Deise Ferreira Xavier

Avaliação agronômica de híbridos interespecíficos entre capim-elefante e milheto

O objetivo deste trabalho foi avaliar o comportamento agronomico de hibridos entre capim-elefante (Pennisetum purpureum Schum.) e milheto (P. glaucum (E.) Leek), a fim de determinar seu potencial para o melhoramento da forragem e a selecao de hibridos para futuras avaliacoes. Foram utilizadas 12 cultivares de milheto e 11 clones de capim-elefante, cruzados em esquema de dialelo parcial. As 132 combinacoes hibridas, alem de duas testemunhas, foram avaliadas em experimentos em blocos casualizados, com tres repeticoes. Anotaram-se dados de producao de materia seca, altura de plantas, porcentagem de materia seca, relacao entre folha e caule e de qualidade da forragem (porcentagem de proteina bruta, porcentagem de fibra em detergente neutro e acido e digestibilidade in vitro da materia orgânica). Foi verificada existencia de variabilidade entre os hibridos interespecificos de capim-elefante e milheto, na maioria das caracteristicas. A superioridade de alguns hibridos, em relacao as testemunhas, demonstra o potencial do cruzamento entre P. purpureum e P. glaucum para a obtencao de cultivares melhoradas. Considerando-se tanto caracteristicas de producao como de qualidade da forragem, os melhores hibridos avaliados foram 108 (F91-2-5 x M-60), 53 (F93-4-2 x M-27), 35 (F94-28-3 x M-42), 36 (F94-28-3 x M-60) e 4 (F92-101-2 x M-35).

Avaliação de gramíneas forrageiras na região sul de Minas Gerais

experiments were undertaken in the South region of Minas Gerais State, Brazil, to evaluate the yield potential of forage grasses. In experiment 1, the following species, considered as having low nutritional requirements, were evaluated: Andropogon gayanus, Kunt; Brachiaria brizantha, Stapf; Brachiaria decumbens, Stapf; Brachiaria ruziziensis, Germain Evrard; Brachiaria humidicola (Rendle) Schweickt and Melinis minutiflora, Beauv. In experiment 2, the species considered as having medium and high nutritional requirements, that is: Setaria sphacelata (Schum.); Hemarthria altissima, (Poir.) Stapf; Chloris gayana, Kunt; Cynodon nlemfuensis, Vanderyst var. nlemfuensis; Hyparrhenia rufa, (Ness) and the cultivars Panicum maximum, Jacq.: Tobiata, Green Panic and Makueni were evaluated. The experimental design used was randomized blocks with three replications. Rates of lime and of fertilizers for both establishment and maintenance differed between experiments. Each grass was evaluated for the following atributes: forage yield and crude protein content in the dry and wet season and ground cover. In experiment 1, the grasses with outstanding performance were B. brizantha, B.decumbens and A. gayanus, while in experiment 2 the species having the highest forage yield potential were: S. sphacelata, P. maximum cv. Tobiata.

Potencial forrageiro de novos clones de capim-elefante

The objective of this experiment was to evaluate the forage potential of new selected clones of elephantgrass. The evaluation was conducted at the Dairy Cattle Research Centre - EMBRAPA, Coronel Pacheco, Minas Gerais, for two consecutive years. Twenty selected clones obtained by the elephantgrass breeding program were evaluated, and two traditional cultivars Cameroon and Taiwan A -146 were used as control. The experimental procedure was a randomized block design with four replicates. The fertilization for both establishment and maintenance was applied according to the soil chemical analysis and elephant grass nutritional requirements. Significant differences among the clones were observed regarding to forage production potential, leaf:stem ratio, and aerial and basal tillering. The majority of the evaluated new clones were superior to the traditional cultivars Cameroon and Taiwan A-146 with relation to dry matter production during the dry and rainy periods. Crude protein content in the forage did not differ among the new clones and the control cultivars (Cameroon and Taiwan A-146), during both dry and rainy seasons. The clone F 27-01, released as elephant grass cultivar Pioneiro, was superior for the most evaluated agronomic traits.

