RESUMO

Water magnetization and geoprocessing are increasingly utilized tools in weed management. Our objective was to study the influence of water magnetization on herbicide efficiency and to verify whether there is a relationship between control scores and the normalized difference vegetation index (NDVI). In the laboratory experiment, water was subjected to magnetization and evaluated with respect to four characteristics. In the field experiment, plots of Brachiaria grass were subjected to treatments in a factorial scheme (6 × 2 + 1). Six herbicidal factors (doses of glyphosate and glyphosate + 2,4-D) and the magnetization or absence of magnetization of the spray solution were evaluated and compared against the control treatment (without spraying). Weed control assessments were carried out six times. Images were obtained using an embedded multispectral camera to determine the NDVI values. Data related to water characteristics were analyzed using the t test. Weed control and NDVI data were subjected to analysis of variance and are presented in regression graphs. Dispersion analysis of NDVI data was performed according to the control scores. The magnetization process decreased the pH of the water and increased the surface tension, but it did not influence the control scores or the NDVI. As the glyphosate dose was increased, the control scores were higher and the NDVI values were lower. Magnetized water did not affect the biological efficiency of the herbicides, and there was a strong correlation between the control scores and the NDVI values.

A magnetização da água e o geoprocessamento são ferramentas cada vez mais utilizadas no manejo de ervas daninhas. Nosso objetivo foi estudar a influência da magnetização da água na eficiência do herbicida e verificar se existe uma relação entre os escores de controle e o índice de vegetação por diferença normalizada (NDVI). No experimento de laboratório, a água foi submetida à magnetização e avaliada em relação a quatro características. No experimento de campo, parcelas de capim-braquiária foram submetidas a tratamentos em esquema fatorial (6 × 2 + 1). Seis fatores herbicidas (doses de glyphosate e glyphosate + 2,4-D) e a magnetização ou ausência de magnetização da calda foram avaliados e comparados com o tratamento controle (sem pulverização). Avaliações de controle de plantas daninhas foram realizadas seis vezes. As imagens foram obtidas usando uma câmera multiespectral incorporada para determinar os valores de NDVI. Os dados relacionados às características da água foram analisados por meio do teste t. O controle de plantas daninhas e os dados de NDVI foram submetidos à análise de variância e são apresentados em gráficos de regressão. A análise de dispersão dos dados NDVI foi realizada de acordo com os escores de controle. O processo de magnetização diminuiu o pH da água e aumentou a tensão superficial, mas não influenciou nos escores de controle ou no NDVI. Conforme a dose de glyphosate foi aumentada, os escores de controle foram maiores e os valores de NDVI foram menores. A água magnetizada não afetou a eficiência biológica dos herbicidas, e houve uma forte correlação entre os escores de controle e os valores de NDVI.

Assuntos

RESUMO

Water magnetization and geoprocessing are increasingly utilized tools in weed management. Our objective was to study the influence of water magnetization on herbicide efficiency and to verify whether there is a relationship between control scores and the normalized difference vegetation index (NDVI). In the laboratory experiment, water was subjected to magnetization and evaluated with respect to four characteristics. In the field experiment, plots of Brachiaria grass were subjected to treatments in a factorial scheme (6 × 2 + 1). Six herbicidal factors (doses of glyphosate and glyphosate + 2,4-D) and the magnetization or absence of magnetization of the spray solution were evaluated and compared against the control treatment (without spraying). Weed control assessments were carried out six times. Images were obtained using an embedded multispectral camera to determine the NDVI values. Data related to water characteristics were analyzed using the t test. Weed control and NDVI data were subjected to analysis of variance and are presented in regression graphs. Dispersion analysis of NDVI data was performed according to the control scores. The magnetization process decreased the pH of the water and increased the surface tension, but it did not influence the control scores or the NDVI. As the glyphosate dose was increased, the control scores were higher and the NDVI values were lower. Magnetized water did not affect the biological efficiency of the herbicides, and there was a strong correlation between the control scores and the NDVI values.(AU)

A magnetização da água e o geoprocessamento são ferramentas cada vez mais utilizadas no manejo de ervas daninhas. Nosso objetivo foi estudar a influência da magnetização da água na eficiência do herbicida e verificar se existe uma relação entre os escores de controle e o índice de vegetação por diferença normalizada (NDVI). No experimento de laboratório, a água foi submetida à magnetização e avaliada em relação a quatro características. No experimento de campo, parcelas de capim-braquiária foram submetidas a tratamentos em esquema fatorial (6 × 2 + 1). Seis fatores herbicidas (doses de glyphosate e glyphosate + 2,4-D) e a magnetização ou ausência de magnetização da calda foram avaliados e comparados com o tratamento controle (sem pulverização). Avaliações de controle de plantas daninhas foram realizadas seis vezes. As imagens foram obtidas usando uma câmera multiespectral incorporada para determinar os valores de NDVI. Os dados relacionados às características da água foram analisados por meio do teste t. O controle de plantas daninhas e os dados de NDVI foram submetidos à análise de variância e são apresentados em gráficos de regressão. A análise de dispersão dos dados NDVI foi realizada de acordo com os escores de controle. O processo de magnetização diminuiu o pH da água e aumentou a tensão superficial, mas não influenciou nos escores de controle ou no NDVI. Conforme a dose de glyphosate foi aumentada, os escores de controle foram maiores e os valores de NDVI foram menores. A água magnetizada não afetou a eficiência biológica dos herbicidas, e houve uma forte correlação entre os escores de controle e os valores de NDVI.(AU)

