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.

Avaliação das características estruturais do capim-braquiária em pastagens adubadas com nitrogênio nas quatro estações do ano

Abstract: This trial was carried out from November 2001 to November 2002, aiming at the evaluation of the effects of nitrogen fertilization upon the tiller demography and forage biomass in Brachiaria decumbens cv. Basilisk pastures fertilized with nitrogen and subjected to the same grazing height. The treatments consisted of four nitrogen rates (75, 150, 225 and 300 kg/ha.yr.) applied before the beginning of the experimental evaluations, which were performed during the Summer, Fall, Winter and Spring, 2002. A completely randomized block experimental design was used with two replications. Seasons and nitrogen rates affected grass tiller population density and forage biomass. The population density of alive and vegetative tillers increased linearly, while that of the dead tillers decreased linearly with the N rates. Forage biomass increased linearly with nitrogen fertilization, whereas the population density of reproductive tillers were not affected by nitrogen fertilization. The alive tiller population density, vegetative and reproductive, leaf biomass, stem and green matter of the Brachiaria decumbens varied among the seasons, with lower values in Winter.

Genetic improvement of sugar cane for bioenergy: the brazilian experience in network research with RIDESA

Abstract: In this paper, it is presented RIDESA's model for sugar cane breeding to ethanol, and its scientific, technological and human resources training contributions. RIDESA is an inter-university network for the development of sugar cane industry in Brazil, and was formed by a technical cooperation agreement between ten public universities. The model of network management is presented in this study, which involves, among other things, the public-private partnership (Universities-Mills) for the development of cultivars. RIDESA has produced 59 cultivars since 1990 and is now responsible for 59% of the total area cultivated with this plant in Brazil. In the last five years, 286 agronomists were trained in breeding programs at universities that comprise RIDESA. In this same period, the network formed 35 professors, 24 doctors and 7 post-docs in researches with this crop. It is also presented a conceptual approach on methods of sugar cane breeding involving families and genome-wide selection.

Potencial de espécies utilizadas como adubo verde no manejo integrado de plantas daninhas

Abstract: O presente trabalho foi conduzido na Estacao Experimental da Universidade Federal do Tocantins, Gurupi-TO, Brasil. O experimento foi instalado com o objetivo de avaliar durante 60 dias, em campo, a interferencia de oito especies utilizadas frequentemente como adubos verdes (Mucuna aterrima, Mucuna pruriens, Crotalaria ochroleuca, Crotalaria spectabilis, Canavalia ensiformis, Cajanus cajan, Pennisetum americanum e Sorghum bicolor, hibrido BR304) sobre a comunidade infestante. As especies de plantas daninhas mais frequentes na area do experimento foram: Digitaria horizontalis, Hyptis lophanta e Amaranthus spinosus. Foram realizadas amostragens aos 15, 30, 45 e 60 dias apos a formacao da cobertura, utilizando um quadrado de amostragem equivalente a 0,25 m2. As plantas daninhas foram devidamente identificadas, coletadas, secas e pesadas. O delineamento experimental utilizado foi inteiramente casualizado e constou de nove tratamentos, com quatro repeticoes cada. Verificou-se que as especies C. spectabilis, S. bicolor, C. ochroleuca, M. aterrima e M. pruriens reduziram significativamente o numero e o peso da materia seca da populacao das plantas daninhas avaliadas (D. horizontalis, H. lophanta e A. Spinosus), principalmente as duas ultimas, enquanto P. americanum mostrou-se a menos eficiente nesse aspecto.

Phylogeny, identification and pathogenicity of the Botryosphaeriaceae associated with collar and root rot of the biofuel plant Jatropha curcas in Brazil, with a description of new species of Lasiodiplodia

Abstract: The global expansion of cultivation areas of Jatropha has contributed to the emergence of various diseases. Currently in Brazil, the occurrence of a new disease has been reported that not only reduces the productivity but also causes the death of Jatropha. This disease is associated with collar and root rot of plants. From morphological and phylogenetic studies (based on Internal Transcribed Spacers, β-tubulin and Translation Elongation Factor 1-α sequences), nine species of Botryosphaeriaceae were identified. These species include Lasiodiplodia egyptiacae, L. pseudotheobromae, L. theobromae, Macrophomina phaseolina, Neoscytalidium hyalinum and four Lasiodiplodia spp. that are proposed as new species (L. euphorbicola, L. jatrophicola, L.macrospora and L. subglobosa). All the species in this study, except M. phaseolina, are pathogenic. The results show that root rot of physic nut plants is caused by complex pathogens. This study provides new information for future studies of disease management, quarantine programs and, especially, the development of resistant varieties for collar and root rot disease in J. curcas.