RESUMO: Este estudo teve como objetivo avaliar o impacto da silagem de ração total de Megathyrsus maximus colhido com 70 cm de altura e concentrado no momento da silagem ou ração total de capim cortado a 70 cm, composta por Megathyrsus maximus colhido com 70 cm de altura (nos Exp. I e III) e silagem de ração total cortada a 130 cm, composta por Megathyrsus maximus colhido com 130 cm de altura e concentrado no momento da silagem ou ração total de Megathyrsus maximus colhido a 130 cm de altura (nos Exp. II e IV), sobre o metabolismo ruminal, a digestibilidade dos nutrientes, e o desempenho e as características de carcaça de cordeiros confinados. Os resultados mostraram que TMRS70 aumentou o pH ruminal no Exp. I, e TMRS130 exibiu maior digestibilidade do extrato etéreo, concentração de propionato e menor razão acético/propionato e pH ruminal em comparação com TMR130 no Exp. II. Nos Exp. III e IV, não houve efeito significativo sobre o desempenho e a qualidade da carcaça. No entanto, no Exp. IV, TMRS130 levou a uma diminuição no consumo de matéria seca e no ganho médio diário, enquanto cordeiros alimentados com TMR130 mostraram uma maior área de olho de lombo. A ensilagem da ração total poderia ser usada como um método de conservação para gramíneas jovens (70 cm) sem prejudicar o desempenho, metabolismo, carcaças e qualidade da carne. No entanto, recomenda-se mais estudos avaliando a análise econômica da alimentação com ensilagem de ração total (70 cm) em vez de ração totalmente misturada como método de conservação de forragem. RESUMO 7 nos Exp 13 IV , IV) nutrientes confinados TMRS TMRS7 TMRS13 etéreo acéticopropionato acético TMR TMR13 entanto diário lombo (7 carne recomendase recomenda se forragem 1 TMRS1 TMR1 (

ABSTRACT: This study assessed the impact of total mixed ration silage of Megathyrsus maximus harvested with 70 cm composed of Megathyrsus maximus harvested at 70 cm in height and concentrate at the time of silage or total mixed ration of grass cut at 70 cm composed of Megathyrsus maximus harvested with 70 cm in height (in Exp. I and III) and total mixed ration silage cut at 130 cm composed of Megathyrsus maximus harvested 130 cm height and concentrate at the time of silage or total mixed ration of Megathyrsus maximus harvested with 130 cm composed of Megathyrsus maximus harvested at 130 cm height (in Exp. II and IV), on rumen metabolism, nutrient digestibility, and the performance and carcass characteristics of feedlot lambs. The results showed that TMRS70 increased ruminal pH in Exp. I and TMRS130 exhibited higher ether extract digestibility, propionic concentration, and lower acetic to propionic ratio and ruminal pH compared to TMR130 in Exp. II. In Exp. III and IV, there was no significant effect on the performance and quality of the carcass. However, in Exp. IV, TMRS130 led to decreased dry matter intake and average daily gain, while lambs fed with TMR130 showed a higher rib-eye area. Total ration ensilage could be used as a conservation method for young grasses (70 cm) without impairing performance, metabolism, carcasses, and meat quality. However, further research is recommended to evaluate the economic analysis of feeding total ration ensilage (70 cm) instead of total mixed ration as a forage conservation method. ABSTRACT 7 Exp 13 IV , IV) metabolism digestibility TMRS TMRS7 TMRS13 concentration TMR TMR13 However gain ribeye rib eye area (7 carcasses 1 TMRS1 TMR1 (

Resumen El sistema de producción bovino de doble propósito es el más predominante en el trópico, caracterizado por un sistema de pastoreo extensivo de gramíneas nativas o introducidas con baja digestibilidad y altas concentraciones de carbohidratos estructurales, provocando con esto una baja eficiencia productiva de los sistemas, ante este escenario, es necesario buscar alternativas que mejoren la eficiencia productiva. El objetivo fue evaluar la fermentación anaeróbica y digestibilidad ruminal in vitro de la materia seca (DIVMS) de los ensilados de S. bicolor y C. cajan. En los tratamientos se utilizaron cuatro sustratos (sorgo, sorgo + C. cajan, C. cajan, sorgo + C. cajan + inoculante) y cuatro tiempos de fermentación anaeróbica (0, 30, 60 y 90 días), en un diseño completamente al azar con un arreglo factorial 4x4, con tres repeticiones. El promedio de MS, MO, PC, FDN y FDA fue 373.9±41.43; 960.58±7.59; 87.82±24.95; 588.73±51.17; 371.76±61.39 g kg-1 de MS. Para la DIVMS fue de 56.32±9.05%. Se encontró diferencias significativas (P<0.05) para los parámetros de fermentación y DIVMS. El volumen máximo de gas se presentó en los tratamientos que contenían únicamente sorgo y sorgo + C. cajan + inoculante. Las fracciones de rápida fermentación fueron mayores (P<0.05) en los tratamientos sorgo + C. cajan + inoculante. Las fracciones de fermentación media y lenta fueron mayores en sorgo y sorgo + C. cajan + inoculante. Se concluye que la planta de C. cajan sola o combinada presenta un efecto negativo en la DIVMS.