Assuntos

RESUMO

Zinc (Zn) is an essential micronutrient for plant growth, and Zn deficiency is a global issue, especially in tropical soils. This study aimed to investigate the effects of humic acid (HA) and the Zn addition (Zn sulfate + HA) on the growth of maize and brachiaria in two contrasting Oxisols. The potential complexation of Zn sulfate by HA was evaluated by Fourier-transform infrared (FTIR) spectroscopy analysis. Zinc content and its availability in solution and the shoot and root biomass of maize and brachiaria were determined. FTIR spectroscopy revealed the complexation of Zn sulfate by HA through its S and C functional groups. In both Oxisols, solution Zn increased due to the combined use of Zn and HA. In a soil type-dependent manner, maize biomass and Zn in its shoots were affected only by the exclusive use of Zn fertilization. In the Yellow Oxisol, brachiaria growth and Zn accumulated in its shoot were positively affected by the combined use of Zn fertilization with HA. In the Oxisol with lower organic matter content, HA can assure adequate supplying of residual Zn, while increasing growth of brachiaria cultivated in sequence to maize.

Assuntos

RESUMO

Brazil is the largest producer, consumer, and exporter of forage seeds in the world. However, the high incidence of pathogens threatens the seed production system, resulting in decreases in production and quality. Currently, the emphasis has been placed on the use of alternative products as a way of maintaining productivity and environmental sustainability. Thus, the objective of this study was to evaluate the mycoflora associated with the commercial seeds of Brachiaria brizantha and Panicum maximum treated with chemical and alternative fungicide. To test with chemical and alternative treatments, seeds were subjected to fluazinam + thiophanate-methyl, fludioxonil + metalaxyl-M, noni essential oil, rosemary pepper essential oil, sulfuric acid. There was also an untreated control. The most efficient products in the control of incident fungi were, in decreasing order, fluazinam + thiophanate-methyl, fludioxonil + metalaxyl-M, noni essential oil, rosemary pepper essential oil, and sulfuric acid. Fungicides mainly controlled the genera Alternaria, Aspergillus, Bipolaris, Chaetomium, Cladosporium, Colletotrichum, Curvularia, Fusarium, Penicillium, Phoma and Rhizopus. Essential oils showed positive effects in controlling Bipolaris, Curvularia, and Fusarium. Sulfuric acid reduced the incidence of Bipolaris, Colletotrichum, Curvularia, Fusarium, Phoma, and Rhizopus. Seed treatment is one of the promising strategies for obtaining seeds of a healthy quality. As a result, the fungicides and botanical components listed above were promising in reducing fungi associated with forage seeds and can be used for seed treatments and in the development of new products with a natural base through essential oils.

Assuntos

RESUMO

This study aims to evaluate the effects of height (15 and 30 cm) and nitrogen dose (N, 40, 80, and 120 kg ha-1) at the beginning of the stockpiling period on the structural characteristics of the Urochloa brizantha cv. Marandu (Marandu palisade grass) during winter. The falling index of the plant did not vary with the factors under scrutiny (P>0,10). The number of basal tillers was higher (P<0,10) in the 15-cm deferred canopy than in the 30-cm canopy only when the highest N dose was used. Under conditions of application of 0 or 80 kg ha-1 of N, the 30-cm stockpiled canopies showed a higher (P<0,10) forage mass than the 15-cm ones. Associated with reduced canopy height at the beginning of stockpiling period, nitrogen fertilization improves the morphological composition of Marandu palisade grass. To maximize the forage mass in the dry season, the canopies of Marandu palisade grass can be deferred either at 15 cm (fertilized with about 100 kg ha-1 of N) or at 30 cm (with no nitrogen fertilization) at the beginning of the stockpiling period.(AU)

O objetivo deste trabalho foi avaliar os efeitos da altura (15 e 30 cm) e da dose de nitrogênio (N, 0, 40, 80 e 120 kg ha-1) no início do período de diferimento sobre as características estruturais da Urochloa brizantha cv. Marandu (capim-marandu) durante o inverno. O índice de tombamento da planta não variou com os fatores estudados (P>0,10). O número de perfilho basal foi maior (P<10) no dossel diferido com 15 cm do que naquele com 30 cm apenas quando a maior dose de N foi utilizada. Nas condições em que N não foi aplicado e quando 80 kg ha-1 de N foi empregado, os dosséis diferidos com 30 cm apresentaram maior (P<10) massa de forragem do que aqueles com 15 cm. Associada à redução da altura do dossel no início do período de diferimento, a adubação nitrogenada melhora a composição morfológica do capim-marandu. Para maximizar a massa de forragem na época seca do ano, os dosséis de capimmarandu podem, no início do período de diferimento, ser diferidos (i) com 15 cm e adubados com cerca de 100 kg ha-1 de N ou (ii) com 30 cm e sem adubação nitrogenada.(AU)

Assuntos

RESUMO

This study aims to evaluate the effects of height (15 and 30 cm) and nitrogen dose (N, 40, 80, and 120 kg ha-1) at the beginning of the stockpiling period on the structural characteristics of the Urochloa brizantha cv. Marandu (Marandu palisade grass) during winter. The falling index of the plant did not vary with the factors under scrutiny (P>0,10). The number of basal tillers was higher (P<0,10) in the 15-cm deferred canopy than in the 30-cm canopy only when the highest N dose was used. Under conditions of application of 0 or 80 kg ha-1 of N, the 30-cm stockpiled canopies showed a higher (P<0,10) forage mass than the 15-cm ones. Associated with reduced canopy height at the beginning of stockpiling period, nitrogen fertilization improves the morphological composition of Marandu palisade grass. To maximize the forage mass in the dry season, the canopies of Marandu palisade grass can be deferred either at 15 cm (fertilized with about 100 kg ha-1 of N) or at 30 cm (with no nitrogen fertilization) at the beginning of the stockpiling period.

