Comportamiento productivo del pasto ovillo (Dactylis glomerata L.) en respuesta al pastoreo

The aim of this study was to determine the yield variation patterns in orchard grass (Dactylis glomerata L.) under grazing management. This study was performed in Montecillo, Texcoco state, Mexico from June 2005 to July 2006. Three grazing frequencies (21, 28 and 35 days) and two grazing intensities (5-7 and 9-11 cm residual sward high) were evaluated in a completely random block design with three replicates. The variables grass yield, seasonal distribution, growth rate, botanical and morphological composition and tiller population density were all evaluated. A 35 day-grazing frequency produced the highest yield (P<0.05). Independently of the grazing intensity and its frequency the seasonal yield was: 49.5, 31.6, 14.1 and 4.8% for spring, summer, winter and fall, respectively. The highest growth rate was registered during spring when grazing occurred every 35 days, and the lowest during autumn when grazing occurred every 28 days (P<0.01). During winter grazing only occurred every 21 days, and this may have led to 60% contribution to total yield by other species. Results also suggest that tiller density was not affected by grazing intensity and frequency on tiller population density.El objetivo del estudio fue determinar los patrones de variación en los componentes de la productividad forrajera del pasto ovillo (Dactylis glomerata L.) bajo pastoreo. En Montecillo, Texcoco, Estado de México, México, de junio 2005 a junio 2006, se estudió la combinación de tres frecuencias (21, 28 y 35 días) y dos intensidades (5-7 y 9-11 cm) en el forraje residual de pastoreo, en un diseño de bloques al azar con tres repeticiones. Se evaluó el rendimiento anual y la distribución estacional de forraje, tasa de crecimiento, composición botánica y morfológica y densidad de tallos. La frecuencia de pastoreo de 35 días superó a las de 21 y 28 (P<0,05) en el rendimiento anual, durante primavera y verano. Independientemente de la frecuencia e intensidad de pastoreo, el rendimiento estacional se distribuyó de la siguiente forma: 49,5, 31,6, 14,1 y 4,8% para primavera, verano, invierno y otoño, respectivamente. La mayor tasa de crecimiento se registró en primavera al pastorear cada 35 días y la menor en otoño al pastorear cada 28 días (P<0,01). Durante invierno se dio mayor presencia de otras especies, siendo el pastoreo cada veintiún días a una intensidad ligera el que originó un aporte al rendimiento de otras especies del 60%. No se presentaron efectos de intensidad ni de frecuencia de pastoreo en la densidad de tallos. El mayor rendimiento y tasa de crecimiento se obtuvieron al pastorear cada 35 días

Producción de forraje y composición morfológica del pasto mulato (Brachiaria híbrido 36061) sometido a diferentes regímenes de pastoreo

Three grazing frequencies (14, 21 and 28 d) and two grazing intensities (9-11 and 13-15 cm cutting height) were assessed in Mulato grass (Brachiaria hybrid 36061) in a completely randomized block design with a 3*2 factorial arrangement and three replicates. The following attributes were taken into account, herbage yield, growth rate (GR), botanic composition and leaf:stem ratio. No significant interaction (P>0.05) was found between frequency*intensity for herbage yield. Herbage yield distribution was 55, 28 and 17 % respectively for the rainy, north and dry seasons in 2007-2008, evaluation period. The highest annual herbage yield (12,310 kg DM ha-1) was recorded with 28 d grazing interval at 13-15 cm of grazing intensity. Herbage yield increased progressively when grazing frequency lengthened from 14 to 28 d (PEn Brachiaria híbrido se estudiaron tres frecuencias (14, 21 y 28 días) y dos intensidades de pastoreo (9-11 y 13-15 cm), distribuidos en un diseño de bloques al azar en arreglo factorial 3 x 2 con tres repeticiones. Se midió: acumulación de forraje, tasa de crecimiento (TC) composición botánica y relación hoja: tallo. No hubo efecto de int eracción (P>0.05) frecuencia x intensidad en la acumulación de forraje. La distribución del rendimiento fue de 55, 28 y 17 % durante las épocas de lluvias, nortes y seca, en el año 2007-2008, con la mayor acumulación anual (12,310 kg MS ha-1) al pastorear cada 28 días, con un incremento progresivo conforme aumentó el intervalo de pastoreo de 14 a 28 días (