ABSTRACT The dual-purpose cattle production system is the most predominant in the tropics, characterized by an extensive grazing system of native or introduced grasses with low digestibility and high concentrations of structural carbohydrates, causing with this a low productive efficiency of the systems, in this scenario, it is necessary to look for alternatives that improve productive efficiency. The objective was to evaluate the anaerobic fermentation and rumen digestibility in vitro of dry matter (DIVDM) of silages of S. bicolor and C. cajan. Four substrates (sorghum, sorghum + C. cajan, sorghum + C. cajan + inoculant) and four anaerobic fermentation times (0, 30, 60 and 90 days) were used in the treatments, in a completely randomized design with a 4x4 factorial arrangement, with three replications. The average for DM, OM, CP, NDF and ADF was 373.9±41.43; 960.58±7.59; 87.82±24.95; 588.73±51.17; 371.76±61.39 g kg-1 DM. For DIVDM it was 56.32±9.05 %. Significant differences (P<0.05) were found for fermentation parameters and DIVDM. The maximum volume of gas was presented in treatments containing only sorghum and sorghum + C. cajan + inoculant. The fractions of rapid fermentation were higher (P<0.05) in the treatments sorghum + C. cajan + inoculant. The fractions of medium and slow fermentation were higher in sorghum and sorghum + C. cajan + inoculant. It is concluded that the C. cajan plant alone or combined has a negative effect on DIVDM.

Abstract The objective of this work was to determine the effect of solar radiation intensity of the grazing system on sheep behavior. Treatment 1, consisted of monoculture of natural grasses (47 ± 5 lux), treatment 2 of natural grasses with Leucaena leucocephala trees (34 ± 3 lux) and treatment 3 of natural grasses with Manguifera indica trees (16 ± 3 lux). The total time of each activity per daily session was determined. A completely randomized design was used with a 3x2 factorial arrangement (three intensities of solar radiation, two sessions per day). Grazing behavior was affected by the interaction between factors. The grazing-walking activity was higher in the pastures with lower levels of solar radiation (Leucaena y Manguifera), with 217.50 y 216.38 min, respectively, in the morning session, while all times were lower in the afternoon session, with the lowest result in grazing in the sun (108.05 minutes). The reduction of solar radiation under the treetops favored the behavior of the sheep, which allowed the animals to perform resting and ruminating activities under the shade of the trees, more preferably in the afternoon session.

Resumen El objetivo fue determinar el efecto de la intensidad de radiación solar del sistema de pastoreo en la conducta de ovinos. El tratamiento 1 consistió en: monocultivo de gramíneas naturales (47 ± 5 lux); el 2: gramíneas naturales con árboles de Leucaena leucocephala (34 ± 3 lux); y el 3: gramíneas naturales con árboles de Manguifera indica (16 ± 3 lux). Se determinó el tiempo total de cada actividad por sesión del día. Se utilizó un diseño completamente aleatorizado, con arreglo factorial 3x2 (tres intensidades de radiación solar por dos sesiones del día). La conducta en pastoreo fue afectada por la interacción entre los factores. La actividad pastar-caminar fue mayor en los pastoreos de menor nivel de radiación solar (Leucaena y Manguifera) con 217.50 y 216.38 min respectivamente, en la sesión de la mañana; mientras que todos los tiempos fueron menores en la sesión tarde, con el menor resultado en el pastoreo al sol (108.05 minutos). La reducción de la radiación solar bajo la copa de los árboles favoreció el comportamiento conductual de las ovejas, esto permitió que los animales realizaran actividades de descanso y rumia bajo la sombra de los árboles, con más preferencia en la sesión tarde.

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. Blissus Hemiptera (Hemiptera Blissidae Blissidae) nutrients death Thus B speciescultivars species cultivars species/cultivars greenhouse nochoice no ruziziensis U humidicola ‘Piatã, Piatã ‘Piatã , ‘Piatã’ ‘Paiaguás, Paiaguás ‘Paiaguás ‘Paiaguás’ ‘Marandu, Marandu ‘Marandu ‘Mombaça, Mombaça ‘Mombaça P ‘Zuri, Zuri ‘Zuri bug s infestation A insects nonpreference non preference (antixenosis sheaths