O objetivo deste trabalho foi avaliar os efeitos da altura (15 e 30 cm) e da dose de nitrogênio (N, 0, 40, 80 e 120 kg ha-1) no início do período de diferimento sobre as características estruturais da Urochloa brizantha cv. Marandu (capim-marandu) durante o inverno. O índice de tombamento da planta não variou com os fatores estudados (P>0,10). O número de perfilho basal foi maior (P<10) no dossel diferido com 15 cm do que naquele com 30 cm apenas quando a maior dose de N foi utilizada. Nas condições em que N não foi aplicado e quando 80 kg ha-1 de N foi empregado, os dosséis diferidos com 30 cm apresentaram maior (P<10) massa de forragem do que aqueles com 15 cm. Associada à redução da altura do dossel no início do período de diferimento, a adubação nitrogenada melhora a composição morfológica do capim-marandu. Para maximizar a massa de forragem na época seca do ano, os dosséis de capimmarandu podem, no início do período de diferimento, ser diferidos (i) com 15 cm e adubados com cerca de 100 kg ha-1 de N ou (ii) com 30 cm e sem adubação nitrogenada.

Assuntos

RESUMO

The deferred pasture structure determines the consumption and performance of grazing animals and, in addition, can be influenced by the duration of the deferment period and nitrogen (N) fertilisation. The objective of this work was to evaluate the structural characteristics of Brachiaria brizantha syn. Urochloa brizantha cv. Piatã (piatã palisadegrass) deferred for two periods (79 and 127 days) and with four N doses (0, 40, 80 and 120 kg ha-1) in the Zona da Mata of Minas Gerais, Brazil. The experimental design involved complete randomised blocks and a subdivided plot scheme, with three replications. The 127-day period of deferment resulted in a higher forage mass, falling index, stem percentage and density, but a lower number of tillers, percentage and volumetric density of live leaf blade. The N dose increment, in general, worsened the structural characteristics of the piatã palisadegrass deferred for 127 days. However, with the 79-day period, the N fertilisation increased the volumetric density of live leaf blades and reduced the stem percentage in the forage mass. As a preliminary recommendation, piatã palisadegrass can be deferred for 79 days and fertilised with up to 90 kg ha-1 of N in the region of Zona da Mata de Minas Gerais, Brazil.(AU)

A estrutura do pasto diferido determina o consumo e o desempenho dos animais em pastejo e, ademais, pode ser influenciada pela duração do período de diferimento e pela adubação nitrogenada. O objetivo com este trabalho foi avaliar as características estruturais da Brachiaria brizantha syn. Urochloa brizantha cv. Piatã (capim-piatã) diferida por dois períodos (79 e 127 dias) e com quatro doses de nitrogênio (0, 40, 80 e 120 kg ha-1) na Zona da Mata de Minas Gerais, Brasil. O experimento foi em blocos completos casualizados e em esquema de parcela subdividida, com três repetições. O período de 127 dias de diferimento resultou em maiores massa de forragem, índice de tombamento, porcentagem e densidade volumétrica de colmo, porém em menores número de perfilho, porcentagem e densidade volumétrica de lâmina foliar viva. O incremento da dose de N reduziu a porcentagem de lâmina foliar viva na massa de forragem do capim-piatã diferido por 127 dias. Porém, com o período de 79 dias, a adubação aumentou a densidade volumétrica de lâmina foliar viva e reduziu a porcentagem de colmo na massa de forragem. Como recomendação preliminar, o capim-piatã pode ser diferido por 79 dias e com adubação de até 90 kg ha-1 de N na região da Zona da Mata de Minas Gerais, Brasil.(AU)

Assuntos

RESUMO

In deferred pastures, nitrogen fertilisation and pasture height at the beginning of the deferment period modify the structure and nutritive value of forage. This work was conducted to determine the nitrogen (N) doses and sward heights that were adequate for the deferment of Brachiaria brizantha cv. Marandu syn. Urochloa brizantha cv. Marandu (marandu palisadegrass). Two sward heights (15 and 30 cm) and four N rates (0, 40, 80,120 kg/ha) at the beginning of the deferment period were evaluated in a randomised block design and a factorial scheme with three replications. At the end of the deferment period, the numbers of live and dead tillers, the numbers of tillers with different sizes, the masses of live leaf lamina, dead leaf lamina, live stem and dead stem, the litter mass and the crude protein and neutral detergent fibre contents of the forage were evaluated. With nitrogen fertilisation, there was an increase in the masses of live leaf and live stem in the deferred canopy. With the application of 80 kg/ha of N, the litter mass was higher in the deferred canopy with a height of 30 cm, in relation to that with a height of 15 cm. The highest canopy presented greater stem mass and worse nutritional value when compared to the lowest one. In order to improve forage characteristics, marandu palisadegrass can be deferred by 15 cm and fertilised with 80 kg/ha N. When marandu palisade grass is deferred to 30 cm, nitrogen doses lower than 80 kg/ha can be applied.(AU)

