RESUMO Os percevejos-das-gramíneas [Blissus pulchellus Montandon (Hemiptera: Blissidae)] sugam a seiva de espécies forrageiras suscetíveis e injetam toxinas que destroem os vasos condutores e dificultam o transporte de água e nutrientes, levando as plantas a morte. Assim, o objetivo deste estudo foi avaliar a resistência por antixenose e tolerância em oito poáceas forrageiras à B. pulchellus e comparar as características anatômicas dos tecidos das bainhas foliares de espécies/cultivares resistentes e suscetíveis. Os ensaios foram conduzidos em laboratório e casa de vegetação, em testes com e sem chance de escolha, utilizando-se as forrageiras: Urochloa ruziziensis, U. humidicola, U. brizantha ‘Piatã’, U. brizantha ‘Paiaguás’, U. brizantha ‘Marandu’, Panicum maximum ‘Mombaça’, P. maximum ‘Zuri’, e Andropogon gayanus. Os resultados de oviposição demonstraram que no teste de escolha houve uma mudança no comportamento do percevejo em relação às gramíneas quatro horas após infestação, sendo U. humidicola, P. maximum ‘Mombaça’ e ‘Zuri’, U. brizantha ‘Marandu’ e A. gayanus menos atrativos para os insetos. Conclui-se que U. humidicola, P. maximum ‘Mombaça’ e ‘Zuri’, U. brizantha ‘Marandu’, e A. gayanus são menos atrativas a B. pulchellus. A. gayanus, e P. maximum ‘Mombaça’ e ‘Zuri’ apresentam resistência do tipo não-preferência para oviposição a B. pulchellus. A resistência de U. humidicola, P. maximum Zuri, e A. gayanus a B. pulchellus pode estar associada a maior compactação e lignificação das células dos tecidos parenquimático e esclerenquimático das bainhas foliares.

ABSTRACT Chinch bugs [Blissus pulchellus Montandon (Hemiptera: Blissidae)] suck the phloem from susceptible forage grasses, injecting toxins that destroy plant vessels and compromise the flow of water and nutrients, leading to plant death. Thus, the aim of this study was to assess eight forage grasses for antixenosis resistance to B. pulchellus and compare the anatomical characteristics of leaf sheath tissue from resistant and susceptible species/cultivars. Experiments were conducted in a laboratory and greenhouse, using choice and no-choice tests with the following forage grasses: Urochloa ruziziensis, U. humidicola, U. brizantha ‘Piatã’, U. brizantha ‘Paiaguás’, U. brizantha ‘Marandu’, Panicum maximum ‘Mombaça’, P. maximum ‘Zuri’, and Andropogon gayanus. The oviposition results demonstrated that in the choice test there was a change in the stink bug’s behavior in relation to grasses four hours after infestation, with U. humidicola, P. maximum ‘Mombaça’ and ‘Zuri’, U. brizantha ‘Marandu’ and A. gayanus, proving to be less attractive to insects. It is concluded that U. humidicola, P. maximum ‘Mombaça’ and ‘Zuri’, U. brizantha ‘Marandu’, and A. gayanus are less attractive to B. pulchellus. A. gayanus and P. maximum ‘Mombaça’ and ‘Zuri’ showed non-preference resistance (antixenosis) to oviposition by B. pulchellus. The resistance of U. humidicola, P. maximum ‘Zuri’, and A. gayanus to B. pulchellus may be associated with greater compaction and lignification of the parenchyma and sclerenchyma cells of leaf sheaths.

Resumo O crescimento das plantas é severamente reduzido devido ao estresse hídrico, afetando a fotossíntese, incluindo a atividade do fotossistema II (PSII) e o transporte de elétrons. Este estudo enfatizou as mudanças comparativas e prioritárias na atividade do PSII devido à seca progressiva em sete populações de Panicum antidotale (P. antidotale) coletadas no Deserto do Cholistão e regiões fora do Cholistão. Perfilhos de igual crescimento de sete populações de P. antidotale cultivadas em vasos de plástico cheios de solo foram submetidos à seca progressiva, retendo a irrigação com água por três semanas. A seca progressiva reduziu o teor de umidade do solo, teor de água relativo nas folhas, pigmentos fotossintéticos e biomassa fresca e seca dos brotos em todas as sete populações. Populações de Dingarh Fort, Dingarh Grassland e Haiderwali tiveram maior crescimento do que as de outras populações. As populações de Cholistani, especialmente em Dingarh Grassland e Haiderwali, apresentaram maior capacidade de ajuste osmótico, refletido pelo potencial osmótico e maior acúmulo de proteínas solúveis totais. H2O2 máximo sob estresse hídrico foi observado em populações de Muzaffargarh e Khanewal, mas estas foram intermediárias no conteúdo de MDA. Sob estresse hídrico, as populações de Muzaffargarh e Dingarh Fort tiveram maior acúmulo de K+ em suas folhas. Durante a seca progressiva, as populações não cholistanesas mostraram rolagem completa das folhas após 23 dias de seca, e essas populações não conseguiram suportar mais condições de estresse hídrico, enquanto as populações cholistani toleraram mais condições de estresse hídrico por 31 dias. Além disso, a seca progressiva causou danos ao PSII após 19 dias e tornou-se severa após 23 dias em populações não cholistanesas de P. antidotale do que em populações cholistanesas.