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. percevejosdasgramíneas percevejos Blissus Hemiptera (Hemiptera Blissidae Blissidae) nutrientes morte Assim B espéciescultivares cultivares vegetação utilizandose utilizando se ruziziensis U humidicola ‘Piatã, Piatã ‘Piatã , ‘Piatã’ ‘Paiaguás, Paiaguás ‘Paiaguás ‘Paiaguás’ ‘Marandu, Marandu ‘Marandu ‘Mombaça, Mombaça ‘Mombaça P ‘Zuri, Zuri ‘Zuri infestação insetos Concluise Conclui nãopreferência não preferência

ABSTRACT Dry direct-seeding can get rid of the constraints of high-water demand, and is the simplest and most labor-saving mode in rice (Oryza sativa L.) cultivation. However, weeds are more prone to occur in dry direct-seeding rice fields, coupled with increased herbicide resistance, leading to confusion among growers regarding herbicide selection. In this study, our investigation results revealed total grass quantity reached 458.82 plants m-2. Two round of field experiments were conducted to determine suitable post-emergence herbicides for dry direct-seeding indica rice. The results showed that among the herbicides safe to indica rice, the efficacy of the combination of pyraquinate (a new 4-hydroxyphenylpyruvate dioxygenase inhibitor, 150.0 g ai ha-1) + florpyrauxifen-benzyl (13.5 g ai ha-1) on Leptochloa chinensis (L.) Nees, Eclipta prostrata (L.) L., Cyperus iria L., Fimbristylis miliacea auct., and total grasses were 89.1%, 97.8%, 97.2%, 90.1%, and 92.8%, respectively; the efficacy of metamifop (120.0 g ai ha-1) + florpyrauxifen-benzyl (18.0 g ai ha-1) and 22.0% cyhalofop-butyl + pyrazosulfuron-ethyl + bispyribac-sodium OD (148.5 g ai ha-1) on main weeds also exceeds 85.0%, except for cyhalofop-butyl-resistant L. chinensis. The combination of metamifop + florpyrauxifen-benzyl and 22.0% cyhalofop-butyl + pyrazosulfuron-ethyl + bispyribac-sodium OD can be selected for fields where L. chinensis is not resistant to acetyl-CoA carboxylase (ACCase) inhibitors. The combination of pyraquinate + florpyrauxifen-benzyl is the most promising combination to control multiple weeds, even ACCase inhibitors-resistant weeds. This study could also provide references for herbicides selection and management of ACCase inhibitors-resistant L. chinensis in dry direct-seeding indica rice field worldwide.

Abstract The use of chemical inputs has led to the loss of microbial diversity involved in the N cycle, such as diazotrophic bacteria, which are inhibited by saturation of the receptors responsible for activating nitrogenase. Biological nitrogen fixation (BNF) in forage grasses can be used as an ecosystem service. The aim of this review was to analyze the contribution of forage grasses to BNF and their response to inoculation of non-symbiotic diazotrophs in order to find study opportunities. The analysis of the information was carried out using the prisma methodology of systematic reviews and meta-analyses. It should be noted that the main forage species that contribute to BNF are Brachiaria sp. and Pennisetum sp. The inoculation of Azospirillum sp. has generated a growth-promoting effect in grasses, but the response of the inoculated forage depends mainly on the synergy between plant and bacteria, showing neutral, antagonistic, and positive effects.

Resumen El uso de insumos de origen químico ha generado pérdida de la diversidad microbiana que interviene en el ciclo del N como bacterias diazótrofas, que son inhibidas por saturación de los receptores encargados de activar la nitrogenasa. La fijación biológica de nitrógeno (FBN) en gramíneas forrajeras puede ser utilizada como servicio ecosistémico. El objetivo de este artículo de revisión fue analizar la contribución de gramíneas forrajeras a la FBN y su respuesta a la inoculación de diazótrofas no simbióticas para encontrar oportunidades de estudio. El análisis de la información se realizó a partir de la metodología prisma de revisiones sistemáticas y meta-análisis. Se destaca que las principales especies forrajeras que contribuyen con la FBN corresponden a Brachiaria sp. y Pennisetum sp. La inoculación de Azospirillum sp. ha generado efecto promotor de crecimiento en gramíneas, pero, la respuesta del forraje inoculado depende principalmente de la sinergia entre planta - bacteria presentándose efectos neutros, antagónicos y positivos.

Abstract Pastures is important for livestock production, are source of food mainly for ruminant livestock. The study was conducted in grasslands of the highlands of Puno, Peru, at an altitude of 3818 masl. The objective was to determine the effect of revegetation with two native grasses: Festuca dolichophylla Presl "chilligua" (Fedo) and Poa gilgiana Pilger "K'achu" (Pogi) in the recovery of degraded pastures with the addition of sheep manure as a source of organic matter (OM), conducted under a split-plot design whose study factors were 2 native species, 2 fertilization factors with and without the addition of sheep feces and urine (OM), in 3 blocks; The results indicate that the highest growth and biomass yield was for Fedo, probably due to its adaptive capacity, the green matter yield of Fedo and Pogi was higher in the treatment with the addition of OM, the incorporation of manure to the pasture had a positive influence on the recovery of the pasture, on the other hand Fedo had a greater height than Pogi; Likewise, the seed production of the treatments with added OM was higher than the treatments without OM; the protein content with addition of OM was higher in both species and the NDF was higher in the species without addition of OM; the application of OM favored the growth and nutritive value of the species. It was concluded that revegetation and incorporation of sheep manure had a favorable effect on the recovery and nutritional quality of the pasture.