Características produtivas e nutricionais do pasto em sistema agrossilvipastoril, conforme a distância das árvores

The objectives of this work were to evaluate the effects of trees arranged in rows on yield and nutritional characteristics of Urochloa decumbens and to identify the average distance in which there is a better use of moderate shading in an agrisilvipasture system. The treatments consisted of distances from measure points to tree rows (0, 3, 6, 9, 12 and 15 m) and were distributed in randomized blocks, with four replicates. The tiller density, forage mass, forage accumulation rate and chemical composition of pasture were evaluated. The tiller density, forage mass and rates of forage accumulation increased with the distance from tree rows, reaching the highest values of 392 tillers m-2, 1,347 kg ha-1 and 30.1 kg ha-1 per day, respectively, at 9.1, 10.4 and 8.8 m of distance. The contents of the neutral detergent fiber did not vary with distance, while the acid detergent fiber and lignin content varied, but without a clear pattern of response. The crude protein contents reduced quadratically with distance from tree rows and had the highest values under trees (9.8%) and the lowest at 13.5 m of distance (6.5%). The site of pasture, between 7 and 10 m of distance from the tree rows showed the highest benefits of moderate shading on pasture traits.

Resposta do tifton 85 a doses de nitrogênio e intervalos de cortes

This experiment was carried out at Embrapa-Centro Nacional de Pesquisa de Gado de Leite, located in Juiz de Fora, MG, Brazil, from October, 1995 to October, 1997, to evaluate the effects of five N doses (0, 100, 200, 400 and 600 kg/ha/year) and three cutting intervals (two, four and six weeks, during the rainy season, and four, six and eight weeks, during the dry season) on dry matter production and crude protein content of tifton 85. Data were analyzed as randomized blocks design in split-plot, with three replicates. The annual dry matter yield increased up to the highest dose of 600 kg/ha/year of N fertilization and up to four weeks cutting interval, during rainy season, and six-week cutting intervals, during the dry season. The highest production of dry matter was 23.1 ton/ha/year, of which 17.8 ton/ha were obtained in the rainy season. The lowest production was 2.6 ton/ha/year, of which 1.9 ton/ha were obtained in the rainy season. Crude protein content varied inversely with cutting intervals and as the amount of N fertilization increased up to dose of 600 kg/ha/year. The crude protein contents did not differ significantly with cutting intervals during the raining season. The highest level of crude protein obtained was 21.7%. Tifton 85 persistency was hampered in the absence of N fertilization and the shortest cutting interval.

Evaluation under grazing of forage potential of Cynodon grass under two nitrogen and potassium levels

The study was undertaken in Coronel Pacheco - MG (National Dairy Cattle Reserch Center of the Brazilian Agricultural Corporation - EMBRAPA), to evaluate, under grazing conditions, the Cynodon nlenfuensis, Vanderyst and three cultivars of Cynodon dactylon, L. Pers. (Florona, Florakirk, Florico), fertilized with either 250:200 or 500:400 kg/ha/year of N:K2O. The experimental design was a randomized blocks, in split-plot, and three replications. No significant difference on dry matter yield between the two rates of N/K2O were found. In both N:K2O rates, Florakirk cultivar presented the highest annual dry matter yield, however, in the dry season it showed a low yield level. The Florico was the cultivar with the lowest dry matter yield. The best and the worst forage distribution were exhibited by cultivars Florona and Florakirk, respectively. The CP contents in the forage was not influenced by either nitrogen rates or season, and directly related to the leaf-stem ratio. The highest CP contents were found in Florakirk, while the lowest in african stargrass grass and Florico cultivar. The IVDMD of forage produced during the rainy season was slightly superior to those of the dry season. The N:K2O rates did not influence IVDMD, which were higher in Florakirk and Florona cultivars.The study was undertaken in Coronel Pacheco – MG (National Dairy Cattle Reserch Center of the Brazilian Agricultural Corporation – EMBRAPA), to evaluate, under grazing conditions, the Cynodon nlenfuensis, Vanderyst and three cultivars of Cynodon dactylon, L. Pers. (Florona, Florakirk, Florico), fertilized with either 250:200 or 500:400 kg/ha/year of N:K2O. The experimental design was a randomized blocks, in split-plot, and three replications. No significant difference on dry matter yield between the two rates of N/K2O were found. In both N:K2O rates, Florakirk cultivar presented the highest annual dry matter yield, however, in the dry season it showed a low yield level. The Florico was the cultivar with the lowest dry matter yield. The best and the worst forage distribution were exhibited by cultivars Florona and Florakirk, respectively. The CP contents in the forage was not influenced by either nitrogen rates or season, and directly related to the leaf-stem ratio. The highest CP contents were found in Florakirk, while the lowest in african stargrass grass and Florico cultivar. The IVDMD of forage produced during the rainy season was slightly superior to those of the dry season. The N:K2O rates did not influence IVDMD, which were higher in Florakirk and Florona cultivars.

