RESUMO
Because legumes are a very important feed source for ruminants, the aim of this study was to evaluate the ideal inclusion level of hay Arachis pintoi cv. Belmonte in sheep diets by measuring the dry matter intake (DMI), concentration of volatile fatty acids, ammonia-nitrogen concentration, ruminal pH and the in situ degradability of dry matter (DM) and crude protein (CP). In the experiment with four sheep, a 4 × 4 Latin Square design was used with four periods and four treatments (0%, 30%, 60% and 100% Arachis replacing grass hay). Significant interactions were observed between treatments and sampling times for ammonia-nitrogen and acetate, propionate and butyrate concentration and the acetate:propionate ratio. The ruminal pH and total volatile fatty acids concentration were not affected by interaction between treatments and sampling time. The degradation of DM and CP was similar, rising with the increasing content of Arachis, showing a linear effect. The treatment containing 60% of Arachis showed best results, with good levels of daily weight gain and higher ruminal concentrations of volatile fatty acids. The legume showed high levels of CP, high digestibility and appropriate levels of fibre, with excellent standards of degradation and ruminal characteristics. The use of the legume Arachis for ruminants is a promising option of nutrient supply to meet production demands of these animals.
Assuntos
Ração Animal/análise , Arachis/química , Dieta/veterinária , Digestão/fisiologia , Ovinos/fisiologia , Amônia/química , Fenômenos Fisiológicos da Nutrição Animal , Animais , Concentração de Íons de Hidrogênio , Masculino , Nitrogênio/química , Nitrogênio/metabolismo , Rúmen/química , Rúmen/fisiologiaRESUMO
Studies on animal nutrition have shown factors that affect livestock yield and their interaction with the environment, through assessments on food nutritional values, nutrient metabolism in livestock and biochemical parameters related to nutrition and animal breeding. Inclusion levels of hay Arachis pintoi cv. Belmonte in the diet of sheep were studied by measuring the dry matter intake (DMI), production of short chain fatty acids (SCFA), ammonia nitrogen (NH3-N) and rumen pH. Four males Santa Inês sheep with cannulas in the rumen were used in a 4x4 Latin Square design with four periods (21 days each) and four treatments that corresponded to the inclusion levels (0%, 30%, 60% and 100%) of Arachis pintoi cv. Belmonte to replace grass hay Cynodon dactylon cv. Coastcross in the diet. The DMI showed a quadratic effect increased until treatment with 60% of Arachis and reduced in the treatment with 100% of the legume. Significant interaction was observed between treatments and sampling times for NH3-N and acetate, propionate and butyrate concentration and the acetate:propionate ratio. There was no interaction between treatments and sampling time for rumen pH and total VFA concentration. It is observed a rapid increase in ammonia concentration until 2 hours after the feeding, and then a decline is seen. At 8 hours after the feeding, the quadratic effect occurred (P0.05) increasing NH
O artigo não apresenta resumo em português.
RESUMO
The use of the associacion of grasses and legumes results in a good forage yield as well as a good animal performance due to maintenance of adequate levels of crude protein (CP) in the animal diet, both the direct effect of the ingestion of legumes, or even through indirect effect of the introduction of nitrogen by legumes in the pasture, thereby increasing the production of forage mass. However, the seeds of legumines have the so-called hardness seeds or dormant according to their coats impermeable to water. The hardness of the seed prevents the germination of the same since these seeds have a hard shell impervious to water and gas exchange, not allowing the imbibition of water by the seed, or embryo oxygenation. This dormancy may be broken by various known methods such as scarification, promoting cracks in the seed coat allowing the entry of water therein. In the case of Macrotyloma axillare exposure of seeds to scarification method has proven to be an efficient way to break dormancy and promoting seed germination. The aim of the present work was to evaluate the viability of seeds after suffering dormancy by immersion seeds in sulfuric acid. The experiment to break dormancy Macrotyloma axillares cv. Guatá was conducted in the laboratory of Plant Physiology at the Intituto de Zootecnia in Nova Odessa, São Paulo State, using the seeds that were stored in a cold room with temper
ês.