Abstract Growth of plants is severely reduced due to water stress by affecting photosynthesis including photosystem II (PSII) activity and electron transport. This study emphasised on comparative and priority targeted changes in PSII activity due to progressive drought in seven populations of Panicum antidotale (P. antidotale) collected from Cholistan Desert and non-Cholistan regions. Tillers of equal growth of seven populations of P. antidotale grown in plastic pots filled with soil were subjected progressive drought by withholding water irrigation for three weeks. Progressive drought reduced the soil moisture content, leaf relative water content, photosynthetic pigments and fresh and dry biomass of shoots in all seven populations. Populations from Dingarh Fort, Dingarh Grassland and Haiderwali had higher growth than those of other populations. Cholistani populations especially in Dingarh Grassland and Haiderwali had greater ability of osmotic adjustment as reflected by osmotic potential and greater accumulation of total soluble proteins. Maximum H2O2 under water stress was observed in populations from Muzaffargarh and Khanewal but these were intermediate in MDA content. Under water stress, populations from Muzaffargarh and Dingarh Fort had greater K+ accumulation in their leaves. During progressive drought, non-Cholistani populations showed complete leaf rolling after 23 days of drought, and these populations could not withstand with more water stress condition while Cholistani populations tolerated more water stress condition for 31 days. Moreover, progressive drought caused PSII damages after 19 days and it became severe after 23 days in non-Cholistani populations of P. antidotale than in Cholistani populations.

RESUMO O trabalho analisa a viabilidade econômica de essências florestais, exóticas e nativas da caatinga, cultivadas em sistemas silvipastoris, consorciados a cultura forrageira do capim Tanzânia, comparados aos de monocultivo florestal, utilizando-se do crédito de carbono como alternativa de renda extra, visando retorno econômico na venda da madeira em pé para produção de lenha. O experimento foi conduzido na estação Experimental do Pernambuco Agricultural Research Institute (IPA), no município de Belém do São Francisco, localizado na região Semiárida do estado de Pernambuco, Microrregião de Itaparica. Foram escolhidos quatro cultivos arbóreos, sendo eles dois nativos do bioma Caatinga: o Angico (Anadenanthera colubrina var. Cebil), a Aroeira (Myracrodruon urundeuva Allemão), e dois clones exóticos de eucalipto, E. urophylla x E. tereticornis. Em relação a forrageira, foi escolhido o capim Tanzânia (Panicum maximum Jacq). Os consórcios agrícolas do capim Tanzânia, com os dois clones de eucaliptos, apresentaramse viáveis economicamente em todos os parâmetros econômicos analisados, sendo esse o mais indicado na comercialização da madeira em pé para produção de lenha. Não é recomendável economicamente a venda da madeira em pé para produção de lenhas no sistema de monocultivo e no silvipastoril com as espécies nativas do Angico e da Aroeira aos 96 meses de idade, devido a inviabilidade econômica do sistema. Agregando a possibilidade de crédito financeiro, mediante ao carbono atmosférico sequestrado pelas árvores, é possível viabilizar economicamente todos os custos dos cultivos florestais em sistemas silvipastoris e em monocultivo.

ABSTRACT This study analyzes the economic viability of exotic and native caatinga forest species grown in silvopastoral systems, combined with the Guinea grass forage crop, compared to monoculture forestry systems, using carbon credits as an alternative source of extra income, aiming for an economic return on the sale of standing timber for firewood production. The experiment was conducted at the Experimental Station of the Pernambuco Agricultural Research Institute (IPA) in Belém do São Francisco, located in the semi-arid region of the state of Pernambuco, in the Itaparica micro region. Four tree crops were chosen, two of which are native to the Caatinga biome: Angico (Anadenanthera colubrina var. Cebil) and Aroeira (Myracrodruon urundeuva Allemão), and two exotic eucalyptus clones, E. urophylla x E. tereticornis. Guinea grass (Panicum maximum Jacq) was chosen as the forage. The intercropping of Guinea grass with the two eucalyptus clones proved to be economically viable in all the economic parameters analyzed, and this is the most suitable for marketing standing wood for firewood production. It is not economically advisable to sell the standing wood for firewood production in the monoculture and silvopastoral systems with the native species (Angico and Aroeira) at 96 months of age due to the system's economic unfeasibility. By adding the possibility of financial credit through the atmospheric carbon sequestered by the trees, it is possible to make all the costs of forestry crops in silvopastoral and monoculture systems economically viable.

