Rosana Cristina Pereira

Características produtivas e qualitativas de ramas e raízes de batata-doce

A batata-doce e uma hortalica que se destaca pela versatilidade no uso, podendo ser empregada tanto na alimentacao humana como animal. Seu cultivo e relativamente facil e barato, o que, juntamente com sua adaptabilidade a variadas condicoes edafo-climaticas, viabiliza sua producao pelos agricultores familiares. Objetivou-se avaliar a producao de massa verde e massa seca da parte aerea para utilizacao na alimentacao animal e a produtividade e a qualidade das raizes tuberosas de clones de batata-doce para utilizacao na alimentacao humana. O delineamento experimental utilizado foi em blocos casualizados, com doze clones e quatro repeticoes. Foram avaliados clones de batata-doce pertencentes ao banco de germoplasma da UFVJM juntamente com as cultivares comerciais Brazlândia Roxa e Brazlândia Rosada, colhidos aos seis meses apos o plantio. Foram avaliadas a producao de massa verde e massa seca da parte aerea e a produtividade e qualidade das raizes tuberosas. O clone BD-45 destacou-se na producao de massa verde, producao de massa seca e nas produtividades total e comercial de raizes com valores de 19,7; 3,3; 32,9 e 29,5 t ha-1, respectivamente. A maioria dos genotipos avaliados apresentou raizes com formato proximo ao ideal para comercializacao e boa resistencia a insetos de solo com valores de notas proximos a 2,0. Foram observadas diferencas significativas entre os genotipos para os teores de amido e acucares totais e redutores. Os genotipos apresentaram composicao centesimal semelhante, exceto para o teor de cinzas. Os clones BD-67 e BD-56 apresentaram teores de cinzas mais elevados que o Cambraia, e semelhantes aos demais clones.

Composição lignocelulósica e isótopica da vegetação e da matéria orgânica do solo de uma turfeira tropical: I - composição florística, fitomassa e acúmulo de carbono

Soil organic matter (SOM) is one of the major reservoirs of carbon on Earth and is one of the key contributors to the carbon cycle. Peatlands are natural accumulators of organic matter commonly derived from decomposing plant residues in water-saturated environments, and represent an initial stage of a much longer pedogenic pathway leading to carbonification. The soil biomass markedly influences the global carbon cycle, accounting for approximately 85 % of all carbon on the Earths surface. Plant tissues are mainly composed of lignin, cellulose and hemicelluloses, representing as much as 85 % of their dry biomass. Plants usually discriminate carbon differentially, according to their photosynthetic cycle (C3, C4 and CAM). The vegetation of the bogs in the southern domain of Serra do Espinhaco (SdEM; Brazil) consists mostly of moist grassland (CLU) and semideciduous forest (FES), with species of both C3 and C4 cycles. This study was designed to discriminate the contribution of these two vegetation types to the accumulation of soil organic matter by an analysis of the biomass and of the lignocellulosic and carbon isotopic composition and SOM. The studied peat is located in SdEM and covers an area of 81.75ha. Three 0.5x0.5m plots were marked per vegetation type, to delimit the sampling areas, for which biomass of CLU and FES were estimated. All plants per plot were cut and adequately stored to preserve as much of their fresh characteristics as possible. To characterize the isotopic and lignocellulosic composition of the vegetation, the species of each vegetation type were systematically identified according to their main botanic characteristics. Soil samples were collected at three representative sites under each vegetation type, at intervals of 5 cm, down to a depth of 50 cm. Cellulose and lignin were extracted from leaves of 15 dominant species and 60 peat samples, to quantify and determine the values of δ13C and δ15N. The 14C was determined at three depths under CLU and FES. The biomass production under FES was much higher than the biomass production under CLU. The isotopic signals and lignocellulosic composition of the vegetation and SOM confirmed that this peat was originated by the deposition of organic matter from the colonizing vegetation. The vertical growth and the carbon storage rates are much higher under FES than under CLU.