RESUMO
The productivity of forage grasses is due to continuous emission of leaves and tillers, ensuring the restoration of leaf área after cutting or grazing, thus ensuring the sustainability of forage. This study aimed to asses the total number tillers in different acessions of Panicum maximum Jacq. The experiment was carried in field belonging to the Instituto de Zootecnia located in Nova Odessa / SP. Evaluated two new accesses Panicum maximum, and two commercial cultivars. The cultivars tested were Aruana, Milenio, NO 2487, NO 78, and the two latter belonging to the Germoplasm Collection of the IZ. The experimental desing was in randomized complete block with four replications. The experimental area consisted of 16 plots of 10 m2 (5 x 2 m) each. The experimental area was analyzed and according to the results, received dolomitic limestone corresponding 2t /ha, two months before the implementation of the experiment. Sowing was made by broad costing together with 80 kg/ha of P2O5 in the form of single superphosfate. After 60 days of implantation of the experiment it was a made a leveling of the plots to a height of about 15 cm. After this it was applied 250g of the 20-00-20 fertilizer/plot. Thirty days after the standardization it was evaluated the total number of tillers of the cultivars, using a metal frame of 0.5 x 0.5m which was thrown at random on each of the 16 plots, leaving on
ês.
RESUMO
The productivity of forage grasses is due to continuous emission of leaves and tillers, ensuring the restoration of leaf área after cutting or grazing, thus ensuring the sustainability of forage. This study aimed to asses the total number tillers in different acessions of Panicum maximum Jacq. The experiment was carried in field belonging to the Instituto de Zootecnia located in Nova Odessa / SP. Evaluated two new accesses Panicum maximum, and two commercial cultivars. The cultivars tested were Aruana, Milenio, NO 2487, NO 78, and the two latter belonging to the Germoplasm Collection of the IZ. The experimental desing was in randomized complete block with four replications. The experimental area consisted of 16 plots of 10 m2 (5 x 2 m) each. The experimental area was analyzed and according to the results, received dolomitic limestone corresponding 2t /ha, two months before the implementation of the experiment. Sowing was made by broad costing together with 80 kg/ha of P2O5 in the form of single superphosfate. After 60 days of implantation of the experiment it was a made a leveling of the plots to a height of about 15 cm. After this it was applied 250g of the 20-00-20 fertilizer/plot. Thirty days after the standardization it was evaluated the total number of tillers of the cultivars, using a metal frame of 0.5 x 0.5m which was thrown at random on each of the 16 plots, leaving on
ês.
RESUMO
The use of the associacion of grasses and legumes results in a good forage yield as well as a good animal performance due to maintenance of adequate levels of crude protein (CP) in the animal diet, both the direct effect of the ingestion of legumes, or even through indirect effect of the introduction of nitrogen by legumes in the pasture, thereby increasing the production of forage mass. However, the seeds of legumines have the so-called hardness seeds or dormant according to their coats impermeable to water. The hardness of the seed prevents the germination of the same since these seeds have a hard shell impervious to water and gas exchange, not allowing the imbibition of water by the seed, or embryo oxygenation. This dormancy may be broken by various known methods such as scarification, promoting cracks in the seed coat allowing the entry of water therein. In the case of Macrotyloma axillare exposure of seeds to scarification method has proven to be an efficient way to break dormancy and promoting seed germination. The aim of the present work was to evaluate the viability of seeds after suffering dormancy by immersion seeds in sulfuric acid. The experiment to break dormancy Macrotyloma axillares cv. Guatá was conducted in the laboratory of Plant Physiology at the Intituto de Zootecnia in Nova Odessa, São Paulo State, using the seeds that were stored in a cold room with temper
ês.
RESUMO
Studies on animal nutrition have shown factors that affect livestock yield and their interaction with the environment, through assessments on food nutritional values, nutrient metabolism in livestock and biochemical parameters related to nutrition and animal breeding. Inclusion levels of hay Arachis pintoi cv. Belmonte in the diet of sheep were studied by measuring the dry matter intake (DMI), production of short chain fatty acids (SCFA), ammonia nitrogen (NH3-N) and rumen pH. Four males Santa Inês sheep with cannulas in the rumen were used in a 4x4 Latin Square design with four periods (21 days each) and four treatments that corresponded to the inclusion levels (0%, 30%, 60% and 100%) of Arachis pintoi cv. Belmonte to replace grass hay Cynodon dactylon cv. Coastcross in the diet. The DMI showed a quadratic effect increased until treatment with 60% of Arachis and reduced in the treatment with 100% of the legume. Significant interaction was observed between treatments and sampling times for NH3-N and acetate, propionate and butyrate concentration and the acetate:propionate ratio. There was no interaction between treatments and sampling time for rumen pH and total VFA concentration. It is observed a rapid increase in ammonia concentration until 2 hours after the feeding, and then a decline is seen. At 8 hours after the feeding, the quadratic effect occurred (P0.05) increasing NH
O artigo não apresenta resumo em português.