ABSTRACT Effluent from fish farming with saline water is a source of water, also rich in organic matter and nutrients, that can be used in irrigation of cultivated plants and even fully or partially replace mineral fertilization. The objective was to evaluate the growth, biomass production and quality of P. maximum cultivars fertigated with fish farming effluent in a greenhouse experiment, using a randomized block design with eight replicates. Treatments were arranged in a split-split-plot scheme, with three irrigation managements in the plot (irrigation with public-supply water, irrigation with public-supply water + conventional fertilization, and irrigation with fish farming effluent), three cultivars of P. maximum (Tanzania, Mombasa, and Massai) in the sub-plot, and four cutting times in the sub-sub-plot (45, 90, 135, and 180 days after sowing). Plant height, number of tillers, production of fresh biomass, neutral detergent fiber, acid detergent fiber, ether extract, crude protein, dry matter, and mineral matter contents were analyzed. The highest growth, production, and quality of P. maximum grass occurs when irrigated with public-supply water and under conventional NPK fertilization. Fertigation with fish farming effluent reduces the growth and production of P. maximum grass, but allows obtaining better quality forage. It is possible to irrigate P. maximum grass using fish farming effluent with satisfactory yields. The growth of cv. Massai was more sensitive to irrigation with fish farming effluent than those of the cultivars Tanzania and Mombasa.

RESUMO O capim-colonião (Megathyrsus maximus) é amplamente utilizado como cultura forrageira no Brasil, mas sua produção enfrenta ameaças de doenças. Recentemente, novos sintomas, como lesões marrons oblongas a irregulares nas folhas, surgiram em M maximus em todo o país. Sintomas particularmente severos foram observados na cultivar BRS Tamani, e alguns outros genótipos apresentaram coalescência de lesões e intensa necrose foliar. Objetivou-se identificar a causa desses sintomas. Um fungo foi isolado das lesões e, por meio de medidas morfológicas e análise molecular dos genes ITS, GPDH e TEF-1α, identificado como Bipolaris yamadae. Testes de patogenicidade confirmaram sua capacidade de causar doença em M. maximus cv. Tamani. Um levantamento de campo com 205 genótipos de M maximus revelou sintomas severos em 8,35 % dos materiais.

ABSTRACT Guinea grass (Megathyrsus maximus) is widely used as a forage crop in Brazil, but its production faces disease threats. Recently, new symptoms, such as oblong to irregular brown lesions on leaves, have emerged in M. maximus across the country. Particularly severe symptoms were observed in the BRS Tamani cultivar, and some other genotypes showed lesion coalescence and intense leaf necrosis. This study aimed to identify the cause of these symptoms. A fungus was isolated from the lesions and, using morphological measurements and molecular analysis of the ITS, GPDH and TEF-1α genes, it was identified as Bipolaris yamadae. Pathogenicity tests confirmed its ability to cause disease in M. maximus cv. Tamani. A field survey of 205 M maximus genotypes showed severe symptoms in 8.35 % of the materials.

Resumen Introducción. Profundizar en los efectos alopáticos de las arvenses sobre los cultivos agrícolas y sobre otras arvenses, resulta de gran importancia para establecer estrategias de manejo. Objetivo. Evaluar el efecto alelopático de residuos de rizomas de Panicum maximum Jacq. sobre Euphorbia heterophylla L. y Amaranthus dubius Mart. en pre y pos-emergencia. Materiales y métodos. Se realizaron cuatro ensayos en diseños completamente al azar 5x5 en el Laboratorio de Sanidad Vegetal de Cienfuegos, Cuba, en el año 2020. Se evaluó la capacidad alelopática de residuos de rizoma de la planta P. maximum contra E. heterophylla y A. dubius en aplicaciones previo a la emergencia o emergencia (pre-emergencia) y después de la emergencia (pos-emergencia). Se evaluaron cinco tratamientos 0, 40, 60, 80 y 100 g de rizomas fraccionados de plantas de P. máximum por 2 kg de suelo, con cinco repeticiones (potes plásticos). Para la obtención de los rizomas, se tomaron plantas en fase de floración y fructificación a los tres meses de edad. A los 12 días desde el tratamiento se comparó el porcentaje de emergencia y/o sobrevivencia, la longitud de la radícula y del hipocótilo. Se realizaron análisis de varianzas y comparación de medias con la prueba de Tukey (p≤0,05), con el uso de SPSS (vers. 15). Resultados. Al compararse el efecto de los tratamientos contra E. heterophylla, se observó reducción significativa de la emergencia en pre-emergencia y una disminución del porcentaje de la sobrevivencia y de la longitud del hipocótilo significativas en pos-emergencia, mientras que contra A. dubius hubo una reducción de la emergencia y sobrevivencia y disminución significativa de la longitud de la radícula y del hipocótilo en pre y pos-emergencia. Conclusiones. Se verificó el efecto alelopático negativo (P<0,05) de los residuos de P. maximum sobre E. heterophylla y A. dubius.