Em pastagens diferidas, a adubação nitrogenada e a altura do pasto no inicio do período de diferimento modificam a estrutura e o valor nutritivo da forragem. Esse trabalho foi conduzido para determinar as doses de nitrogênio (N) e as alturas do dossel mais adequadas para o diferimento da Urochloa brizantha cv. Marandu (capim-marandu). Duas alturas do dossel (15 e 30 cm) e quatro doses de N (0, 40, 80,120 kg/ha) no inicio do período de diferimento foram avaliadas, em delineamento de blocos casualizados e esquema fatorial, com três repetições. Ao final do período de diferimento foram avaliados os números de perfilhos vivos e mortos, os números de perfilhos com diferentes tamanhos, as massas de lâmina foliar viva, lâmina foliar morta, colmo vivo e colmo morto; a massa de serrapilheira e os teores de proteína bruta e fibra em detergente neutro da forragem. Com a adubação nitrogenada, houve incremento das massas de lâmina foliar viva e de colmo vivo nos dosséis diferidos. Com aplicação de 80 kg/ha de N, a massa de serrapilheira foi maior no dossel diferido com 30 cm, em relação àquele com 15 cm. O dossel mais alto apresentou maior massa de colmo e pior valor nutritivo, se comparado ao mais baixo. Para melhorar as características da forragem, o capim-marandu pode ser diferido com 15 cm e adubado com 80 kg/ha de N. Quando o capim-marandu é diferido com 30 cm, doses de nitrogênio inferiores a 80 kg/ha podem ser aplicadas.(AU)

Assuntos

RESUMO

O fósforo é primordial para as pastagens e a adubação combinada com fontes fosfatadas podem aumentar qualidade nutricional e produtiva do Mombaça. Objetivou-se avaliar as características morfológicas, produtivas e nutricionais do capim Mombaça submetido a combinações de fontes de fósforo solúvel e natural. O delineamento experimental foi o inteiramente casualizado, com dez tratamentos e quatro repetições. Os tratamentos consistiram de três fontes e seis combinações de fontes de fosforo equivalente a 90 kg ha-1 de P2O5, sendo: Controle, Rejeito de rocha fosfática (RJ), Superfosfato triplo (ST), Yoorin Master 1 (YR), RJ + ST (70% e 30%), RJ + ST (50% e 50%), RJ + YR (70% e 30%), RJ + YR (50% e 50%), YR + ST (70% e 30%), YR + ST (50% e 50%). O capim Mombaça foi cultivado durante três cortes (60, 105 e 150 DAS).  As combinações YR + ST (50% e 50%), YR + ST (70% e 30%) e RJ + YR (50% e 50%) proporcionaram resultados positivos para caracteres agronômicos e as fontes RJ, RJ + ST (50% e 50%) e RJ + YR (50% e 50%) para teor de P. A adubação fosfatada, independentemente da fonte e mistura, propiciou incremento no capim Mombaça.(AU)

Phosphorus is primordial for pasture and fertilization combined with phosphate sources that can increase the nutritional and productive quality of Mombasa. With that, the objective of this study was to evaluate the morphological, productive and nutritional characteristics of Mombaça grass submitted to combinations of soluble and natural phosphorus sources. The experimental design was randomized with ten treatments and four replications. Controls consist of three sources and six combinations of phosphorus sources equivalent to 90 kg ha-1 of P2O5, namely: Control, Phosphate Rock Tailings (RJ), Triple Superphosphate (ST), Yoorin Master 1 (YR), RJ + ST (70% and 30%), RJ + ST (50% and 50%), RJ + YR (70% and 30%),RJ + YR (50% and 50%), YR + ST (70% and 30) %), YR + ST (50% and 50%). Mombasa grass was grown in three cuts (60, 105 and 150 DAS). As combinations YR + ST (50% and 50%), YR + ST (70% and 30%) and RJ + YR (50% and 50%) provided positive results for agronomic characters and as RJ, RJ + ST (50 % and 50%) and RJ + YR (50% and 50%) for the P content. The phosphate addition, the source reduction and the mixture increased the Mombaça grass.(AU)

Assuntos

RESUMO

In deferred pastures, nitrogen fertilisation and pasture height at the beginning of the deferment period modify the structure and nutritive value of forage. This work was conducted to determine the nitrogen (N) doses and sward heights that were adequate for the deferment of Brachiaria brizantha cv. Marandu syn. Urochloa brizantha cv. Marandu (marandu palisadegrass). Two sward heights (15 and 30 cm) and four N rates (0, 40, 80,120 kg/ha) at the beginning of the deferment period were evaluated in a randomised block design and a factorial scheme with three replications. At the end of the deferment period, the numbers of live and dead tillers, the numbers of tillers with different sizes, the masses of live leaf lamina, dead leaf lamina, live stem and dead stem, the litter mass and the crude protein and neutral detergent fibre contents of the forage were evaluated. With nitrogen fertilisation, there was an increase in the masses of live leaf and live stem in the deferred canopy. With the application of 80 kg/ha of N, the litter mass was higher in the deferred canopy with a height of 30 cm, in relation to that with a height of 15 cm. The highest canopy presented greater stem mass and worse nutritional value when compared to the lowest one. In order to improve forage characteristics, marandu palisadegrass can be deferred by 15 cm and fertilised with 80 kg/ha N. When marandu palisade grass is deferred to 30 cm, nitrogen doses lower than 80 kg/ha can be applied.