Resumen Los pastizales naturales son importantes para la producción ganadera, son fuente de alimentación principalmente para el ganado rumiante. El estudio se realizó en pajonales del altiplano de Puno Perú a una altitud de 3818 msnm el objetivo fue determinar el efecto de la revegetación con dos gramíneas nativas: Festuca dolichophylla Presl “chilligua” (Fedo) y Poa gilgiana Pilger “K´achu” (Pogi) en la recuperación de pastizales degradados con adición de estiércol de ovino como fuente de materia orgánica (MO), conducido bajo el diseño de parcelas divididas cuyos factores de estudio fueron 2 especies nativas, 2 factores de abonamiento con y sin adición de (MO) heces y orina de ovino, en 3 bloques; los resultados indican que el mayor crecimiento y rendimiento de biomasa fue para Fedo probablemente por su capacidad de adaptación, rendimiento de materia verde de Fedo y Pogi fue superior en el tratamiento con adición de MO, la incorporación de estiércol al pastizal influyo positivamente en la recuperación del pasto, por otra parte Fedo resulto con mayor altura que Pogi;; la producción de semilla de los tratamientos adicionados con MO fueron superiores a los tratamientos sin aporte de MO; el contenido de proteína con adición de MO fue mayor en ambas especies, la FDN fue mayor en las especies sin adición de MO, la aplicación de MO favoreció el crecimiento y el valor nutritivo de las especies. Se concluye que la revegetación e incorporación de estiércol de ovino tuvo un efecto favorable en la recuperación y calidad nutritiva del pastizal.

ABSTRACT Understanding the dietary needs is important for the conservation of the bighorn sheep. The objective was to identify the diet selection in Coahuila, Mexico. The research was conducted at the Rancho San Juan Wildlife Management Unit (UMA), Monclova municipality, from August 2018 to October 2019. Forage availability was assessed using 18 Canfield transects. Diet composition was estimated through microhistology on 280 fecal samples, and diet and forage diversity were assessed using the Shannon index. Cluster and principal component analyses (PCA) were applied to analyze similarity in consumption across different species and seasonal influences. Shrubs were the most available (48%). A total of 50 species and 14 families were identified in the diet, with shrubs (49.2%) and grasses (17.21%) being predominant. Tiquilia canescens, Gymnosperma glutinosum, Opuntia rufida, Medicago sativa, and Erioneuron pulchellum were the most consumed species. The bighorn sheep consumed tree and shrub species proportionally (1.1 and 1.02, respectively), preferred herbaceous plants in spring (2.24) and autumn (15.28), and grasses in spring (6.10), except in summer (0.83) when they avoided succulents. PCA revealed that the first two components explained 96.05% of the correlation between species consumption frequencies and their biological forms. Cluster analysis grouped five forage consumption categories. Conserving shrub species, which form the basis of the bighorn sheep's diet, grasses-its preference-and succulents as buffering elements, is essential.

RESUMEN Comprender las preferencias alimentarias es importante para la conservación del borrego cimarrón. El objetivo fue identificar la selección de su dieta en Coahuila, México. La investigación se realizó en la UMA Rancho San Juan, municipio de Monclova, de agosto 2018 a octubre 2019. La disponibilidad de forraje se evaluó con 18 líneas de Canfield. La composición de la dieta se estimó con microhistología en 280 muestras fecales, y la diversidad de la dieta y del forraje con el índice de Shannon. Para analizar la similitud en el consumo de diferentes especies y la influencia estacional, se aplicaron análisis de clústers y componentes principales (ACP). Las arbustivas estuvieron más disponibles (48%). Se identificaron 50 especies y 14 familias en la dieta, y predominaron las arbustivas (49.2%) y los pastos (17.21%). Tiquilia canescens, Gymnosperma glutinosum, Opuntia rufida, Medicago sativa y Erioneuron pulchellum fueron las más consumidas. El borrego consumió especies arbóreas y arbustivas de manera proporcional (1.1 y 1.02, respectivamente), prefirió las herbáceas en primavera (2.24) y otoño (15.28), los pastos en primavera (6.10), y con excepción de verano (0.83), evitó las suculentas. El ACP reveló que los dos primeros componentes explican el 96.05% de la correlación entre las frecuencias de consumo de las especies y sus formas biológicas. El análisis de clústers agrupó cinco categorías de consumo de forraje. Es fundamental conservar las arbustivas, que constituyen la base de la dieta del borrego cimarrón, los pastos, que son sus preferidos, y las suculentas, como elementos amortiguadores.