RESUMO
The present study was carried out at Instituto de Zootecnia, Nova Odessa - SP. The objective was to evaluate: forage mass and their components, forage accumulation, daily forage accumulation rate, and sward height from two Panicum maximum Jacq. cultivars (Aruana and Tanzania), under two nitrogen rates (150 and 300kg ha-1 de N), and grazed by sheep in rotational stocking with three to seven grazing days and variable resting periods. The variables were evaluated in six, seven and eight grazing cycles in the first, second and third experimental years, respectively. The experimental design was in complete randomized block (four) with two replicates within each block, with grasses as plots (paddocks) and the nitrogen rates as sub-plots, with repeated measures in time. Tanzania grass presented more annual forage accumulation than Aruana grass only in the third experimental year and more daily forage accumulation rate in the second and third years. It showed greater height and forage mass left after grazing than Aruana grass because it presents thicker and stiffer stems that makes difficult the sward lowering by animals. The rate of 300kg of N/ha/year presented greater values than the one of 150kg in the total forage accumulation rate. But when it is considered the ratio: quilogram of forage mass produced per quilogram of nitrogen applied it was less efficient than the one of 150kg.
O presente estudo foi conduzido no Instituto de Zootecnia de Nova Odessa - SP. Teve por objetivos avaliar: massa de forragem e seus componentes, acúmulo de forragem, taxa diária de acúmulo de forragem e altura do dossel de duas cultivares de Panicum maximum (Aruana e Tanzânia) submetidas a doses de nitrogênio (150 e 300kg ha-1 de N) e pastejadas por ovinos em sistema de lotação rotacionada, com três a sete dias de pastejo e período de descanso variável. As variáveis foram avaliadas em seis, sete e oito ciclos de pastejo no primeiro, segundo e terceiro anos experimentais, respectivamente. O delineamento experimental foi de blocos completos casualizados (quatro), com duas repetições dentro do bloco, em esquema de parcelas subdivididas, sendo o fator cultivar as parcelas e doses de N as subparcelas, com medidas repetidas no tempo. O Tanzânia apresentou maior acúmulo de forragem em relação ao Aruana somente no terceiro ano e maior taxa diária de acúmulo de forragem no segundo e terceiro ano. Apresentou maiores altura e massa de forragem pós-pastejo que o Aruana, por apresentar colmos mais grossos e rijos que dificultaram o rebaixamento do relvado pelos animais. A dose de 300kg de N/ha/ ano proporcionou maior acúmulo e taxa diária de acúmulo de forragem que a dose de 150kg de N/ha/ano. Entretanto, a eficiência de utilização do N foi maior na menor dose.
RESUMO
The present study was carried out at Instituto de Zootecnia, Nova Odessa - SP. The objective was to evaluate: forage mass and their components, forage accumulation, daily forage accumulation rate, and sward height from two Panicum maximum Jacq. cultivars (Aruana and Tanzania), under two nitrogen rates (150 and 300kg ha-1 de N), and grazed by sheep in rotational stocking with three to seven grazing days and variable resting periods. The variables were evaluated in six, seven and eight grazing cycles in the first, second and third experimental years, respectively. The experimental design was in complete randomized block (four) with two replicates within each block, with grasses as plots (paddocks) and the nitrogen rates as sub-plots, with repeated measures in time. Tanzania grass presented more annual forage accumulation than Aruana grass only in the third experimental year and more daily forage accumulation rate in the second and third years. It showed greater height and forage mass left after grazing than Aruana grass because it presents thicker and stiffer stems that makes difficult the sward lowering by animals. The rate of 300kg of N/ha/year presented greater values than the one of 150kg in the total forage accumulation rate. But when it is considered the ratio: quilogram of forage mass produced per quilogram of nitrogen applied it was less efficient than the one of 150kg.