Abstract Introduction. Delving into the allopathic effects of weeds on agricultural crops and other weeds is of great importance in establishing management strategies. Objective. To evaluate the allelopathic effect of residues from Panicum maximum Jacq. rhizomes on Euphorbia heterophylla L. and Amaranthus dubius Mart. in pre and post-emergence. Materials and methods. Four experiments were conducted in completely randomized design 5x5 at the Plant Health Laboratory in Cienfuegos, Cuba, in 2020. The allelopathic capacity of P. maximum rhizome residues against E. heterophylla and A. dubius was evaluated in pre-emergence and post-emergence applications. Five treatments were assessed: 0, 40, 60, 80, and 100 g of P. maximum plants rhizomes fractioned per 2 kg of soil, with five repetitions (plastic pots). Rhizomes were obtained from plants in the flowering and fruiting stage at three months of age. At 12 days from the treatment, the percentage of emergence and/or survival, radicle, and hypocotyl length were compared. Analysis of variance and mean comparisons using Tukey's test (p≤0.05) were performed using SPSS (vers. 15). Results. When comparing the treatment effect against E. heterophylla, a significant reduction in emergence in pre-emergence and a decrease in survival percentage and hypocotyl length in post-emergence were observed, while against A. dubius, there was a reduction in emergence and survival, and a significant decrease in radicle and hypocotyl length pre and post-emergence. Conclusions. The negative allelopathic effect (P<0.05) of P. maximum residues on both E. heterophylla and A. dubius was confirmed.

RESUMO O consórcio entre milho e espécies forrageiras é uma alternativa comumente utilizada dentro dos sistemas agropecuários. A competição entre as culturas pode ser um fator limitante no consórcio, comprometendo a produção do milho e forragem. Embora necessário, a interação de forrageiras lançadas no mercado nos últimos anos, como a BRS Zuri consorciada com a cultura do milho, não fornece respostas satisfatórias na literatura. Por isso, técnicas como a utilização de subdoses de herbicida entra com uma opção a fim de suprimir o crescimento da forrageira, viabilizando o cultivo simultâneo. Assim, objetivou-se no presente estudo avaliar os efeitos de subdoses do herbicida glyphosate sobre o desenvolvimento de Panicum maximum cv. BRS Zuri consorciado com milho RR (Roundup Ready®) e como essa interação reflete na população de plantas daninhas, no rendimento da forrageira e nas variáveis biométricas e produtivas do milho. O delineamento foi em blocos casualizados, cujos tratamentos consistiram em seis subdoses do herbicida glyphosate (0, 48, 96, 240, 480 e 960 g equivalente ácido [e.a.] ha-1), além do milho em monocultivo com quatro repetições. Para as condições do presente estudo, a dose de 480 g e.a. ha-1 de glyphosate pode ser uma alternativa, visto que houve a supressão de plantas daninhas e um adequado desenvolvimento da forragem. Já o rendimento do milho não foi afetado pela presença da forrageira.

ABSTRACT The intercropping between maize and forage species is an alternative commonly used within farming systems. Competition among crops may be a limiting factor in intercropping, compromising maize and forage yield. Although necessary, the literature does not provide satisfactory answers on the interaction of forage crops launched in the market recently, such as BRS Zuri, intercropped with maize. Therefore, techniques such as the use of herbicide subdoses come in as an option to suppress forage growth, making simultaneous cultivation feasible. Thus, the present study aimed to evaluate the effects of glyphosate herbicide subdoses on the development of Panicum maximum cv. BRS Zuri intercropped with Roundup Ready® (RR) maize and how this interaction reflects on the weed population, forage yield, and biometric and yield variables of maize. The experimental design was randomized blocks with treatments consisting of six subdoses of glyphosate herbicide (0, 48, 96, 240, 480, and 960 g acid equivalent [a.e.] ha-1) and maize in monoculture with four replications. For the conditions of this study, the dose of 480 g a.e. ha-1 of glyphosate may be an alternative since there was weed suppression and adequate forage development. Maize yield was not affected by the presence of forage.

