro digestibility of dry matter, chemical carbohydrate fractioning and nitrogen compounds of cultivars Zuri, Mombasa, Massai and Tamani under sulfur doses in Orthic Quartizaren Neosoil. The experimental design used was in completely randomized blocks, in a 4x4 factorial, with four cultivars of Megathyrsus mamixum (BRS Massai, BRS Mombaça, BRS Tamani and BRS Zuri) and four doses of sulfur (0, 14, 28 and 42 kg.ha-1) with four replications, totaling sixty-four experimental units. All plots received the same amount of fertilization (100 kg ha-1 in the form of sulfur from Chlorea, potential in the form of superphosphate, and phosphorus in the form of superphosphate, both free of sulfur in its Potassium). There was a significant difference for the variable height of the forage canopy in comparison between the cultivars. There was an effect of the cultivars for a variable tiller population density, where the highest density was observed in the massai and tamani cultivars, followed by zuri and mombaça. In isolation, analyzing the difference doses in each cultivar, there were no height variables, profile population density and leaf index. There was a significant difference for dry mass of leaves, where the cultivars Zuri and Mombasa showed higher values. There was no isolated effect of sulfur doses on Zuri, Massai and Tamani cultivars. As for the leaf:stem ratio, the Massai and Tamani cultivars showed higher values. Note the effect of sulfur doses on the bromatological characteristics, mainly in the protein. The Tamani cultivar showed the highest in vitro dry matter digestibility (702.83 g.kg-1 DM), followed by Zuri (644.84 g.kg-1 DM), Massai (563.24 g.kg-1 DM) ) and Mombasa (511.28 g.kg-1 DM), in addition to having a low lignin content. Sulfur does not influence the yield of Zuri, Massai and Tamani cultivars. However, the cultivar Mombasa is influenced by sulfur fertilization, showing positive responses in relation to the sulfur doses used as variables dry leaf mass, dry mass of dead material, total mass and leaf accumulation rate. It was observed that factors such as cutting height and regrowth periods resulted in composition, that is, more favorable in the proportions of fibrous cultivars.