Abstract Pastures that include annual and perennial grasses can play a strategic role in increasing the sustainability of temperate livestock systems. However, the impacts of the competition between annual and perennial genetically improved forage species on pastures has scarcely been studied. We evaluated the early dynamics of tillering, carbon partitioning and both intra- and interspecific competition in – or between – an annual (Bromus willdenowii; prairie grass; Bw) and a perennial (Dactylis glomerata; orchard grass; Dg) C3 grass species. We sowed 24 0.18 m2 microplots in May 2008. Each microplot constituted an experimental unit and contained five sowing lines spaced 0.175 m apart. On three of the lines, we sowed different combinations of the mentioned grasses, while on the two lines between them, we sowed red clover (Trifolium pratense). We randomly applied a factorial array of eight treatments—2 species (Dg vs. Bw) × 2 types of competition (intra vs. interspecific) × 2 levels of winter nitrogen fertilization (0 vs. 170 kg of N ha-1)—designed in three complete random blocks. Fertilization did not have any significant effect on any species. The evaluation period lasted 109 days after sowing (das), separated into three phases (0-53 das, 59-90 das and 90-109 das). The variables recorded were aerial biomass (leaves, sheets and senescent material), root biomass and tiller density per species. As expected, annual Bw inhibited the growth of perennial Dg at the latest stage of establishment but surprisingly promoted it at the earliest stage. This work suggested that a low initial density of an annual species should optimize the initial facilitating effect of the annual species on the perennial species with its subsequent inhibitory effect.

Resumen Las gramíneas anuales y perennes pueden desempeñar un papel estratégico en el aumento de la sostenibilidad de los sistemas ganaderos de zonas templadas. Sin embargo, el impacto de la competencia entre especies forrajeras genéticamente mejoradas anuales y perennes en los pastos apenas ha sido estudiado. En este trabajo evaluamos la dinámica temprana del macollaje y la partición de carbono y la competencia intraespecífica e interespecífica en, o entre, una especie de pasto C3 anual (Bromus willdenowii; pasto de la pradera; Bw) y perenne (Dactylis glomerata; pasto de huerto; Dg). Sembramos 24 microparcelas de 0,18 m2 en mayo de 2008. Cada microparcela constituyó una unidad experimental y contenía cinco líneas de siembra espaciadas 0,175 m entre sí. En tres de las líneas sembramos diferentes combinaciones de las gramíneas mencionadas, mientras que en las dos líneas intermedias sembramos trébol rojo (Trifolium pratense). Aplicamos aleatoriamente un conjunto factorial de ocho tratamientos: 2 especies (Dg vs. Bw) × 2 tipos de competencia (intra vs. interespecífica) × 2 niveles de fertilización con nitrógeno invernal (0 vs. 170 kg de N ha-1), diseñado en tres bloques completos al azar. La fertilización no tuvo ningún efecto significativo en ninguna especie. El período de evaluación tuvo una duración de 109 días después de la siembra (dds), separados en tres fases (0-53 dds, 59-90 dds y 90-109 dds). Las variables registradas fueron biomasa aérea (hojas, láminas y material senescente), biomasa de raíces y densidad de macollos por especie. Como se esperaba, Bw inhibió el crecimiento de Dg en la última etapa de establecimiento, pero sorprendentemente lo promovió en la etapa más temprana. Este trabajo sugirió que una baja densidad inicial de una especie anual debería optimizar el efecto facilitador inicial de la especie anual sobre la especie perenne con su posterior efecto inhibidor.

Abstract The estimation of aerial biomass of grasses contributes to carrying out efficient and sustainable management of rangelands. This study aimed to generate new equations to estimate the aerial biomass of grasses present in rangelands in Nuevo León, Mexico, based on data collected from the total number (n= 745) of individuals of the five species of grasses: Cenchrus ciliaris Linnaeus, Pappophorum bicolor Fourn, Aristida purpurea Nutt, Tridens texanus Watson and Paspalum pubiflorum Fourn present in the sampling plots. Using the maximum height and the height of the vegetative stems, the aerial, basal, and compressed diameters, and volumes measured in each of the collected individuals, linear (stepwise) and nonlinear equations were generated to estimate the aerial biomass (dry matter basis) of the grasses cut at ground level. Six general equations with the best statistical fit for the total species collected were selected. General equation III had the best values of R2 =0.88 and AIC =3079, using the five variables evaluated. General equation IV had an R2 =0.86 and AIC =3530, using only the variable compressed diameter. The selected specific equations estimated the aerial biomass of the grasses Cenchrus ciliaris (R2=0.88, r=0.94), Pappophorum bicolor (R2 =0.86, r =0.92), Aristida purpurea (R2=0.92, r=0.96), Tridens texanus (R2 =0.91, r =0.96), and Paspalum pubiflorum (R2 =0.93, r = 0.97). The new equations are a reliable alternative to indirectly estimate the aerial biomass of the grasses of the rangelands of northeastern Mexico in a faster and less expensive manner than the traditional method.