O presente estudo foi conduzido no Instituto de Zootecnia de Nova Odessa - SP. Teve por objetivos avaliar: massa de forragem e seus componentes, acúmulo de forragem, taxa diária de acúmulo de forragem e altura do dossel de duas cultivares de Panicum maximum (Aruana e Tanzânia) submetidas a doses de nitrogênio (150 e 300kg ha-1 de N) e pastejadas por ovinos em sistema de lotação rotacionada, com três a sete dias de pastejo e período de descanso variável. As variáveis foram avaliadas em seis, sete e oito ciclos de pastejo no primeiro, segundo e terceiro anos experimentais, respectivamente. O delineamento experimental foi de blocos completos casualizados (quatro), com duas repetições dentro do bloco, em esquema de parcelas subdivididas, sendo o fator cultivar as parcelas e doses de N as subparcelas, com medidas repetidas no tempo. O Tanzânia apresentou maior acúmulo de forragem em relação ao Aruana somente no terceiro ano e maior taxa diária de acúmulo de forragem no segundo e terceiro ano. Apresentou maiores altura e massa de forragem pós-pastejo que o Aruana, por apresentar colmos mais grossos e rijos que dificultaram o rebaixamento do relvado pelos animais. A dose de 300kg de N/ha/ ano proporcionou maior acúmulo e taxa diária de acúmulo de forragem que a dose de 150kg de N/ha/ano. Entretanto, a eficiência de utilização do N foi maior na menor dose.
RESUMO
The experiment was carried out at Brotas Experimental Station, SP in a soil classified as Quartzpsamment, with the objectives of evaluating the effect of nitrogen rates applied at the end of the raining season (March) upon the dry matter yield, the seasonal forage production along the year; the nitrogen concentration in the forage and; the nitrogen extraction by Guaçugrass (Pennisetum purpureum Schum. cv. Guaçu), during two years (March/1998 to March/ 2000). The experimental design was a complete Randomized Block, with four nitrogen rates (60, 120, 180 and 240 kg ha-1) and 12 replications. The plots measured 6,0 x 4,8m with a cutting area of 9,6 m2. The cuts were effected in the months of May, September, November, January and March of each experimental year. The application of the nitrogen rates at the end of the raining season (March), besides increasing the yearly total forage yield, increased the forage yield during the dry winter period, improving the distribution of the forage production along the year. As an average of the four nitrogen rates, 49% and 37% of the annual yield was produced during the dry period in the first and second experimental year, respectively. The nitrogen extraction by the grass increased in decreasing proportions as the nitrogen rates raised. The herbage nitrogen concentrations raised linearly with the nitrogen rates in the first two cuttings after
O experimento foi conduzido em área da Estação Experimental de Brotas, SP em solo classificado como Neossolo Quartzarênico, com o objetivo de avaliar doses de nitrogênio aplicadas em março, na produção de massa seca, na distribuição estacional da forragem produzida ao longo do ano, na concentração de nitrogênio e na extração de nitrogênio pelo capim-elefante (Pennisetum purpureum Schum) cv. Guaçu, no período de 7 de março de 1998 a 7 de março de 2000. O delineamento experimental foi o de blocos ao acaso, com quatro doses de nitrogênio (60, 120, 180 e 240 kg ha-1), e doze repetições. Cortes manuais no capim-Guaçu foram efetuados em maio, setembro, novembro, janeiro e março de cada ano experimental. As aplicações das doses de nitrog ênio em março, além de aumentarem as produções de forragem no período crítico e no total anual, melhoraram a distribuição de forragem ao longo do ano. Como média das doses de nitrog ênio, 49% e 37% da forragem foi produzida no período considerado das secas e 67% e 47% no período das secas mais o do início da primavera, respectivamente para o primeiro e segundo ano experimental. A extração de nitrogênio pelo capim-Guaçu aumentou em proporções decrescentes com o incremento das doses de nitrogênio. As concentrações de N na forragem aumentaram linearmente nos dois primeiros cortes dos dois anos e no terceiro corte do segundo ano, com as doses de nitrogêni
RESUMO
Pastures degradation is one of the main hindrances of the brazilian cattle breeding, at the present time. Thus, the objective of this work was to assess the contents of nonstructural carbohydrates, total nitrogen and dry matter yield of roots of Brachiaria decumbens Stapf. growing in a soil from a degraded pasture in relation to sulphur, nitrogen and lime rates. The experiment was carried out in greenhouse during the summer. The experimental treatments steined from a 4x4x3 factorial combination of rates of lime, nitrogen and sulphur, respectively. Nitrogen rates were 0, 180, 630 and 1080 mg dm-3; lime rates were 0, 1.587,6, 3.175,2 and 4.762,8 mg dm-3, whereas sulphur rates were 0, 108 and 216 mg dm-3. The experimental design was a completely randomized design, with three replications. It was observed effect (P 0.05) for the nitrogen rates in all evaluated variables. The behavior was linear and decreasing for the nonstrucutural carbohydrates and quadratic for the total nitrogen concentration and dry matter in the roots of the grass. The sulphur influenced (P 0.05) just the nonstructural carbohydrates concentration that had decreasing linear behavior.
