Universidade Federal de Viçosa

About: Universidade Federal de Viçosa is a education organization based out in Viçosa, Brazil. It is known for research contribution in the topics: Population & Biology. The organization has 16012 authors who have published 26711 publications receiving 353416 citations.

Climate change impacts on sugarcane attainable yield in southern Brazil

Abstract: This study evaluated the effects of climate change on sugarcane yield, water use efficiency, and irrigation needs in southern Brazil, based on downscaled outputs of two general circulation models (PRECIS and CSIRO) and a sugarcane growth model. For three harvest cycles every year, the DSSAT/CANEGRO model was used to simulate the baseline and four future climate scenarios for stalk yield for the 2050s. The model was calibrated for the main cultivar currently grown in Brazil based on five field experiments under several soil and climate conditions. The sensitivity of simulated stalk fresh mass (SFM) to air temperature, CO2 concentration [CO2] and rainfall was also analyzed. Simulated SFM responses to [CO2], air temperature and rainfall variations were consistent with the literature. There were increases in simulated SFM and water usage efficiency (WUE) for all scenarios. On average, for the current sugarcane area in the State of Sao Paulo, SFM would increase 24 % and WUE 34 % for rainfed sugarcane. The WUE rise is relevant because of the current concern about water supply in southern Brazil. Considering the current technological improvement rate, projected yields for 2050 ranged from 96 to 129 t ha−1, which are respectively 15 and 59 % higher than the current state average yield.

Esterification of Oleic Acid for Biodiesel Production Catalyzed by SnCl2: A Kinetic Investigation

Abstract: Abiney L Cardoso, Soraia Cristina Gonzaga Neves and Marcio J da Silva * Departament of Chemistry, Federal University of Vicosa, Vicosa, Minas Gerais, Brazil, 36570-000 * Author to whom correspondence should be addressed; E-Mail:silvamj2003@ufvbr Received: 5 August 2008; in revised form: 16 September 2008 / Accepted: 17 September 2008 / Published: 24 September 2008 Abstract: The production of biodiesel from low-cost raw materials which generally contain high amounts of free fatty acids (FFAs) is a valuable alternative that would make their production costs more competitive than petroleum-derived fuel Currently, the production of biodiesel from this kind of raw materials comprises a two-stage process, which requires an initial acid-catalyzed esterification of the FFA, followed by a base-catalyzed transesterification of the triglycerides Commonly, the acid H

Características morfogênicas e estruturais do capim-braquiária em pastagem adubada com nitrogênio avaliadas nas quatro estações do ano

Abstract: Este experimento foi realizado com o objetivo de avaliar o efeito da adubacao nitrogenada sobre as caracteristicas morfogenicas e estruturais de Brachiaria decumbens sob pastejo. Os tratamentos consistiram da aplicacao de quatro doses de nitrogenio (75, 150, 225 e 300 kg/ha.ano) antes do inicio das avaliacoes experimentais, realizadas em 2002 durante as estacoes de verao, outono, inverno e primavera. Utilizou-se o delineamento em blocos completos casualizados, com duas repeticoes. A taxa de alongamento de folha, o comprimento final da folha, o indice de area foliar e as porcentagens de colmo e de lâmina foliar aumentaram linearmente, enquanto a porcentagem de material morto decresceu com a adubacao nitrogenada da Brachiaria decumbens sob pastejo. Nao foi constatado efeito da adubacao nitrogenada sobre o numero de folhas vivas, de folhas emergentes e de folhas totais e as taxas de alongamento do colmo e de senescencia foliar. A taxa de alongamento de folha e de colmo, o numero de folhas vivas, o comprimento final da folha, o indice de area foliar e a porcentagem de lâmina foliar e de colmo de Brachiaria decumbens variaram entre estacoes do ano, apresentando valores menores no inverno.

Estimating the effects of population size and type on the accuracy of genetic maps

Abstract: Based on simulation studies, it was shown that the type and size of experimental populations can exert an influenceon the accuracy of genetic maps. A hypothetical genome map (one chromosome with nine equidistant molecularmarkers) was generated for the following population types: F 2 with dominant and co-dominant markers, backcross-ing, recombinant inbred lines (RIL) and double-haploid. The population sizes were 50, 100, 150, 200, 500 and 1000individuals and 100 simulations were made for each population. The inaccuracies of the populations with the lowestnumber of individuals were shown by inversions in the order of the markers and the establishment of more than onelinkage group in up to 38% of the simulations, depending on the population type. Stress and variance values of thedistancesbetweenadjacentmarkersweresignificantlyreducedwiththeincreasedsizeofthepopulation.Moreaccu-rate maps were obtained for the co-dominant F 2 and RIL whereas the maps for the dominant F 2 population were lessaccurate. The higher the number of individuals, the more precise was the map. In all populations, a total of 200 indi-viduals were considered as being sufficient for the construction of reasonably accurate genetic maps. Although thispaper deals with plant populations this approach is equally applicable to other organisms.