Resumen Para evaluar el efecto de la incorporación de L. leucocephala sobre la producción de biomasa y la composición química de P. maximum cv. Tanzania en un sistema silvopastoril, se estableció un experimento en dos praderas, establecidas con P. maximum cv. Tanzania como único cultivo en una de ellas y en la otra asociada con L. leucocephala en un arreglo de pasturas en callejones. En cada pradera fueron colocadas 12 jaulas de exclusión de 1 m3 en un diseño completamente al azar con arreglo factorial 2 x 4, dos sistemas (monocultivo y silvopastoril) y cuatro fechas de corte (28, 56, 84 y 112 d) y tres repeticiones. Se aplicó una fertilización química con Fosfonitrato en cada una de las jaulas de exclusión para ambos tratamientos. Se observó diferencia significativa entre sistemas para las variables altura, cobertura, producción de materia orgánica (kg/ha), producción de proteína cruda (kg/ha) y el porcentaje de FDN, reportando los mejores valores el sistema silvopastoril. Se concluye que el uso de la Leucaena ofrece ventajas importantes si se considera que es capaz de producir alimento de alto valor nutricional para los animales, además, mejora la calidad y cantidad de forraje del sistema.

Abstract To evaluate the effect of L. leucocephala incorporation on P. maximum cv. Tanzania biomass production and chemical composition of in a silvopastoral system, an experiment was established in two grasslands, established with P. maximum cv. Tanzania as the only crop in one of them and in the other, associated with L. leucocephala in an arrangement of pastures in alleys. In each meadow, 12 exclusion cages of 1 m3 were placed in a completely random design with a 2 x 4 factorial arrangement, two systems (monoculture and silvopastoral) and four cutting dates (28, 56, 84 and 112 d) and three repetitions. Chemical fertilization with Phosphonitrate was applied in each of the exclusion cages for both treatments. A significant difference was observed between systems for the variables height, coverage, production of organic matter (kg/ha), production of crude protein (kg/ha) and the percentage of FDN, reporting the best values of the silvopastoral system. It is concluded that the use of Leucaena offers important advantages if we consider its capability for producing food of high nutritional value for animals, as well as it improving the forage quality and quantity of the system.

Resumen El pasto Panicum maximum cv. BRS Tamani es una planta forrajera híbrida de alta calidad, de tamaño pequeño y con intensa actividad de macollaje. Este estudio se llevó a cabo para examinar el potencial del pasto Panicum maximum cv. BRS Tamani en diferentes edades de rebrote (49, 63, 77 y 91 días) para la producción de heno, en el período lluvioso. El experimento se realizó en la Escuela Agrícola de la Universidad Federal de Mato Grosso do Sul-Brasil, entre octubre de 2015 y abril de 2016. Los tratamientos correspondieron a cuatro edades de rebrote, con cuatro repeticiones, distribuidas en parcelas de 9 m2. Las edades de rebrote influyeron en las características morfogenéticas del pasto, excepto por la senescencia de la hoja y la longitud final de la hoja. Los rendimientos de materia verde (9.6-17.6 t ha-1) y seca (2.6-5.9 t ha-1), el rendimiento de heno (3.4-6.9 t ha-1) y las proporciones de tallo (91.6-455.9 g kg-1) y material senescente (34.8-98.4 g kg-1) aumentaron con las edades de rebrote, mientras que la proporción de hojas (837.7-402.1 g kg-1) y la relación hoja:tallo (15.9-0.9) disminuyeron (P<0.05). Los contenidos de materia seca (881.7-852.8 g kg-1) y de proteína (81.2-47.6 g kg-1) del heno disminuyeron con las mayores edades de rebrote; sin embargo, los contenidos de fibra detergente neutro (746.5-759.2 g kg-1), fibra detergente ácido (519.8-567.7 g kg-1) y lignina (74.3-86.4 g kg-1) aumentaron a medida que lo hicieron las edades de rebrote. La digestibilidad de los nutrientes disminuyó con las edades de rebrote (P<0.05). Panicum maximum cv. BRS Tamani tiene el potencial de producir heno ha-1, mejor valor nutritivo y una alta proporción de hojas en el intervalo de rebrote de 49 a 63 días.

Abstract The grass Panicum maximum cv. BRS Tamani is a hybrid high-quality, small-sized forage plant with intense tillering activity. This study was carried out to examine the potential of the grass Panicum maximum cv. BRS Tamani at different regrowth ages (49, 63, 77, and 91 d) for hay production, in the rainy period. The experiment was conducted at the Farm School of the Federal University of Mato Grosso do Sul-Brazil, between October 2015 and April 2016. The treatments corresponded to four regrowth ages, with four replicates, distributed into 9 m2 plots. Regrowth ages influenced the morphogenetic characteristics of the grass, except for leaf senescence and final leaf length. Green (9.6-17.6 t ha-1) and dry-matter (2.6-5.9 t ha-1) yields, hay yield (3.4-6.9 t ha-1), and proportions of stem (91.6-455.9 g kg-1) and senescent material (34.8-98.4 g kg-1) increased with the regrowth ages, while the proportion of leaves (837.7-402.1 g kg-1) and the leaf: stem ratio (15.9-0.9) decreased (P<0.05). The dry matter (881.7-852.8 g kg-1) and protein contents (81.2-47.6 g kg-1) of the hay decreased with the higher regrowth ages; however, the neutral detergent fibre (746.5-759.2 g kg-1) acid detergent fibre (519.8-567.7 g kg-1) and lignin (74.3-86.4 g kg-1) contents rose as the regrowth ages did. Nutrient digestibility decreased with the regrowth ages (P<0.05). Panicum maximum cv. BRS Tamani has the potential to produce of hay ha-1, better nutritive value and a high proportion of leaves in the regrowth interval of 49 to 63 d.