Analysis of the growth of Chetumal grass established in a tropical climate

Objective: To evaluate the growth of Chetumal grass (Urochloa humidicola CIAT 679), in order to determine the optimal moment for the first harvest. Design/Methodology/Approach: A completely randomized experimental block design, with measurements repeated over time, and three repetitions was used. Morphological composition (MC), growth rate (GR), plant height (PH), intercepted radiation (IR), leaf:stem ratio (L:S), leaf:no-leaf ratio (L:NL), and aerial biomass (AB) —as well as leaf biomass (LB), stem biomass (SB), dead material (DM), net growth (NG), and total biomass (TB)— were evaluated every fifteen days, except for the two first samplings, which were carried out on a monthly basis. Data were analyzed using the GLM procedure of the SAS software and Tukey’s mean comparison test (α£0.05). Results: The morphological composition (MC) of the Chetumal grass was statistically different (p&lt;0.05), during the different growth ages. The maximum accumulation of total biomass (TB) (13,324 kg DM ha-1), leaf biomass (LB) (2,569 kg DM ha-1), and growth rate (GR) (99 kg DM ha-1 d-1) was reached at 135 DAS. On that day, the prairie reached a 68 cm plant height (PH) and 100% intercepted radiation (IR). The L:S ratio decreased from 1.62 to 0.31, while L:NL ratio changed from 1.62 to 0.22. Study Limitations/Implications: The Brachiaria humidicola cv. Chetumal grass reached its highest potential during the rainy season. Findings/Conclusions: The first cut of the Urochloa humidicola cv. Chetumal grass can be carried out at 135 DAS, when the highest accumulation of total biomass (TB), leaf biomass (LB), and growth rate (GR) is recorded

Goat production systems of the central highlands of Veracruz, Mexico

ABSTRACT The objective of this study was to characterize the goat production units of the central mountainous area of the state of Veracruz. A multiple case study was carried out considering socioeconomic aspects, type of forage, goat feeding, reproduction, improvement, and health. The results showed that goat farming and cheese production represent between 50 and 100% of the producers' income. The cultivated forages and the type of goat feed of the production units in the mountainous area are King grass CT-115, Maralfalfa, African Star, Alfalfa and Corn. Animal reproduction is carried out by controlled mating and births occur at the beginning and end of each year. The goat herds do not exceed 150 heads with a predominance of Saanen and Alpine breeds. The average daily production of milk ranges between 16-90 L and with a production of 2-3 L milk for animal/day. The activity is family-type and involves cultivation, animal management, milk production and the manufacturing of artisanal cheeses. Studies are required to confirm individual milk production.Objective: This study was to characterize the goat production units of the central mountain area of the state of Veracruz, Mexico. Disign/methodology/approach: A multiple case study was carried out taking into consideration socioeconomic aspects, type of forage, goat feeding, reproduction, improvement, and health. Results: The results showed that goat and cheese production account for 50-100% of the producers' income. The forages grown and the type of goat feed used in the production units of the mountain area are: King grass, CT-115, maralfalfa, giant star grass, alfalfa, and corn. Animal reproduction is carried out by controlled mating and births take place at the beginning and end of each year. Flocks do not exceed 150 heads; the predominant breeds are Saanen and Alpine. The average daily production of milk ranges from 16 to 90 L, with a production of 0.75-3 L milk animal-1 day-1. Study limitations/implications: None Findings/conclusions: The activity is family-based and involves cultivation, animal management, and milk and artisanal cheese production. Further studies are required to confirm individual milk production

Evaluación de la distancia entre plantas sobre el rendimiento y calidad de semilla de Brachiaria brizantha