Composição lignocelulósica e isótopica da vegetação e da matéria orgânica do solo de uma turfeira tropical: II - substâncias húmicas e processos de humificação

Much of the organic matter of a typical peat consists of humic substances, mainly formed via humification of organic residues, decomposed by soil microorganisms, and by the polymerization of organic compounds to functional macromolecules, which are normally more resistant to degradation. The fundamental pathways governing the humification of soil organic matter (SOM) are not well understood so far, and most available data about the identified chemical precursors of humic substances and the main chemical routes by which they are transformed in the peat environment are still poorly understood. What is clear is that all routes involve lignin as a chemical intermediate. Stable isotopes (δ13C, δ15N) can be used to trace humification processes of the soil organic matter (SOM), by identifying their precursors. The purpose of this study was to compare the isotopic composition of vegetation materials from the two bog vegetation types that colonize a tropical highland peatland: moist grassland (CLU) and semideciduous forest (FES), based on the isotopic composition of humic substances of SOM. The whole area of the studied peatland occupies 81.75 ha. To identify the isotopic and lignocellulosic vegetation composition, materials of the dominant species of each vegetation type were sampled. Soil samples were collected from three representative sites per vegetation type, at intervals of 5 cm from the surface down to a depth of 50 cm. The humic substances were isolated from these samples; signals of δ13C and δ15N were determined for the humic fractions. The lignin and and δ13C values were higher in vegetation and SOM under FES than in SOM under CLU. Humin contents were high in SOM under both vegetation types; the levels of humic acids were higher in SOM under CLU than in FES; fulvic acid contents were higher in SOM under FES than CLU. The 13C values for lignin were highly similar to those for humic acids and fulvic acids. Variations in the lignocellulosic composition of the species that colonize the CLU and FES promote different rates and SOM humification products.

Avaliação de silagens de ramas de batata-doce

O presente trabalho teve como objetivo selecionar clones de batata-doce com potencial para uso na alimentacao animal. O experimento foi conduzido em blocos ao acaso, com 11 clones e quatro repeticoes. Os clones avaliados fazem parte do banco de germoplasma da Universidade Federal dos Vales do Jequitinhonha e Mucuri, sendo: BD-06, BD-25, BD-15, BD-38, Cambraia, BD-31-TO, BD-67, BD-45, BD-42, BD-54 e a cultivar Brazlândia Rosada. Nas ramas coletadas do experimento foram avaliados o teor de materia seca e as produtividades de massa verde e massa seca. Nas silagens de ramas foram avaliados o pH e os teores de materia seca (MS), proteina bruta (PB), fibra em detergente neutro (FDN), fibra em detergente acido (FDA), nutrientes digestiveis totais (NDT), fosforo, calcio e sodio. Nao houve diferenca significativa para a produtividade de massa verde e de massa seca das ramas entre os clones de batata-doce. As silagens produzidas caracterizam-se como volumosos de boa qualidade, apresentando teores satisfatorios de proteina bruta (11,59%), FDN (31,98 a 39,68%), FDA (29,65 a 35,45%) e NDT (62,90 a 66,91%), comprovando o potencial de utilizacao das ramas da batata-doce na forma de silagem.

Produção de silagem, composição bromatológica e capacidade fermentativa de ramas de batata-doce emurchecidas

The variation in the availability of forage throughout the year and the need to use low-cost food for ruminants contributed to an increase in the search for new food alternatives. This study aimed to evaluate the yield of the dry mass of vines and the effect of wilting on the chemical composition and fermentative capacity of sweet potato vines for silage production. The evaluated genotypes were BD-08, BD-23, BD-25, BD-31TO, BD-38, BD-43 and Brazlândia Roxa, using a 7x2 factorial arrangement (genotype x wilted vines or not), in a randomized block design, with four replications. We determined the dry matter yield (PMS) and dry matter (MS), crude protein (PB), neutral detergent fiber (FDN), acid detergent fiber (FDA), cellulose, hemicellulose, lignin, ash, water soluble carbohydrates (CS), acid detergent insoluble nitrogen (NIDA), buffering capacity (CT) and fermentative capacity (CF) of fresh and wilted vines. The MS of vines ranged from 4.2 to 7.9 t ha-1, with emphasis on BD-25, BD-08 and BD-23 with yields higher than 7.0 t ha-1. Wilting promoted increase in MS (15.7 to 25.7%), PB (11.0 to 11.9%), FDA (29.2 to 41.7%), lignin (8.6 to 15.5%), cellulose (19.3 to 24.3%), ash (8.9 to 10.0%) and NIDA (9.7 to 32.8%), and reduced levels of CS (15.0 to 7.6%), making the wilted branches of poorer quality. Wilting did not affect the CF of the vines (average 37.2) and promoted an increase in FDN differently for each genotype. The highest levels of MS in wilted vines offset the lower level of CS, making similar the CF of vines.The sweet potato vines of all genotypes presented high potential for silage.