Resumen El objetivo del estudio fue evaluar el valor nutricional de dietas de Panicum maximum suplementadas con 30% de follajes arbóreos mezclados con yuca (Manihot esculenta). Se compararon seis tratamientos: T0 (P. maximum), T1 (Leucaena leucocephala), T2 (Moringa oleifera), T3 (Tithonia diversifolia), T4 (Guazuma ulmifolia) y T5 (Hibiscus rosa-sinensis). Se determinó la composición química, fermentación y digestibilidad in vitro, así como la producción de ácidos grasos volátiles (AGV). Los datos se analizaron con un análisis de varianza. La proteína cruda fluctuó de 8.34% a 11.70%, y la fermentación y la digestibilidad de la materia seca aumentaron (hasta 38.23% y 18.23%, respectivamente) (p < 0.05) con T5, T2, T1 y T3. Además, T5 y T2 incrementaron (p < 0.001) el ácido propiónico, mientras que T1 y T3 incrementaron el ácido butírico. Se concluye que la adición de H. rosa-sinensis, M. oleífera, L. leucocephala y T. diversifolia mejoran el perfil de AGV, fermentación y digestibilidad de la dieta.

Abstract The aim of this study was to evaluate the nutritional value of Panicum maximum diets supplemented with 30% tree foliage mixed with cassava (Manihot esculenta). Six treatments were compared: T0 (P. maximum), T1 (Leucaena leucocephala), T2 (Moringa oleifera), T3 (Tithonia diversifolia), T4 (Guazuma ulmifolia) y T5 (Hibiscus rosa-sinensis). Chemical composition, in vitro fermentation and digestibility, and volatile fatty acids (VFA) production were determined. The data was analyzed with an analysis of variance. Crude protein fluctuated from 8.34% to 11.70%, and fermentation and dry matter digestibility increased (up to 38.23% and 18.23%, respectively) (p < 0.05) with T5, T2, T1, and T3. Furthermore, T5 and T2 increased (p < 0.001) propionic acid, and T1 and T3 increased butyric acid. It is concluded that the addition of H. rosa-sinensis, M. oleifera, L. leucocephala, and T. diversifolia improve the VFA profile, fermentation, and digestibility of the diet.

Resumen La producción de forrajes en el Cerrado presenta estacionalidad debido a estaciones bien definidas, una lluviosa, con altas temperaturas y días largos, y la otra, estación seca, con temperaturas más bajas y días más cortos. Con el fin de definir estrategias para mini mizar la estacionalidad en la producción de forrajes, se evaluaron las respuestas de crec imiento y acumulación de biomasa en cinco forrajes regados durante el invierno en Cerrado Goiano. El diseño experimental utilizado fue en bloques al azar, en un arreglo de parcelas divididas, con cinco repeticiones, cinco forrajes en las parcelas (tres del género Panicum maximum - mombaça, tanzânia y massai; dos del género Brachiaria brizantha - piatã y MG5) y cinco cortes en las subparcelas. Los cortes se realizaron entre julio y octubre de 2016. Los forrajes se cultivaron en un área irrigada con pivote y la lámina de agua se definió según la evapotranspiración de referencia (ETo), estimada por el tanque clase A, 0.8 kc y riego con un intervalo de dos días. Se evaluó el número de macollos, hojas por labranza, hojas por planta, biomasa de hojas y tallos frescos, biomasa seca de hojas y tallos, relación masa de hojas frescas x masa fresca, relación masa de hojas secas x masa seca de los cinco cortes. Los forrajes regados durante el invierno en el Cerrado Goiano mostraron un crecimiento satis factorio, alcanzando altura de planta con intervalos de corte más cortos que los encontrados en la literatura. Mombaça se destacó entre el Panicum y MG fue superior al piatã.

Abstract Forage production in the Cerrado is based on well-defined seasons: a rainy summer, and a dry winter. To define strategies that minimize the seasonality of forage production, responses in growth and biomass accumulation of five irrigated forages were evaluated during winter. The experimental design was randomized blocks, in a split plot arrangement, with five replicates, five forages in the plots (three of Panicum maximum - Mombasa, Tanzania, and Masai; two of Brachiaria brizantha - piatã and MG5), and five cuts in the subplots made from July to October 2016. Forages were cultivated with centre-pivot irrigation and the water level was defined according to the reference evapotranspiration determined through a Class A pan evaporation method, 0.8 kc, and two-day irrigation shifts. The number of shoots, leaves/tiller, leaves/plant, fresh leaf and stem biomass, dry leaf and stem biomass, fresh leaf mass/fresh stem mass ratio, dry leaf mass/dry stem mass ratio, and biomass accumulated in the five cuts were calculated. Irrigated forage during winter in the Goiás’ Cerrado showed satisfactory growth, reaching a lower plant height between cuts than those reported in the literature. Among the Panicum grasses, Mombasa grass stood out, and MG was superior to piatã grass.