Em pastagens diferidas, a adubação nitrogenada e a altura do pasto no inicio do período de diferimento modificam a estrutura e o valor nutritivo da forragem. Esse trabalho foi conduzido para determinar as doses de nitrogênio (N) e as alturas do dossel mais adequadas para o diferimento da Urochloa brizantha cv. Marandu (capim-marandu). Duas alturas do dossel (15 e 30 cm) e quatro doses de N (0, 40, 80,120 kg/ha) no inicio do período de diferimento foram avaliadas, em delineamento de blocos casualizados e esquema fatorial, com três repetições. Ao final do período de diferimento foram avaliados os números de perfilhos vivos e mortos, os números de perfilhos com diferentes tamanhos, as massas de lâmina foliar viva, lâmina foliar morta, colmo vivo e colmo morto; a massa de serrapilheira e os teores de proteína bruta e fibra em detergente neutro da forragem. Com a adubação nitrogenada, houve incremento das massas de lâmina foliar viva e de colmo vivo nos dosséis diferidos. Com aplicação de 80 kg/ha de N, a massa de serrapilheira foi maior no dossel diferido com 30 cm, em relação àquele com 15 cm. O dossel mais alto apresentou maior massa de colmo e pior valor nutritivo, se comparado ao mais baixo. Para melhorar as características da forragem, o capim-marandu pode ser diferido com 15 cm e adubado com 80 kg/ha de N. Quando o capim-marandu é diferido com 30 cm, doses de nitrogênio inferiores a 80 kg/ha podem ser aplicadas.

Assuntos

RESUMO

The deferred pasture structure determines the consumption and performance of grazing animals and, in addition, can be influenced by the duration of the deferment period and nitrogen (N) fertilisation. The objective of this work was to evaluate the structural characteristics of Brachiaria brizantha syn. Urochloa brizantha cv. Piatã (piatã palisadegrass) deferred for two periods (79 and 127 days) and with four N doses (0, 40, 80 and 120 kg ha-1) in the Zona da Mata of Minas Gerais, Brazil. The experimental design involved complete randomised blocks and a subdivided plot scheme, with three replications. The 127-day period of deferment resulted in a higher forage mass, falling index, stem percentage and density, but a lower number of tillers, percentage and volumetric density of live leaf blade. The N dose increment, in general, worsened the structural characteristics of the piatã palisadegrass deferred for 127 days. However, with the 79-day period, the N fertilisation increased the volumetric density of live leaf blades and reduced the stem percentage in the forage mass. As a preliminary recommendation, piatã palisadegrass can be deferred for 79 days and fertilised with up to 90 kg ha-1 of N in the region of Zona da Mata de Minas Gerais, Brazil.

A estrutura do pasto diferido determina o consumo e o desempenho dos animais em pastejo e, ademais, pode ser influenciada pela duração do período de diferimento e pela adubação nitrogenada. O objetivo com este trabalho foi avaliar as características estruturais da Brachiaria brizantha syn. Urochloa brizantha cv. Piatã (capim-piatã) diferida por dois períodos (79 e 127 dias) e com quatro doses de nitrogênio (0, 40, 80 e 120 kg ha-1) na Zona da Mata de Minas Gerais, Brasil. O experimento foi em blocos completos casualizados e em esquema de parcela subdividida, com três repetições. O período de 127 dias de diferimento resultou em maiores massa de forragem, índice de tombamento, porcentagem e densidade volumétrica de colmo, porém em menores número de perfilho, porcentagem e densidade volumétrica de lâmina foliar viva. O incremento da dose de N reduziu a porcentagem de lâmina foliar viva na massa de forragem do capim-piatã diferido por 127 dias. Porém, com o período de 79 dias, a adubação aumentou a densidade volumétrica de lâmina foliar viva e reduziu a porcentagem de colmo na massa de forragem. Como recomendação preliminar, o capim-piatã pode ser diferido por 79 dias e com adubação de até 90 kg ha-1 de N na região da Zona da Mata de Minas Gerais, Brasil.

Assuntos

RESUMO

O fósforo é primordial para as pastagens e a adubação combinada com fontes fosfatadas podem aumentar qualidade nutricional e produtiva do Mombaça. Objetivou-se avaliar as características morfológicas, produtivas e nutricionais do capim Mombaça submetido a combinações de fontes de fósforo solúvel e natural. O delineamento experimental foi o inteiramente casualizado, com dez tratamentos e quatro repetições. Os tratamentos consistiram de três fontes e seis combinações de fontes de fosforo equivalente a 90 kg ha-1 de P2O5, sendo: Controle, Rejeito de rocha fosfática (RJ), Superfosfato triplo (ST), Yoorin Master 1 (YR), RJ + ST (70% e 30%), RJ + ST (50% e 50%), RJ + YR (70% e 30%), RJ + YR (50% e 50%), YR + ST (70% e 30%), YR + ST (50% e 50%). O capim Mombaça foi cultivado durante três cortes (60, 105 e 150 DAS).  As combinações YR + ST (50% e 50%), YR + ST (70% e 30%) e RJ + YR (50% e 50%) proporcionaram resultados positivos para caracteres agronômicos e as fontes RJ, RJ + ST (50% e 50%) e RJ + YR (50% e 50%) para teor de P. A adubação fosfatada, independentemente da fonte e mistura, propiciou incremento no capim Mombaça.