Rehabilitation with forage grasses of an area degraded by urban solid waste deposits

Dry matter yield and chemical composition of forage grasses harvested from an area degraded by urban solid waste deposits were evaluated. A split-plot scheme in a randomized block design with four replicates was used, with five grasses in the plots and three harvests in the subplots. The mineral content and extraction and heavy metal concentration were evaluated in the second cut, using a randomized block design with five grasses and four replicates. The grasses were Brachiaria decumbens cv. Basilisk, Brachiaria ruziziensis, Brachiaria brizantha cv. Marandu and cv. Xaraes, and Panicum maximum cv. Tanzânia, cut at 42 days of regrowth. The dry matter yield per cut reached 1,480 kg ha-1; the minimum crude protein content was 9.5% and the average neutral detergent fiber content was 62.3%. The dry matter yield of grasses was satisfactory, and may be an alternative for rehabilitating areas degraded by solid waste deposits. The concentration of heavy metals in the plants was below toxicity levels; the chemical composition was appropriate, except for phosphorus. The rehabilitated areas may therefore be used for grazing.

Yield and quality of wilted sweet potato vines and its silages

Sweet potato is widely used for human consumption, but has also potential for its use in animal feeding. In this study we evaluated yield and quality as forage of wilted vines of various sweet potato genotypes and selected the most suitable for silage. Fifteen genotypes were evaluated (BD-31TO, BD-26, BD-13, BD-17, BD-22, BD-24, BD-54, BD-56, BD-69, BD-43, BD-44, BD-46, BD-52, BD-35, and cultivar Brazlândia Rosada), in a randomized complete blocks design, with three replications. At harvest we determined the yield of fresh matter and subsequently dry matter of vines. After 190 days of ensilage, we determined the concentrations of dry matter, crude protein, neutral and acid detergent fiber, lignin, ash, soluble carbohydrates in both vines and its silages; buffering and fermentative capacities of vines, and pH of silages. Genotypes BD-13, BD-17, BD-54, BD-56, BD-43, BD-44, BD-46, and BD-52 showed medium to high yield of fresh and dry matter. There were significant differences among genotypes in all studied bromatological characteristics, except for carbohydrate concentrations in wilted vines and their silages. Considering wilted vines, genotypes BD-26, BD-13, BD-56, BD-46, BD-35 and cultivar Brazlândia Rosada were those with the most suitable bromatological composition for animal feeding. Genotype BD-56 was the most appropriate for silage production.

Structural and productive characteristics of Marandu and Xaraés grasses fertilized at different times after harvesting

The objective of this study was to assess the effect of applying N and K2O at different times after harvest on the structure and production characteristics of Marandu and Xaraes cultivars of Brachiaria brizantha. Two greenhouse 4 × 2 factorial experiments using a randomized block design with eight treatments and four replicates were carried out. In experiment 1, the plants in pots were fertilized weekly with 50 mg/dm3 of N and K2O until a week before a uniformity cut, for a total of four applications. After cutting, plants were fertilized with 50 mg/dm3 of N and K2O at 0, 3, 6, and 9 days. Cultivars were evaluated after 44 days of regrowth. In experiment 2, a single 50 mg/dm3 dose of N and K2O was applied a week before the uniformity cut, and 100 mg/dm3 of N and K2O were applied at 0, 4, 8, and 12 days after cutting; cultivars were evaluated after 39 days of regrowth. In experiment 1, the leaf/stem ratio and dry matter yield were influenced by the time at which fertilizers were applied. In the second experiment, the total number of leaves, expanded leaves, dead leaves, and the leaf lamina accumulated length and dry matter production were influenced by the time at which fertilizers were applied. Marandugrass had more leaves and tillers than cv. Xaraes, which, in turn, had greater height, dry matter yield and regrowth vigor. Applying nitrogen and potassium fertilizer immediately after cutting improves the structural characteristics, while the dry matter yield is maximized by applying fertilizers immediately after cutting by using lower doses of N, or at 4.5 days after cutting by using higher doses of N.