Abstract This study was carried out to evaluate the time for the establishment of tropical forage grasses in the “Cerrado” biome, based on morphogenetic and structural traits. Three Brachiaria brizantha (Syn. Urochloa brizantha) cultivars (Paiaguás, Ipyporã and Marandu) and two Panicum maximum (Syn. Megathyrsus maximus) cultivars (Quênia and Tamani) were distributed in a randomized-block design with four replicates. Morphogenetic and structural traits of the pasture were assessed from d 35 to d 65 after sowing, at seven-day interval. Canopy height rose linearly with the establishment period, in all cultivars. In the Megathyrsus cultivars, tiller density decreased as the experimental period progressed, whereas the number of tillers in the Urochloa cultivars increased. The cultivars Ipyporã and Marandu had the highest leaf appearance rates. The lowest leaf elongation rates occurred in the cultivars Paiaguás, Ipyporã and Tamani, and the highest elongation rates in cv. Quênia. As a result, cv. Quênia showed the highest values of final leaf length (64.9 cm) and leaf blade mass (3,352.9 kg DM ha-1). The higher senescence rate of cv. Tamani (2.1 cm tiller-1 d-1) resulted in the highest percentage of dead material (1,815.5 kg ha-1) being found in the herbage mass of this cultivar. Cultivars Paiaguás, Marandu and Tamani were established at 44 d, whereas cv. Quênia and Ipyporã were established at 51 and 58 d after sowing, respectively, in the Brazilian Cerrado.

Resumen Este estudio se llevó a cabo para evaluar el tiempo para el establecimiento de gramíneas forrajeras tropicales en el bioma del “Cerrado”, con base en rasgos morfogenéticos y estructurales. Se distribuyeron tres cultivares (Paiaguás, Ipyporã y Marandu) de Brachiaria brizantha (Sin. Urochloa brizantha) y dos cultivares (Quênia y Tamani) de Panicum maximum (Sin. Megathyrsus maximus) en un diseño de bloques al azar con cuatro repeticiones. Los rasgos morfogenéticos y estructurales del pasto se evaluaron desde el día 35 hasta el día 65 después de la siembra, a intervalos de siete días. La altura del dosel aumentó linealmente con el período de establecimiento, en todos los cultivares. En los cultivares de Megathyrsus, la densidad de macollos disminuyó a medida que avanzaba el período experimental, mientras que el número de macollos en los cultivares de Urochloa aumentó. Los cultivares Ipyporã y Marandu tuvieron las tasas más altas de aparición foliar. Las tasas de elongación foliar más bajas se presentaron en los cultivares Paiaguás, Ipyporã y Tamani, y las tasas de elongación más altas en el cv. Quênia. Como resultado, el cv. Quênia mostró los valores más altos de longitud foliar final (64.9 cm) y masa de lámina foliar (3,352.9 kg MS ha-1). La mayor tasa de senescencia del cv. Tamani (2.1 cm macollo-1 d-1) dio como resultado que el mayor porcentaje de material muerto (1,815.5 kg ha-1) se encontrara en la masa de forraje de este cultivar. Los cultivares Paiaguás, Marandu y Tamani se establecieron a los 44 d, mientras que los cv. Quênia e Ipyporã se establecieron a los 51 y 58 días después de la siembra, respectivamente, en el Cerrado brasileño.

Resumen Introducción. El óxido nitroso es un gas de efecto invernadero de gran impacto sobre el calentamiento global. En los sistemas de producción ganaderos es de gran importancia buscar alternativas que permitan mitigar las emisiones de N2O, dentro de las cuales se ha considerado el uso de coberturas vegetales capaces de reducir el proceso de nitrificación. Objetivo. Evaluar la dinámica de los flujos de N2O en suelos bajo ocupación ganadera cubiertos con gramíneas mejoradas y fertilización nitrogenada (Úrea). Materiales y métodos. Esta investigación se desarrolló en un sistema de producción de carne en el valle medio del Rio Sinú, en el cual los flujos de N2O fueron monitoreados durante un periodo de 12 meses (noviembre 2014 - 2015). Se utilizó un diseño experimental de bloques completos al azar, en arreglo de parcelas divididas y 2 repeticiones, en donde la parcela principal correspondió a las gramíneas (Brachiariahumidicola CIAT679 y Panicummaximumcv. Tanzania) y suelo descubierto, y las subparcelas a 3 dosis de fertilización nitrogenada (0, 150, 300 kg.ha-1.año-1 N). Resultados. Los flujos de N2O fluctuaron según el contenido de humedad del suelo, asociado a los periodos de mayor o menor precipitación en la región. La cobertura con la gramínea Brachiariahumidicolacv CIAT679 mostró menores emisiones de N2O, mientras que las dosis de fertilizantes nitrogenados aumentaron las emisiones de N2O. Dichos efectos fueron en parte atenuados por el uso de la cobertura con Brachiariahumidicola CIAT679. Conclusiones. Los resultados obtenidos indican que las emisiones de óxido nitroso en los sistemas ganaderos podrían variar a partir del tipo de cobertura y las dosis de fertilización nitrogenada utilizadas. En este caso, se encontró que la cobertura con Brachiariahumidicolacv CIAT679 en los sistemas de producción ganaderos reduce en más del 40% las emisiones de óxido nitroso hasta una dosis de N máxima de 300 kg.ha-1.año-1.