A degradação das pastagens constitui-se em um dos principais entraves da pecuária brasileira, na atualidade. Diante disso, o objetivo deste trabalho foi determinar os teores de carboidratos não estruturais, nitrogênio total e produção de massa seca das raízes do capimbraquiária, cultivado em solo proveniente de uma pastagem degradada e submetida a doses de enxofre, nitrogênio e calcário. O experimento foi conduzido em casa-de-vegetação durante o período de verão. Empregou-se um esquema fatorial 4x4x3, perfazendo 48 combinações, as quais foram distribuídas no delineamento experimental de blocos completos ao acaso, com três repetições. Foram utilizadas quatro doses de nitrogênio (0, 180, 630 e 1.080 mg dm-3), quatro doses de calcário (0, 1.587,6, 3.175,2 e 4.762,8 mg dm-3) e três doses de enxofre (0, 108 e 216 mg dm-3). Observou-se efeito (P 0,05) para as doses de nitrogênio sobre as variáveis analisadas. O comportamento foi linear e decrescente para os carboidratos não estruturais e quadrático para a concentração de nitrogênio total e produção de massa seca de raiz. O enxofre influenciou (P 0,05) apenas os teores de carboidratos não estruturais que, teve comportamento linear e decrescente.
RESUMO
Pastures degradation is one of the main hindrances of the brazilian cattle breeding, at the present time. Thus, the objective of this work was to assess the contents of nonstructural carbohydrates, total nitrogen and dry matter yield of roots of Brachiaria decumbens Stapf. growing in a soil from a degraded pasture in relation to sulphur, nitrogen and lime rates. The experiment was carried out in greenhouse during the summer. The experimental treatments steined from a 4x4x3 factorial combination of rates of lime, nitrogen and sulphur, respectively. Nitrogen rates were 0, 180, 630 and 1080 mg dm-3; lime rates were 0, 1.587,6, 3.175,2 and 4.762,8 mg dm-3, whereas sulphur rates were 0, 108 and 216 mg dm-3. The experimental design was a completely randomized design, with three replications. It was observed effect (P 0.05) for the nitrogen rates in all evaluated variables. The behavior was linear and decreasing for the nonstrucutural carbohydrates and quadratic for the total nitrogen concentration and dry matter in the roots of the grass. The sulphur influenced (P 0.05) just the nonstructural carbohydrates concentration that had decreasing linear behavior.
A degradação das pastagens constitui-se em um dos principais entraves da pecuária brasileira, na atualidade. Diante disso, o objetivo deste trabalho foi determinar os teores de carboidratos não estruturais, nitrogênio total e produção de massa seca das raízes do capimbraquiária, cultivado em solo proveniente de uma pastagem degradada e submetida a doses de enxofre, nitrogênio e calcário. O experimento foi conduzido em casa-de-vegetação durante o período de verão. Empregou-se um esquema fatorial 4x4x3, perfazendo 48 combinações, as quais foram distribuídas no delineamento experimental de blocos completos ao acaso, com três repetições. Foram utilizadas quatro doses de nitrogênio (0, 180, 630 e 1.080 mg dm-3), quatro doses de calcário (0, 1.587,6, 3.175,2 e 4.762,8 mg dm-3) e três doses de enxofre (0, 108 e 216 mg dm-3). Observou-se efeito (P 0,05) para as doses de nitrogênio sobre as variáveis analisadas. O comportamento foi linear e decrescente para os carboidratos não estruturais e quadrático para a concentração de nitrogênio total e produção de massa seca de raiz. O enxofre influenciou (P 0,05) apenas os teores de carboidratos não estruturais que, teve comportamento linear e decrescente.