Resumen La estimación de biomasa aérea de pastos contribuye a realizar un manejo eficiente y sostenible de los agostaderos. El objetivo del presente estudio fue generar nuevas ecuaciones para estimar la biomasa aérea de pastos presentes en agostaderos, en Nuevo León, México, basado en datos colectados del total (n=745) de los individuos de las cinco especies de pastos: Cenchrus ciliaris Linnaeus, Pappophorum bicolor Fourn, Aristida purpurea Nutt, Tridens texanus Watson y Paspalum pubiflorum Fourn presentes en las parcelas de muestreo. Utilizando la altura máxima y la de los tallos vegetativos, los diámetros aéreo, basal y comprimido, y volúmenes medidos en cada uno de los individuos colectados, se generaron ecuaciones lineales (stepwise) y no lineales, para estimar la biomasa aérea (base materia seca) de los pastos cortados a ras de suelo. Se seleccionaron seis ecuaciones generales con el mejor ajuste estadístico para el total de las especies colectadas. La ecuación general III tuvo los mejores valores de R2=0.88 y AIC=3079, utilizando las cinco variables evaluadas. La ecuación general IV estimó con R2=0.86 y AIC= 3530, utilizando solo la variable de diámetro comprimido. Las ecuaciones específicas seleccionadas estimaron la biomasa aérea de los pastos Cenchrus ciliaris (R2=0.88, r=0.94), Pappophorum bicolor (R2=0.86, r=0.92), Aristida purpurea (R2=0.92, r=0.96), Tridens texanus (R2=0.91, r=0.96), y Paspalum pubiflorum (R2=0.93, r=0.97). Las nuevas ecuaciones son una alternativa confiable para estimar indirectamente la biomasa aérea de los pastos de los agostaderos del noreste de México, de forma más rápida y menos costosa que el método tradicional.

Abstract This study aimed to evaluate whether bacterial inoculation improves the fermentative, microbiological, and chemical characteristics of silages of the elephant grass cv. BRS Capiaçu on different regrowth days. The experimental design was completely randomized and set up in a 3x2 factorial arrangement (three regrowth days, with and without inoculant), with four replications. There was a significant interaction between the regrowth days and inoculant on the pH, ammoniacal nitrogen (N-NH3), and effluent losses (EL) of the silages. Inoculation decreased the EL with the advance of regrowth days and increased the dry matter recovery index compared to the silages without inoculant. The population of molds and yeasts decreased when inoculation was adopted to the forage harvested after 85 d. There was a significant interaction between the dry matter (DM), crude protein (CP) and neutral detergent fiber corrected for ash and protein (NDFap) contents of the silages. Inoculation in the grass harvested after 85 d increased the DM contents of the silage. The highest CP contents were observed in the silages after 85 d. The NDFap contents of the grasses harvested after 110 and 135 d were higher than those of the grass harvested after 85 d. The NDFap contents of the silages without inoculant increased with the harvest age. The BRS Capiaçu forage silage harvested at 110 d demonstrated favorable performance for silage production. However, the influence of inoculant use was low for the characteristics evaluated.

Resumen Este estudio tuvo como objetivo evaluar si la inoculación bacteriana mejora las características fermentativas, microbiológicas y químicas de los ensilados del pasto elefante cv. BRS Capiaçu en diferentes días de rebrote. El diseño experimental fue completamente al azar y se estableció en un arreglo factorial 3x2 (tres días de rebrote, con y sin inoculante), con cuatro repeticiones. Hubo una interacción significativa entre los días de rebrote y el inoculante sobre el pH, el nitrógeno amoniacal (N-NH3) y las pérdidas por efluentes (PE) de los ensilados. La inoculación disminuyó la PE con el avance de los días de rebrote y aumentó la tasa de recuperación de materia seca en comparación con los ensilados sin inoculante. La población de mohos y levaduras disminuyó cuando se adoptó la inoculación al forraje cosechado después de 85 d. Hubo una interacción significativa entre la materia seca (MS), la proteína cruda (PC) y la fibra detergente neutro corregida por los contenidos de cenizas y proteína (FDNcp) de los ensilados. La inoculación en el pasto cosechado después de 85 días aumentó el contenido de MS del ensilado. Los mayores contenidos de PC se observaron en los ensilados después de 85 días. Los contenidos de FDNcp de los pastos cosechados después de 110 y 135 días fueron mayores que el del pasto cosechado después de 85 días. El contenido de FDNcp de los ensilados sin inoculante aumentó con la edad de cosecha. El ensilado de forraje de BRS Capiaçu cosechado a los 110 días demostró un desempeño favorable para la producción de ensilado. Sin embargo, la influencia del uso de inoculantes fue baja para las características evaluadas.

