Desinfestação de erva-mate in vitro.

EVINCI. Resumo 016

An Ecophisiological Proposal to Manage Natural Grasslands: A Long Term Trial

Natural grasslands on Southern Brazil comprise the so called “Rio de La Plata Grasslands” in South America. They are an important fodder source for ruminant pastoral systems and contribute to regional ecosystem services. Strength of these grasslands is its floristic diversity that poses a dilemma to farmers: how to choose management protocols that could be applied for hundreds of species. We propose to use a functional ecophysiological approach based on groups of grasses, the most abundant on aerial biomass of this natural grasslands. We clustered the most frequent grasses in two groups based on its leaf traits (leaf dry matter content and specific leaf area). These traits are functional clues to growth rhythms and nutritive value that could separate grasses in “resource capture” and “resource conservation” groups, both important for forage production and ecosystem services. Evaluating the most frequent grasses in each group we found they have an average of 375 degree-days, for “resource capture” and 750 degree-day for “resource conservation” groups, as its leaf elongation duration. So we evaluated a rotational grazing system based on this morphogenic trait for beef heifers rearing on natural grasslands from 2010 to 2019. We chose these experimental animals, as a model by its nutrient requirements and relevance for regional rearing and breeding systems. Our results indicate an average daily gain that is adequate to reach mating age and weight targets (0,3 kg/heifer/day to mate at 24 months) and allowed a higher stocking rate and gain per area when compared to regional standards (1,100 kg of live weight/ha and 370 kg/ha versus 600 and 70 kg/ha). All this animal performance was obtained without changing floristic diversity and also enhancing ecosystem services as CO2 sequestration. We concluded that this approach could allow farmers to conciliate the dilemma of production and conservation in pastoral ecosystems

Pasture Dynamics after Sodseeding Cool Season Species with or without Glyphosate in Subtropical Natural Grasslands

This trial was conducted to evaluate vegetation dynamics of natural grasslands fertilized and sodseeded with the cool season species Italian ryegrass (Lolium multiflorum), white clover (Trifolium repens) and birdsfoot trefoil (Lotus corniculatus) with or without glyphosate. Treatments that included herbicide spraying on natural vegetation caused a substitution of perennial grasses by undesirable species, and did not show a significant contribution of introduced species. Andropogon lateralis, Paspalum notatum, Paspalum dilatatum and Paspalum plicatulum almost disappeared, and were replaced by Chaptalia nutans and Apium spp, among others

Conteúdo de n-alcanos em gramíneas nativas do bioma Pampa.

SIEPE

Eficiência do método de desinfestação de explantes de Ilex paraguariensis Saint hilaire por cloreto de mercúrio.

EVINCI. Resumo 009

An Approach to Evaluate Soils Influence on Floristic Composition of Natural Grasslands

This trial aims to evaluate floristic composition of most abundant species in three soil typical of Pampa biome on Brazil. The survey was held at Maronna Fundation located on southern Alegrete municipality, on Rio Grande do Sul, Brazil’s state. Regional climate belongs to Koeppen’s Cfa class. Soil types were shallow basalt (Psamments e Orthents), deep basalt (Vertisols) and sandy soil (Acrisols or Ultisols). Floristic composition were evaluated by visual ranking of aerial biomass of the major species (transformed to kg of dry matter per hectare), calibrated by cuts at ground level, according to field procedures of BOTANAL method. Grasses were clustered according to functional groups based on its leaf traits as proposed by Cruz et al. (2010). This approach proposed a ranking of grasses that ranges from its increasing leaf dry matter, and decreasing specific leaf area, from A to C groups. Total forage mass varied according to soil type. Contribution of A, B and C groups on total forage mass range from 40 to 60 %. Paspalum notatum, from B group, were found on the three soils, being more abundant on sandy and shallow basalt soils. Andropogon lateralis, from C group, was dominant on deep basalt soils, while Axonopus affinis, from A group, has higher biomass contribution on the same soil. We concluded that soil type affected floristic composition, even with this simplified diagnosis criteria

Vegetation composition and forage mass in grassland with a double structure under two winter grazing regimes.

Remnant areas of Pampas grassland have a distinct double structure. Efficiency of livestock farming on these grasslands depends on practices that are synchronized with natural variation. This study examined the changes in vegetation composition and forage mass during winter to understand the effects of grazing methods in a natural pasture with a double structure that was grazed by heifers

Vegetation Dynamics of Campos Under Grazing/Fire Regimes in Southern Brazil

Natural grassland vegetation in Southern Brazil, known as campos, has most likely evolved under a disturbance regime that included fire and grazing (Pillar et al., 1997). Nowadays, the composition of the vegetation of campos is grazing- and fire-dependent (Boldrini et al., 1997). Its importance can be evaluated by the fact that it represents 37 % of the state’s area and provides 77 % of the slaughtered cattle at Rio Grande do Sul (Barcellos et al., 2002). The objective of this experiment was to evaluate the vegetation dynamics of campos under grazing/fire regimes in order to explore the resilience of the vegetation under the regimes studied

Análise fractal do padrão espacial de plantas em pastagem.

ABSTRACTThe use of fractal analysis was evaluated as a tool in the determination of grazing patterns in natural grasslands submitted to different managements. The treatments tested in Santa Maria were grazing with burning, grazing without burning, exclusion with burning and exclusion without burning. In Bagé, the evaluated treatments were natural pasture and introduction of ryegrass, white clover and birdsfoot trefoil in a natural grassland. The characterization of the floristic composition of the pasture was performed by the BOTANAL method. The pasture diversity was calculated by Shannon (H') and Evenness (J) indexes. The fractal dimension information was calculated by regression between H'(ε) and ε natural algorithm, with the line?s slope being the fractal dimension information. Shannon and Evenness indexes showed dependence on the sample area, where the highest floristic diversity and homogeneity of the distribution frequency of plants between species were observed in the sample range of 0.87 to 1.03m2. The fractal dimension can be a tool in determining patterns in the plant community on the reduced grazing scale. The limitation of the use of this technique for reduced scales is the need for a greater number of repetitions.Keywords: burn, diversity, evenness, grazing, shanno