The objective was evaluating the effect of plant spacing on seed yield and quality in Bracchiaria brizantha cv. Marandú. The experiment was carried out in rain fed conditions in 2007 at the Universidad de Papaloapan, Loma Bonita, Oaxaca, Mexico. Six plant distances (broadcast, 25*25 cm, 50*50 cm, 75*75 cm, 100*100 cm and 125*125 cm between rows and plants, respectively) were assessed. To that end, a completely randomized block design with four replicates was set. The following variables were analyzed: pure seed yield (PSY), pure germinable seed yield (GPSY), number of panicles per m-2, panicle length,seed harvested per panicle, 1,000 seed weight, spikelet abscission rate, seed purity and germination. PSY and GPSY showed differences among treatments (PEl objetivo fue evaluar el efecto de la distancia entre plantas en el rendimiento y calidad de semilla de Brachiaria brizantha cv. Marandu. El experimento se realizó en temporal durante 2007, en la Universidad del Papaloapan, Loma Bonita, Oaxaca. Se evaluaron seis distancias entre plantas (voleo, 25 x 25, 50 x 50, 75 x 75, 100 x 100 y 125 x 125 cm entre líneas y plantas, respectivamente), con un diseño de bloques completos al azar, con cuatro repeticiones. Se midió el rendimiento de semilla pura (RSP), rendimiento de semilla pura germinable (RSPG), número de panículas m-2, longitud de panícula, número de semillas cosechadas por panícula, peso de 1,000 semillas, porcentaje de dehiscencia, semilla pura y germinación. El RSP y RSPG varió entre tratamientos (P0.05). Se concluye que el mayor rendimiento de semilla de B. brizantha cv. Marandu, se logró con la distancia 25 x 25 cm entre líneas y plantas, respectivamente. La germinación de la semilla no fue mejorada por ninguno de los tratamientos evaluados

Chemical treatments in maize seeds to improve germination in acidic soils

Objective: To evaluate the effect of different germination promoters on three maize genotypes grown in Dystric Cambisol soils, since germination problems are linked to latency and restrict agronomic management. Design/Methodology/Approach: We conducted an experiment at the Instituto Tecnológico Superior de Juan Rodríguez Clara using a split-plot design with a factorial treatment arrangement. The large plot contained genotypes (GEN) G1 = MS-405, G2 = Arlequin, and G3 = MS-404; while the small one comprised promoter (PROMO) HS = humic substance, CI = citrulline, and SA = salicylic acid. We evaluated the following variables: germination speed (GS), emergence percentage (EMERG), stem and leaf volume (S&amp;LV), root volume (RV), chlorophyll (CHL), secondary roots (SECR), stem diameter (DMT), number of leaves (NL), foliar area (FA), root length (RL), and plant height (PH). Then, we conducted a variance analysis and Tukey’s tests (α£0.05). Results: For each promoter, we observed main effects in EMERG, CHL, and PH for CI; S&amp;LV, NL, FA, and PH for HS; and RL for SA. In genotypes G2 and G3, variables GS, EMERG, NL, and PH were statistically equivalent, DMT varied only in G2, and there were no statistical differences for S&amp;LV, RV, CHL, SECR, FA, and RL. We observed some simple effects in combinations with CI: GS and PH varied in G3, EMERG in G2 and G3, CHL in G1 and G3, DMT in G1 and G2, and S&amp;LV in G2. Study limitations/Implications: Soaking corn for one hour in the solution and weighing the correct amount properly are required, since weighing too much may inhibit germination. Findings/Conclusions: Promoter CI at a dose of 1,000 ppm accelerates the emergence speed of genotypes G2 and G3 in acidic soils

Análisis de crecimiento del pasto Toledo Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster en clima cálido subhúmedo