Phosphorus is primordial for pasture and fertilization combined with phosphate sources that can increase the nutritional and productive quality of Mombasa. With that, the objective of this study was to evaluate the morphological, productive and nutritional characteristics of Mombaça grass submitted to combinations of soluble and natural phosphorus sources. The experimental design was randomized with ten treatments and four replications. Controls consist of three sources and six combinations of phosphorus sources equivalent to 90 kg ha-1 of P2O5, namely: Control, Phosphate Rock Tailings (RJ), Triple Superphosphate (ST), Yoorin Master 1 (YR), RJ + ST (70% and 30%), RJ + ST (50% and 50%), RJ + YR (70% and 30%),RJ + YR (50% and 50%), YR + ST (70% and 30) %), YR + ST (50% and 50%). Mombasa grass was grown in three cuts (60, 105 and 150 DAS). As combinations YR + ST (50% and 50%), YR + ST (70% and 30%) and RJ + YR (50% and 50%) provided positive results for agronomic characters and as RJ, RJ + ST (50 % and 50%) and RJ + YR (50% and 50%) for the P content. The phosphate addition, the source reduction and the mixture increased the Mombaça grass.

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Plant-growth-promoting bacteria can be used for sustainable forage grass production while increasing nutrition and biomass. Most of the soils under pasture in the tropics have a degradation level that impairs the forage yield potential, especially because of mismanagement and lack of fertilization. The objective of this work was to evaluate the seed inoculation effects of Azospirillum brasilense on the shoot and root dry mass production and nutritional status of Urochloa brizantha cv. Marandu under field conditions for two years in a fertility soil. The experimental design was a randomized block design with four replications, arranged in a 2 × 3 factorial scheme, comprised of two doses of A. brasilense (0 and 200 mL ha-1) in combination with three doses of N (0, 25 and 50 kg ha-1). Seed inoculation increased shoot dry mass by 13% in the first year and by 6% in the second year, whereas N application increased dry mass by 27% and 35% in the first and second year, respectively. The concentration of nutrients in the shoots did not change due to the inoculation, but N fertilization affected P, Mg, Fe, Mn, and Zn in the first year and N, P and Cu in the second year. Root dry mass increased 36% with fertilization of 25 kg N ha-1 plus inoculation in relation to the other treatments in the first year. In the second year, the inoculation of A. brasilense increased by 17%. Therefore, seed inoculation of Urochloa brizantha cv. ‘Marandu with Azospirillum brasilense increased root and shoot dry mass production in some cuts without influencing tiller numbers. Nitrogen fertilization altered N, Mg, P, Fe, Mn, Zn, and Cu concentrations in shoot dry mass.(AU)

As bactérias promotoras de crescimento de plantas podem ser usadas para a produção sustentável de gramíneas forrageiras, aumentando a nutrição e a biomassa. A maioria dos solos sob pastagem nos trópicos apresenta um certo nível de degradação que prejudica o potencial de produção de forragem, principalmente por causa de má gestão e falta de fertilização. O objetivo deste trabalho foi avaliar os efeitos da inoculação de sementes de Azospirillum brasilense na produção de massa seca da parte aérea e da raiz e o estado nutricional do Urochloa brizantha cv. Marandu sob condições de campo por dois anos em um solo de de baixa fertilidade. O delineamento experimental foi em blocos casualizados com quatro repetições, dispostos em esquema fatorial 2 × 3, composto por duas doses de A. brasilense (0 e 200 mL ha-1) em combinação com três doses de N (0, 25 e 50 kg ha-1). A inoculação das sementes aumentou a massa seca da parte aérea em 13% no primeiro ano e em 6% no segundo ano, enquanto a aplicação de N aumentou 27% e 35% no primeiro e segundo ano, respectivamente. A concentração de nutrientes na parte aérea não foi alterada devido à inoculação, porém a adubação nitrogenada afetou P, Mg, Fe, Mn e Zn no primeiro ano e N, P e Cu no segundo ano. A massa seca da raiz aumentou 36% com a adubação de 25 kg N ha-1 combinado com a inoculação em relação aos demais tratamentos, no primeiro ano. No segundo ano, a inoculação de A. brasilense aumentou em 17%. Portanto, a inoculação de sementes de Urochloa brizantha cv. ‘Marandu com o Azospirillum brasilense aumentou a produção de massa seca da raiz e da parte aérea em alguns cortes sem influenciar o número de perfilhos. A adubação nitrogenada alterou as concentrações de N, Mg, P, Fe, Mn, Zn e Cu da massa seca da parte aérea.(AU)

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Plant-growth-promoting bacteria can be used for sustainable forage grass production while increasing nutrition and biomass. Most of the soils under pasture in the tropics have a degradation level that impairs the forage yield potential, especially because of mismanagement and lack of fertilization. The objective of this work was to evaluate the seed inoculation effects of Azospirillum brasilense on the shoot and root dry mass production and nutritional status of Urochloa brizantha cv. Marandu under field conditions for two years in a fertility soil. The experimental design was a randomized block design with four replications, arranged in a 2 × 3 factorial scheme, comprised of two doses of A. brasilense (0 and 200 mL ha-1) in combination with three doses of N (0, 25 and 50 kg ha-1). Seed inoculation increased shoot dry mass by 13% in the first year and by 6% in the second year, whereas N application increased dry mass by 27% and 35% in the first and second year, respectively. The concentration of nutrients in the shoots did not change due to the inoculation, but N fertilization affected P, Mg, Fe, Mn, and Zn in the first year and N, P and Cu in the second year. Root dry mass increased 36% with fertilization of 25 kg N ha-1 plus inoculation in relation to the other treatments in the first year. In the second year, the inoculation of A. brasilense increased by 17%. Therefore, seed inoculation of Urochloa brizantha cv. ‘Marandu’ with Azospirillum brasilense increased root and shoot dry mass production in some cuts without influencing tiller numbers. Nitrogen fertilization altered N, Mg, P, Fe, Mn, Zn, and Cu concentrations in shoot dry mass.