Cultivares de alfafa em área de influência da Mata Atlântica no Estado de Minas Gerais

Este trabalho teve como objetivo avaliar o potencial forrageiro de cultivares de alfafa ( Medicago sativa L.) em area de influencia da Mata Atlântica no Estado de Minas Gerais. Foram avaliadas 30 cultivares de alfafa em delineamento de blocos ao acaso com tres repeticoes. As sementes foram infectadas com a estirpe de Rhizobium melilotii BR 7407. No periodo das chuvas e da seca houve diferencas significativas entre as cultivares quanto ao potencial de producao de forragem, relacao folha/caule e tolerância a pragas e doencas. Quanto ao teor de proteina bruta, houve diferencas significativas entre as cultivares, somente no periodo das chuvas. As cultivares que se destacaram na maioria dos parâmetros avaliados foram a Crioula, P30, Monarca e Florida 77. As maiores producoes de forragem nas estacoes das chuvas e da seca foram obtidas pela cultivar Crioula, constituindo, assim, boa opcao para o cultivo da alfafa na Zona da Mata de Minas Gerais.

Dinâmica da serapilheira em pastagens de braquiária em sistema silvipastoril e monocultura

O objetivo deste trabalho foi avaliar o efeito da introducao de leguminosas arboreas e eucalipto em pastagens de braquiaria (Urochloa decumbens cv. Basilisk), na dinâmica da serapilheira. O estudo foi realizado em sistema silvipastoril e em monocultura, em 12 meses. O delineamento experimental foi o de blocos ao acaso, com seis repeticoes e cinco animais por piquete. Foram avaliadas a serapilheira existente e a depositada. A serapilheira existente teve media anual de 5.038 e 3.944 kg ha-1, no sistema silvipastoril e na monocultura, respectivamente. O sistema silvipastoril causou um acrescimo significativo na serapilheira depositada. A quantidade de nitrogenio da serapilheira depositada foi maior no sistema silvipastoril, do que na monocultura, respectivamente, 228 kg ha-1 por ano e 107 kg ha-1 por ano. A presenca de leguminosas e de eucalipto em sistema silvipastoril proporcionou aumentos nas quantidades de nitrogenio, comprovados pela analise isotopica de 13C, e materia seca de serapilheira. Incrementos na producao de serapilheira rica em nitrogenio pode contribuir para a sustentabilidade das pastagens de braquiaria a longo prazo.

Efeito do manejo pós-plantio no estabelecimento de pastagem de capim-elefante

A good establishment is an important condition to obtain adequate levels of productivity in elephantgrass pastures. However, besides the adoption of good agronomic practices at planting, it is necessary to assure that the post-planting management is correct, to favor the future productivity and persistence of the pasture. Aiming at obtaining a good initial density of elephant-grass in the pastures, various post-planting management systems were studied. The following treatments were compared: grazing three months after planting, followed by cutting at 20 cm height from ground level (P20-3), at 40 cm (P40-3) and at 80 cm (P80-3); cutting three months after planting, at 20 cm from ground level (C20-3) and cutting four months after planting at 20 cm from ground level (C20-4). The experiment was undertaken in Coronel Pacheco, MG, in a red-yellow latosol. Experimental design was randomized blocks with four replications, and plots measured 8 x 10 meters. Forage availability, number of plants per hectare and percentage soil cover did not differ among treatments. The cutting at 20 cm height from ground level, three months after planting did not contribute to increase plant density or forage dry matter yield. Basal tillering was not affected by treatments. It was concluded that elephant-grass pastures can be grazed three months after planting, without reducing its productivity thereafter.

Avaliação de cultivares de alfafa na Zona da Mata de Minas Gerais

O presente trabalho foi conduzido na Embrapa-Centro Nacional de Pesquisa de Gado de Leite, Coronel Pacheco, MG. O objetivo do trabalho foi avaliar o potencial forrageiro de cultivares de alfafa na regiao da Zona da Mata de Minas Gerais. Foram avaliadas quatorze cultivares de alfafa em delineamento experimental de blocos ao acaso com tres repeticoes. A densidade de semeadura foi de 15 kg/ha de sementes puras viaveis, com o plantio sendo realizado em sulcos, com espacos, entre si, de 20 cm. As sementes foram infectadas com estirpes de Rhizobium melilotii . As adubacoes para estabelecimento e manutencao foram recomendadas conforme a analise do solo e na exigencia nutricional da alfafa. Observaram-se diferencas significativas entre as cultivares quanto ao potencial para producao de forragem, teor de proteina bruta, relacao caule/folha e tolerância a pragas e doencas. As cultivares Crioula e Cibola situaram-se no grupo das mais promissoras, constituindo, assim, boa opcao para o cultivo da alfafa na Zona da Mata de Minas Gerais.