Abstract Introduction. Nitrous oxide is a highly relevant greenhouse gas. In livestock production systems, it is of a great importance to search for alternatives to mitigate N2O emissions, among which the use of plant covers capable of reducing nitrification process has been considered. Objective. Evaluate the dynamics of N2O fluxes in livestock soils covered with two improved grasses and doses of nitrogen fertilization (Úrea). Materials and methods. This research was developed in a livestock system in the middle valley of the Rio Sinú, in which N2O fluxes were monitored during a period of 12 months (November 2014 - 2015). An experimental design of randomized complete block design was used, in an arrangement of divided plots and 2 repetitions, where main plot corresponded to grasses (Brachiariahumidicola CIAT679 and Panicum maximum cv. Tanzania) and bare soil; and the subplots fertilization dose of N (0, 150, 300 kg.ha-1.year-1 N). Results. The N2O fluxes fluctuated according to the soil moisture content, associated with periods of great or less precipitation in the region. Coverage with the grass Brachiariahumidicola cv CIAT679 showed lower N2O emissions, while the doses of nitrogen fertilizers increased N2O emissions. These effects were partially attenuated by the use of the coverage with BrachiariahumidicolaCIAT679. Conclusions. The results obtained indicate that nitrous oxide emissions in livestock systems could vary from the type of coverage and the doses of nitrogen fertilizer used. In our case, it was found that coverage with BrachiariahumdicolaCIAT769 in livestock production systems reduces nitrous oxide emissions by more than 40% with maximum N soil application of 300 kg.ha-1.year-1.

ABSTRACT. The present study aimed to evaluate the residual effects of the application of biofertilizer and mineral fertilizer on sward structure and morphological components of Panicum maximum cv. Massai. The experimental design comprised randomized blocks with six treatments consisting of increasing doses of swine biofertilizer (0, 10, 20, 30 and 40 Mg ha-1) and mineral fertilization (150 kg N ha-1, 33 kg P ha-1), with four replicates. The variables analyzed were pasture height, light interception, leaf area index, forage mass and morphological components. Plant height responded linearly and positively to biofertilizer levels in the three evaluations. The highest averages for light interception (51.63%) and leaf area index (1.64) were observed for the 240 days (40 Mg ha-1). Dry leaf mass was influenced by the increase in biofertilizer dose, with increments of 39.68%, 25.07% and 44.66% for the 240, 300 and 360 days, respectively, when compared to the control treatment. Mineral fertilization promoted lower mass of dead material and lower leaf area index but did not differ from biofertilizer for the other variables. The residual effect of swine biofertilizer was greater than that of mineral fertilization, with a minimum use of 20 Mg ha-1 a practical agronomic recommendation.

ABSTRACT This study examined the replacement of maize and soybean meal with cassava chips and alfalfa grazing, respectively. Twelve lactating Anglo-Nubian goats were kept on a Panicum maximum cv. Tobiatã pasture. The experiment was laid out in a Latin square design in which the following diets were tested: ground maize + soybean meal, cassava chips + soybean meal, ground maize + alfalfa grazing, and cassava chips + alfalfa grazing. The evaluated variables were feed intake, daily weight gain, milk yield and composition, and feeding behavior of the goats as well as production costs. Cassava chips and grazed alfalfa influenced the intakes of dry matter, crude protein, neutral detergent fiber, and total digestible nutrients. However, milk yield, body weight, and body score did not change. There was no diet effect on the proportions of protein, solids-not-fat, somatic cell count, or urea nitrogen in the milk. Treatments influenced the levels of fat, lactose, and total solids in milk, with the highest fat levels achieved with diets containing alfalfa. Grazing, rumination, and idle times and time spent interacting with other goats were not influenced by diets. The evaluated feedstuffs improved feed efficiency and reduced production costs. Therefore, cassava chips and alfalfa can replace certain ingredients without impairing the production performance of goats, but rather improving the profit of the producer.