As bactérias promotoras de crescimento de plantas podem ser usadas para a produção sustentável de gramíneas forrageiras, aumentando a nutrição e a biomassa. A maioria dos solos sob pastagem nos trópicos apresenta um certo nível de degradação que prejudica o potencial de produção de forragem, principalmente por causa de má gestão e falta de fertilização. O objetivo deste trabalho foi avaliar os efeitos da inoculação de sementes de Azospirillum brasilense na produção de massa seca da parte aérea e da raiz e o estado nutricional do Urochloa brizantha cv. Marandu sob condições de campo por dois anos em um solo de de baixa fertilidade. O delineamento experimental foi em blocos casualizados com quatro repetições, dispostos em esquema fatorial 2 × 3, composto por duas doses de A. brasilense (0 e 200 mL ha-1) em combinação com três doses de N (0, 25 e 50 kg ha-1). A inoculação das sementes aumentou a massa seca da parte aérea em 13% no primeiro ano e em 6% no segundo ano, enquanto a aplicação de N aumentou 27% e 35% no primeiro e segundo ano, respectivamente. A concentração de nutrientes na parte aérea não foi alterada devido à inoculação, porém a adubação nitrogenada afetou P, Mg, Fe, Mn e Zn no primeiro ano e N, P e Cu no segundo ano. A massa seca da raiz aumentou 36% com a adubação de 25 kg N ha-1 combinado com a inoculação em relação aos demais tratamentos, no primeiro ano. No segundo ano, a inoculação de A. brasilense aumentou em 17%. Portanto, a inoculação de sementes de Urochloa brizantha cv. ‘Marandu’ com o Azospirillum brasilense aumentou a produção de massa seca da raiz e da parte aérea em alguns cortes sem influenciar o número de perfilhos. A adubação nitrogenada alterou as concentrações de N, Mg, P, Fe, Mn, Zn e Cu da massa seca da parte aérea.

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BACKGROUND: Great efforts have been made to identify grasses that are resistant to spittlebugs (Hemiptera: Cercopidae). However, the time required to develop and launch new cultivars is relatively long. The employment of resistance inducers is a current strategy that may be useful for the control of insect pests. This analysis evaluates the feasibility of using the chemical inducers silicon and nitric oxide to increase spittlebug resistance based on changes in forage grass vegetative characteristics and the biological traits of Mahanarva spectabilis (Distant, 1909). RESULTS: Mahanarva spectabilis nymphs and adults can cause significant damage to forage grasses. Furthermore, silicon and nitric oxide inducers were not sufficient to lessen this damage by positively influencing the growth and development of forage grasses. These inducers did not negatively alter the biological parameters of M. spectabilis or diminish its population. However, phenolic compound concentrations increased when forage grasses were treated with silicon or attacked by adult insects, but this parameter was not useful to predict spittlebug resistance. This fact suggests that the physiological and biochemical changes caused by silicon should be further studied. CONCLUSION: The current analysis demonstrated that application of the chemical inducers silicon and nitric oxide is currently not a viable strategy for the effective and economic management of M. spectabilis on Brachiaria ruziziensis, Pennisetum purpureum and Digitaria sp. © 2019 Society of Chemical Industry.

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This study aimed to evaluate aspects of reproductive phenology, yield components and seed quality of the B4 genotype of Brachiaria brizantha in function of nitrogen doses applied at pre-flowering. The experiment was carried out at Embrapa Beef Cattle, in a randomized block design, with seeding density of 2.59kg SPV ha-1 in the first year, in free growth plants. Urea was applied at pre-flowering at doses of 0, 25, 50, 75, 100, 125 and 150kg ha-1. The reproductive cycle of the plant lasts 225 days, with late flowering. N doses influenced the following characteristics: number of fully expanded inflorescences, percentage of dry matter, dry biomass, number of spikelets per raceme, seed yield, weight of a thousand seeds, germination, germination speed index, viability and germination at 10 months after harvest. The maximum yield of pure seed was 144.8kg ha-1 for 50kg ha-1 N, with maximum biological potential, based on components of seed yield of 456.27kg ha-1. Seeds presented high dormancy and reduced physiological quality in higher N doses.(AU)

Objetivou-se avaliar aspectos da fenologia reprodutiva, componentes do rendimento e qualidade de sementes do genótipo B4 de Brachiaria brizantha em função de doses de nitrogênio aplicado no pré-florescimento. O experimento foi conduzido na Embrapa Gado de Corte, em blocos casualizados, densidade de semeadura de 2,59kg SPV ha-1, em plantas de primeiro ano e em crescimento livre. Ureia foi aplicada no pré-florescimento nas doses 0, 25, 50, 75, 100, 125 e 150kg ha-1. O ciclo reprodutivo da planta foi de 225 dias, com florescimento tardio. Doses de N influenciaram o número de inflorescências totalmente emergidas, porcentagem de matéria seca, biomassa seca, número de espiguetas por racemo, produtividade de sementes puras, peso de mil sementes, germinação, índice de velocidade de germinação, viabilidade e germinação aos 10 meses da colheita. A produtividade máxima de sementes puras foi 144,8kg ha-1 para 50kg ha-1 N, com potencial biológico máximo, baseado nos componentes da produção de sementes de 456,27kg ha-1. As sementes apresentaram dormência elevada e redução na qualidade fisiológica nas maiores doses de N.(AU)