RESUMO
The experiment was carried out at Brotas Experimental Station, SP in a soil classified as Quartzpsamment, with the objectives of evaluating the effect of nitrogen rates applied at the end of the raining season (March) upon the dry matter yield, the seasonal forage production along the year; the nitrogen concentration in the forage and; the nitrogen extraction by Guaçugrass (Pennisetum purpureum Schum. cv. Guaçu), during two years (March/1998 to March/ 2000). The experimental design was a complete Randomized Block, with four nitrogen rates (60, 120, 180 and 240 kg ha-1) and 12 replications. The plots measured 6,0 x 4,8m with a cutting area of 9,6 m2. The cuts were effected in the months of May, September, November, January and March of each experimental year. The application of the nitrogen rates at the end of the raining season (March), besides increasing the yearly total forage yield, increased the forage yield during the dry winter period, improving the distribution of the forage production along the year. As an average of the four nitrogen rates, 49% and 37% of the annual yield was produced during the dry period in the first and second experimental year, respectively. The nitrogen extraction by the grass increased in decreasing proportions as the nitrogen rates raised. The herbage nitrogen concentrations raised linearly with the nitrogen rates in the first two cuttings after
O experimento foi conduzido em área da Estação Experimental de Brotas, SP em solo classificado como Neossolo Quartzarênico, com o objetivo de avaliar doses de nitrogênio aplicadas em março, na produção de massa seca, na distribuição estacional da forragem produzida ao longo do ano, na concentração de nitrogênio e na extração de nitrogênio pelo capim-elefante (Pennisetum purpureum Schum) cv. Guaçu, no período de 7 de março de 1998 a 7 de março de 2000. O delineamento experimental foi o de blocos ao acaso, com quatro doses de nitrogênio (60, 120, 180 e 240 kg ha-1), e doze repetições. Cortes manuais no capim-Guaçu foram efetuados em maio, setembro, novembro, janeiro e março de cada ano experimental. As aplicações das doses de nitrog ênio em março, além de aumentarem as produções de forragem no período crítico e no total anual, melhoraram a distribuição de forragem ao longo do ano. Como média das doses de nitrog ênio, 49% e 37% da forragem foi produzida no período considerado das secas e 67% e 47% no período das secas mais o do início da primavera, respectivamente para o primeiro e segundo ano experimental. A extração de nitrogênio pelo capim-Guaçu aumentou em proporções decrescentes com o incremento das doses de nitrogênio. As concentrações de N na forragem aumentaram linearmente nos dois primeiros cortes dos dois anos e no terceiro corte do segundo ano, com as doses de nitrogêni
RESUMO
Alfalfa cultivar Crioula (Medicago sativa cv. Crioula) is grown in South Brazil and only a few studies on the plants' boron requirement are available. A greenhouse experiment was carried out with alfalfa to measure boron acquisition, production and distribution in the plant; data on critical level and production potentials were recorded. Plants were grown in ground quartz added with 1 L of solution, with the following boron rates: 0, 0.0625, 0.125, 0.25, 0.50, 1.00, and 2.00 mg L-1. Plants were harvested at 46 days of growth. Forage dry mass was increased by boron supply and dry matter accumulation was considerably low in control. Boron concentration in the leaves was higher than in the stems or roots. Boron utilization from the external solution reached 90% at 0.0625 mg L-1 and sharply decreased with further increasing boron rates. Boron concentration and content in the leaves and in plant tops were at maximum when applied boron was between 1.5 and 1.6 mg L-1. Critical levels of boron in plant were 61 mg kg-1 in the leaves and 39 mg kg-1 in plant tops for this cultivar of alfalfa.