Abstract Background: Roadside plants grow along transportation routes, and are little studied. Questions: What is the richness of roadside angiosperms? What is the percentage of native and introduced species for roadside angiosperms? Species studied: Native and introduced roadside angiosperms. Site and years of study: Chalma-Malinalco roadside, municipality of Malinalco, State of Mexico, Mexico, May 2008-April 2009. Methods: Angiosperm species were collected along the road right-of-way during 24 biweekly walks. Additionally, species were listed and their cover estimated in 14 sampling sites (4 m2 each). Results: We recorded 327 species. Asteraceae, Fabaceae and Poaceae were the families with the highest richness of genera and species. Native species were dominant (85.9 %), whereas introduced species grouped 14.1 %; the latter came mainly from the Old World. About 70 % of the species were herbs. Bouteloua repens and Eleusine indica had the highest cover and frequency, respectively. Conclusions: The roadside flora was rich in angiosperms, mostly herbs, and with a dominance of native plants. Introduced grasses played an outstanding role in terms of frequency. It is necessary to continue with floristic, ecological and ethnobotanical research, among others, on this group of plants that has been scarcely studied.

Resumen Antecedentes: Las plantas viarias crecen en las orillas de vías de comunicación y han sido poco estudiadas. Preguntas: ¿Cuál es la riqueza de las angiospermas viarias? ¿Cuál es el porcentaje de especies nativas e introducidas entre las angiospermas viarias? Especies de estudio: Angiospermas viarias nativas e introducidas. Sitio y años de estudio: Carretera Chalma-Malinalco, municipio de Malinalco, Estado de México, México, mayo 2008-abril 2009. Métodos: Se recolectaron las especies de angiospermas en el derecho de vía de la carretera a través de 24 recorridos quincenales. Adicionalmente, se enlistaron las especies y se estimó su cobertura en 14 cuadros de muestreo (4 m2 cada uno). Resultados: Se registraron 327 especies. Asteraceae, Fabaceae y Poaceae fueron las familias con mayor riqueza de géneros y especies. Las especies nativas fueron dominantes (85.9 %), mientras que las introducidas agruparon el 14.1 %; éstas últimas procedieron principalmente del Viejo Mundo. Alrededor del 70 % de las especies fueron hierbas. Bouteloua repens y Eleusine indica presentaron mayor cobertura y frecuencia, respectivamente. Conclusiones: La flora viaria era rica en angiospermas, la mayoría hierbas y con dominancia de plantas nativas. Los pastos introducidos tenían un papel sobresaliente en cuanto a frecuencia. Es necesario continuar con investigaciones florísticas, ecológicas, etnobotánicas, entre otras, sobre este grupo de plantas que ha sido escasamente estudiado.

Abstract Digitaria sanguinalis and the species of the genus Setaria (S. adhaerens, S. verticillata and S. viridis) are among the most important grass weeds affecting maize cultivation in Spain. This study analyzed the response to the acetolactate synthase (ALS) inhibitor herbicide nicosulfuron of 23 D. sanguinalis populations and 20 Setaria spp. populations collected in a random survey conducted in maize fields in León, Salamanca, Zamora and Valladolid, the main growing areas of Castilla y León, in the year 2017. The plants were pre-germinated, transplanted and treated with nicosulfuron at a dose of 45 g. m.a. ha-1 at the 2-3 leaf stage. Four weeks after treatment the plants were evaluated and differentiated according to their phenotype in relation to an untreated control in: dead and/or severely damaged (susceptible), moderately damaged (intermediate resistance) and slightly damaged (resistant). Percentage of resistant plants was used to classify populations as susceptible, developing resistance or resistant. For Setaria spp. the plant mortality was 100% in all the populations. For D. sanguinalis, surviving plants were found in all populations with a mean frequency of 8.6 ± 6.9% (1.8-30.4%), with 96% of the populations developing resistance and one population (4%) from the province of León being classified as resistant. Data obtained will be useful to monitor the evolution of the resistance over time in the surveyed geographical regions.