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It is important to know the mechanisms for forage development, especially those related to the tolerance of potentially toxic elements, when considering their use in phytoremediation in heavy metal contaminated areas. In this study, we evaluated plant growth, concentration, and the availability of cadmium (Cd) for forage grasses (Panicum maximum Jacq. cv. Aruana and cv. Tanzânia; Brachiaria decumbens cv. Basilisk; Brachiaria brizantha cv. Xaraés and cv. Marandu) cultivated in Cd contaminated soils. The experiments were performed under greenhouse conditions over a 90-day evaluation period, and the Cd rates were 2, 4, and 12 mg/kg of soil. The relative growth rate of the forage grasses decreased as Cd rates increased, and the following descending order of susceptibility was observed: Marandu > Xaraés > Aruana > Tanzânia > Basilisk, with regard to phytotoxicity in these plants. The forage Cd concentration increased in line with increases in the Cd rates. Cd contents extracted by Mehlich-1 and by diethylenetriaminepentaacetic acid presented high positive correlation with forage relative growth. The forage plants did not block Cd entry into the food chain because they were not capable of limiting Cd absorption.

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This study investigated two industrial by-products - red mud (RM) and its mixture with phosphogypsum (RMG), as amendments in an As((5+))-contaminated soil from a gold mining area in Brazil in order to grow three plant species: Brachiaria decumbens, Crotalaria spectabilis, and Stylosanthes cv. Campo Grande. These amendments were applied to reach a soil pH of 6.0. Using RM and RMG increased shoot dry matter (SDM) and root dry matter (RDM) of most plants, with RMG being more effective. Adding RMG increased the SDM of Brachiaria and Crotalaria by 18 and 25% and the RDM by 25 and 12%, respectively. Stylosanthes was sensitive to As toxicity and grew poorly in all treatments. Arsenic concentration in shoots of Brachiaria and Crotalaria decreased by 26% with the use of RMG while As in roots reduced by 11 and 30%, respectively. Also, the activities of the plant oxidative stress enzymes varied following treatments with the by-products. The plants grew in the As-contaminated soil from the gold mining area. Thus, they might be employed for phytoremediation purposes, especially with the use of RMG due to its potential advantage in terms of nutrient supply (Ca(2+) and SO4(2-) from phosphogypsum).

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Natural phytotoxins and their synthetic analogs are a potential source of new bioactive compounds for agriculture. Analogs of rubrolides, a class of γ-alkylidene-γ-lactones isolated from different ascidians, have been shown to interfere with the photosynthetic electron-transport chain, yet their activity needs to be improved. With this aim, ten 5-aryl-6-benzyl-4-bromopyridazin-3(2H)-ones were prepared in yields ranging from 44 to 88% by reaction of their correspondent γ-alkylidene-γ-lactones with NH2 NH2 . The structures of these rubrolide analogs were determined by (1) H- and (13) C-NMR, 2D-NMR (COSY and HETCOR), NOE difference, and MS techniques. These compounds were evaluated for their abilities of interfering with the light-driven reduction of ferricyanide by isolated spinach chloroplasts. Lactones with electron-withdrawing substituents in the para-position of the benzylidene ring were the most effective inhibitors. Characterization of the activity of 11b/11b' suggested a mechanism based on the interaction with the plastoquinone binding site of photosystem II. Addition of several compounds to the culture medium of a cyanobacterial model strain was found to inhibit algal growth. However, the relative effectiveness was not consistent with their activity in vitro, suggesting the occurrence of multiple targets and/or detoxyfication mechanisms. Indeed, the compounds showed differential effects on the heterotrophic growth of some crop species, Cucumis sativus and Sorghum bicolor. Pyridazin-3(2H)-ones 12e, 12i, and 12j, which have been found poorly active against the photosynthetic electron transport, were the most effective in inhibiting the growth of some weeds, Ipomoea grandifolia and Brachiaria decumbens, under greenhouse conditions.

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Nitrogen fertiliser accelerates plant growth and increases herbage utilisation efficiency in continuously stocked temperate grass swards, indicating greater herbage production and harvest efficiency. There is no similar evidence, however, for tropical pastures. In this study we evaluated the morphogenetic responses, the patterns of defoliation and the efficiency of herbage utilisation of continuously stocked marandu palisade grass (Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. cv. Marandu) maintained at 30 cm by cattle and fertilised with nitrogen. Treatments corresponded to four measures of nitrogen application (0, 150, 300 and 450 kg ha1), and were assigned to experimental units (1,200 m2 paddocks) according to a randomised complete block design, with four replications. There was a seasonal pattern of variation in the morphogenetic responses and in herbage utilisation efficiency (HUE) characterised by higher herbage growth rates and HUE during late spring and summer. Nitrogen fertilisation increased both leaf appearance and elongation rates (around 60 % between non-fertilised and swards fertilised with 450 kg ha1, p 0.05), requiring higher stocking rates (average of 1.6, 2.6, 2.9 and 3.1 Animal Unit (adult animal weighing 450 kg) ha1 for 0, 150, 300 and 450 kg ha1, respectively) to maintain the management target. Although the frequency of leaf defoliation increased (with no change in defoliation severity - 56.1 ± 1.88 %), the leaf lifespan decreased, resulting in a similar number of defoliations during the leaf lifespan (average of 0.91 ± 0.069). This resulted in increased HUE only for the 150 kg ha1 treatment relative to non-fertilisation (37.5, 48.1, 44.0 and 44.5 ± 2.25 % for 0, 150, 300 and 450 kg ha1 N, respectively), indicating that with nitrogen fertilisation rates above 150 kg ha1, there are compensatory mechanisms related to morphogenetic responses that buffer changes in utilisation efficiency.(AU)

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