O cultivar Crioula de alfafa (Medicago sativa cv. Crioula) é utilizado no Sul do Brasil e existem poucos estudos referentes a sua exigência em boro. Foi conduzido um experimento com alfafa cultivada no inverno, com o objetivo de avaliar a quantidade de boro absorvido pelas plantas, o efeito de doses de boro na produção de massa seca, a distribuição do boro nas plantas e obter informações relacionadas à diagnose de boro nessa forrageira. As doses de 0; 0,0625; 0,125; 0,25; 0,50; 1,00 e 2,00 mg L-1 foram aplicadas no substrato, colocando-se 1 L de solução nutritiva em cada recipiente. As plantas foram cortadas aos 46 dias após o transplante. A massa seca da forrageira foi influenciada pelas doses de boro e foi insignificante quando a solução nutritiva apresentava a mais baixa concentração de boro. A concentração de boro nas folhas foi mais elevada que nas hastes e nas raízes. A utilização de boro da solução atingiu 90% na dose de 0,0625 mg L-1 e decresceu acentuadamente com o incremento das doses de boro. A concentração e o conteúdo de boro nas folhas e na parte aérea da planta foram mais elevados quando o boro se encontrava na solução nutritiva entre 1,5 e 1,6 mg L-1. O nível crítico de boro foi de 61 mg kg-1 nas folhas e 39 mg kg-1 na planta para este cultivar de alfafa.
RESUMO
Alfalfa cultivar Crioula (Medicago sativa cv. Crioula) is grown in South Brazil and only a few studies on the plants' boron requirement are available. A greenhouse experiment was carried out with alfalfa to measure boron acquisition, production and distribution in the plant; data on critical level and production potentials were recorded. Plants were grown in ground quartz added with 1 L of solution, with the following boron rates: 0, 0.0625, 0.125, 0.25, 0.50, 1.00, and 2.00 mg L-1. Plants were harvested at 46 days of growth. Forage dry mass was increased by boron supply and dry matter accumulation was considerably low in control. Boron concentration in the leaves was higher than in the stems or roots. Boron utilization from the external solution reached 90% at 0.0625 mg L-1 and sharply decreased with further increasing boron rates. Boron concentration and content in the leaves and in plant tops were at maximum when applied boron was between 1.5 and 1.6 mg L-1. Critical levels of boron in plant were 61 mg kg-1 in the leaves and 39 mg kg-1 in plant tops for this cultivar of alfalfa.
O cultivar Crioula de alfafa (Medicago sativa cv. Crioula) é utilizado no Sul do Brasil e existem poucos estudos referentes a sua exigência em boro. Foi conduzido um experimento com alfafa cultivada no inverno, com o objetivo de avaliar a quantidade de boro absorvido pelas plantas, o efeito de doses de boro na produção de massa seca, a distribuição do boro nas plantas e obter informações relacionadas à diagnose de boro nessa forrageira. As doses de 0; 0,0625; 0,125; 0,25; 0,50; 1,00 e 2,00 mg L-1 foram aplicadas no substrato, colocando-se 1 L de solução nutritiva em cada recipiente. As plantas foram cortadas aos 46 dias após o transplante. A massa seca da forrageira foi influenciada pelas doses de boro e foi insignificante quando a solução nutritiva apresentava a mais baixa concentração de boro. A concentração de boro nas folhas foi mais elevada que nas hastes e nas raízes. A utilização de boro da solução atingiu 90% na dose de 0,0625 mg L-1 e decresceu acentuadamente com o incremento das doses de boro. A concentração e o conteúdo de boro nas folhas e na parte aérea da planta foram mais elevados quando o boro se encontrava na solução nutritiva entre 1,5 e 1,6 mg L-1. O nível crítico de boro foi de 61 mg kg-1 nas folhas e 39 mg kg-1 na planta para este cultivar de alfafa.
RESUMO
The present work was carried out in a greenhouse with the objective of evaluating the effects of nitrogen and sulfur rates on plant tops dry matter yield, chlorophyll concentration and plant tissue mineral composition in Brachiaria decumbens Stapf. Forty-eight soil cores containing signal grass (tops + roots) were collected in the studied pasture and put in plastic pots. A 4 x 3 factorial (nitrogen rates and sulfur rates) in a randomized complete block design, with four replications, was used. Nitrogen rates were 0; 50; 100 and 200 mg dm-3 where as sulfur rates were 0; 30 and 60 mg dm-3. Plants were harvested three times at: 40 days after the plots uniformization, 40 days after the first harvest and 40 days after the second harvest. The results showed that the nitrogen x sulfur interaction was significant (P 0.01) for the plant tops forage yield in the first and second harvests. Nitrogen rates significantly (P 0.01) influenced nitrogen concentration in the newly expanded leaf laminae from the first and third harvests. Nitrogen x sulfur interaction was significant (P 0.01) for the nitrogen concentration in diagnostic leaf laminae in the second harvest.