Resumen Digitaria sanguinalis y las especies del género Setaria (S. adhaerens, S. verticillata y S. viridis) se encuentran entre las principales malas hierbas gramíneas que afectan al cultivo de maíz en España. En este estudio se analizó la respuesta al herbicida inhibidor de la acetolactato sintasa (ALS) nicosulfuron de 23 poblaciones de D. sanguinalis y 20 poblaciones de Setaria spp. procedentes de un muestro aleatorio llevado a cabo en 2017 en campos de maíz de León, Salamanca, Zamora y Valladolid, principales zonas de cultivo de Castilla y León. Las plantas se pregerminaron, trasplantaron y trataron con nicosulfuron a una dosis de 45 g. m.a. ha-1 en el estado de 2-3 hojas. Cuatro semanas después del tratamiento las plantas se evaluaron visualmente y se diferenciaron en función de su fenotipo en relación con un control no tratado en: muertas y/o gravemente dañadas (susceptibles), moderadamente dañadas (resistencia intermedia) y ligeramente dañadas (resistentes). Se utilizó el porcentaje de plantas resistentes para clasificar las poblaciones como susceptibles, desarrollando resistencia o resistentes. En el caso de las especies de Setaria spp. la mortalidad de las plantas fue del 100% en todas las poblaciones. En D. sanguinalis, se encontraron plantas supervivientes en todas las poblaciones con una frecuencia media del 8,6 ± 6,9% (1,8-30,4%), con el 96% de las poblaciones desarrollando resistencia y una población (4%) de la provincia de León clasificada como resistente. Estos datos serán útiles para realizar el seguimiento del desarrollo de la resistencia a este herbicida a lo largo del tiempo en las zonas geográficas muestreadas.

ABSTRACT The concentration of linoleic and α-linolenic fatty acids (FA) in grasses can be increased through agronomic techniques; however, there is little information in this regard for tropical grasses. Therefore, the objective of the study was to evaluate the effect of N fertilization and regrowth age management on the FA profile of three tropical grasses. To do this, three plots of 100 m2 each were used for the species: Urochloa decumbens (Stapf) R.D. Webster, U. humidicola (Rendle) Morrone & Zuloaga, and Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs. The study was conducted during dry and rainy seasons. In each period, they were divided into two subplots and only one of them was fertilized. Grass sampling was carried out on days 20, 25, and 30 after fertilization. Five samples were taken from each subplot and an agronomic evaluation was made before each cut. The chemical composition and lipid profile were then determined. An ANOVA of a randomized complete block design with split plot arrangement was performed. The concentration of linoleic and α-linolenic acid was higher in M. maximus during drought (48.5 g 100 g-1 FA) and in U. humidicola during the rainy season (55.1 g 100 g-1 FA). This proportion was higher on day 20 (50.5 g 100 g-1 FA) compared to that recorded on days 25 and 30 (50.1 and 45.7 g 100 g-1 FA, respectively). The fertilized grasses had a higher concentration of linoleic and α-linolenic acid compared to the unfertilized ones (53.4 vs. 44.3 g 100 g-1 FA). It is concluded that fertilization with 50-20-00 (N-P-K) increases the proportion of linoleic and α-linolenic acids in grasses; however, such concentration decreases with increasing plant maturity.

Resumo O foco atual está no padrão geral de armazenamento de sementes presente nos fragmentos de solo do Piemonte e nas paisagens aluviais do meio ambiente. O presente estudo previu os bancos de sementes de ambos os solos das zonas aluvial e piemontesa em diferentes condições ecológicas e avaliou o potencial das sementes na restauração de ambos os ambientes. A composição do banco de sementes do solo é afetada principalmente pelo ambiente aluvial e a estrutura da área desmatada mostra que mais espécies de gramíneas anuais em germinação e sementes cultiváveis apresentam o maior número total. As estruturas da vegetação existente têm um papel importante na diversidade dos reservatórios de sementes do solo, cuja composição correspondeu à abertura do local. Quando o banco de sementes do solo in situ é recrutado, o mesmo ajuda a restaurar apenas alguns componentes da comunidade de plantas em um ambiente aluvial. Em nossa pesquisa atual, foi confirmado que a riqueza de sementes era maior em número em altitudes mais baixas (aluviais) do que em altitudes elevadas (Piemonte). A riqueza de sementes mostrou uma correlação negativa significativa com ânions, cátions, enquanto significativamente positiva com a altitude, o que sugere que o padrão de riqueza do banco geral de sementes da área é influenciado por vários fatores ambientais.

Abstract The current focus is on the overall pattern of seed storage present in the fragments of the soil of piedmont and alluvial landscapes of the environment. The present study predicted the seed banks of both soils of alluvial and piedmont zones in different ecological conditions and evaluate the potential of seeds in the restoration of both environments. The composition of the seed bank of soil is mainly affected by the alluvial environment and the structure of cleared area shows that more species of germinating annual grasses and growable seeds with the higher total number. Extant vegetation structures have an important role in the diversity of soil seed reservoirs, whose composition corresponded with the openness of the site. When in situ soil seed bank is recruited, it helps to restore only some components of the plant community in an alluvial environment. In our current research, it was confirmed that seed richness was higher in number at lower elevation (alluvial) than that at high elevation (piedmont). Seed richness showed a significant negative correlation with anions, cations, while significantly positive with altitude that suggests the richness pattern of the overall seed bank of the area is influenced by various environmental factors.