O presente trabalho foi desenvolvido, em casa de vegetação, com o objetivo de avaliar o efeito da aplicação de nitrogênio e enxofre na produção de massa seca da parte aérea, na concentração de nitrogênio e de enxofre nas lâminas de folhas recém-expandidas e no valor SPAD da Brachiaria decumbens Stapf. Utilizaram-se 48 cilindros contendo solo e capim Braquiária (parte aérea + raízes) coletados em pastagem formada há mais de 10 anos e colocados em vasos plásticos. Empregou-se um esquema fatorial 4 x 3 (doses de nitrogênio e de enxofre) perfazendo 12 combinações, as quais foram distribuídas segundo o delineamento experimental de blocos completos ao acaso, com quatro repetições. Foram utilizadas quatro doses de nitrogênio (0; 50; 100 e 200 mg dm-3) em combinação com três doses de enxofre (0; 30 e 60 mg dm-3). O primeiro corte das plantas ocorreu 40 dias após o corte de uniformização, o segundo corte aos 40 dias após o primeiro corte e o terceiro corte aos 40 dias após o segundo corte. Os resultados evidenciaram que a interação entre nitrogênio e enxofre foi significativa (P 0,01) para a produção de massa seca da parte aérea da Brachiaria decumbens no primeiro e no segundo crescimento. O efeito das doses de nitrogênio na concentração de nitrogênio na folha diagnóstica dessa forrageira resultou em significância (P 0,01) no primeiro e no terceiro crescimento. A interação entre d
RESUMO
The present work was carried out in a greenhouse with the objective of evaluating the effects of nitrogen and sulfur rates on plant tops dry matter yield, chlorophyll concentration and plant tissue mineral composition in Brachiaria decumbens Stapf. Forty-eight soil cores containing signal grass (tops + roots) were collected in the studied pasture and put in plastic pots. A 4 x 3 factorial (nitrogen rates and sulfur rates) in a randomized complete block design, with four replications, was used. Nitrogen rates were 0; 50; 100 and 200 mg dm-3 where as sulfur rates were 0; 30 and 60 mg dm-3. Plants were harvested three times at: 40 days after the plots uniformization, 40 days after the first harvest and 40 days after the second harvest. The results showed that the nitrogen x sulfur interaction was significant (P 0.01) for the plant tops forage yield in the first and second harvests. Nitrogen rates significantly (P 0.01) influenced nitrogen concentration in the newly expanded leaf laminae from the first and third harvests. Nitrogen x sulfur interaction was significant (P 0.01) for the nitrogen concentration in diagnostic leaf laminae in the second harvest.
O presente trabalho foi desenvolvido, em casa de vegetação, com o objetivo de avaliar o efeito da aplicação de nitrogênio e enxofre na produção de massa seca da parte aérea, na concentração de nitrogênio e de enxofre nas lâminas de folhas recém-expandidas e no valor SPAD da Brachiaria decumbens Stapf. Utilizaram-se 48 cilindros contendo solo e capim Braquiária (parte aérea + raízes) coletados em pastagem formada há mais de 10 anos e colocados em vasos plásticos. Empregou-se um esquema fatorial 4 x 3 (doses de nitrogênio e de enxofre) perfazendo 12 combinações, as quais foram distribuídas segundo o delineamento experimental de blocos completos ao acaso, com quatro repetições. Foram utilizadas quatro doses de nitrogênio (0; 50; 100 e 200 mg dm-3) em combinação com três doses de enxofre (0; 30 e 60 mg dm-3). O primeiro corte das plantas ocorreu 40 dias após o corte de uniformização, o segundo corte aos 40 dias após o primeiro corte e o terceiro corte aos 40 dias após o segundo corte. Os resultados evidenciaram que a interação entre nitrogênio e enxofre foi significativa (P 0,01) para a produção de massa seca da parte aérea da Brachiaria decumbens no primeiro e no segundo crescimento. O efeito das doses de nitrogênio na concentração de nitrogênio na folha diagnóstica dessa forrageira resultou em significância (P 0,01) no primeiro e no terceiro crescimento. A interação entre d