Objective: Perform a growth analysis of Toledo grass (Urochloa brizantha CIAT 26110) during de rainy season, from sowing to 180 days, to determine the optimum harvesting moment. Design/methodology/approach: The morphological composition (CM), growth rate (GR), plant height, intercepted radiation (RI), leaf / stem ratio (L:S), leaf / non-leaf (L:NL), and biomass accumulation were evaluated every fifteen days during a 180 days period, except for the first two samples (monthly). Data were analyzed using the GLM procedure of SAS, under an experimental design of randomized blocks, with repeated measures over time, with three replicates.&nbsp; Results: The CM varied significantly (P&lt;0.01) through the different physiological states. The maximum production of aerial biomass (19.9 t DM ha-1) and GR (131.9 kg DM ha-1 day-1) were reached 150 days after sowing (dap) and that of leaves (3.9 t DM ha-1) was at 135 dap. At this time the RI was 100% and the height of plant was 106 cm. Limitations on study/implications: Toledo grass should be planted in the rainy season to be used when the canopy reaches a coverage greater than 80%, because the proportion of leaves decreases as the age of the plant progresses. Findings/conclusions: The highest accumulated total biomass, so it is suggested that the cut be made at 135 days after plantingObjetivo: realizar un análisis de crecimiento del pasto Toledo (Urochloa brizantha CIAT 26110) en la época de lluvias, desde la siembra hasta los 180 días, para determinar el momento óptimo de cosecha. Diseño/metodología/aproximación: Se evaluó la composición morfológica (CM), tasa de crecimiento (TC), altura de planta, radiación interceptada (RI), relación hoja/tallo (H:T), hoja/no hoja (H:NH) y la acumulación de biomasa aérea, a intervalos de quince días, a excepción de los dos primeros muestreos que fueron mensuales. Los datos fueron analizados mediante el procedimiento GLM de SAS, bajo un diseño experimental de bloques al azar, con medidas repetidas en el tiempo, con tres repeticiones. Resultados: La CM varió (P£0.01) a través de los diferentes estados fisiológicos. La máxima producción de biomasa aérea (19.9 t MS ha-1) y TC (131.9 kg MS ha-1 día-1) se alcanzó a los 150 días después de la siembra (dds), y la de hojas (3.9 t MS ha-1) fue a los 135 dds, en este momento la RI fue del 100% y la altura de 106 cm. Limitaciones del estudio/implicaciones: El pasto Toledo debe ser sembrado a inicio de la época de lluvias para ser usado cuando la cobertura del suelo sea mayor a 80 %, debido a que la proporción de hojas decrece conforme avanza la edad de la planta. Hallazgos/conclusiones: La máxima TC coincidió con la mayor biomasa total acumulada a los 135 (dds), por lo que se sugiere realizar el corte en este momento

Guidelines for the use and interpretation of assays for monitoring autophagy (4th edition)1.

In 2008, we published the first set of guidelines for standardizing research in autophagy. Since then, this topic has received increasing attention, and many scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Thus, it is important to formulate on a regular basis updated guidelines for monitoring autophagy in different organisms. Despite numerous reviews, there continues to be confusion regarding acceptable methods to evaluate autophagy, especially in multicellular eukaryotes. Here, we present a set of guidelines for investigators to select and interpret methods to examine autophagy and related processes, and for reviewers to provide realistic and reasonable critiques of reports that are focused on these processes. These guidelines are not meant to be a dogmatic set of rules, because the appropriateness of any assay largely depends on the question being asked and the system being used. Moreover, no individual assay is perfect for every situation, calling for the use of multiple techniques to properly monitor autophagy in each experimental setting. Finally, several core components of the autophagy machinery have been implicated in distinct autophagic processes (canonical and noncanonical autophagy), implying that genetic approaches to block autophagy should rely on targeting two or more autophagy-related genes that ideally participate in distinct steps of the pathway. Along similar lines, because multiple proteins involved in autophagy also regulate other cellular pathways including apoptosis, not all of them can be used as a specific marker for bona fide autophagic responses. Here, we critically discuss current methods of assessing autophagy and the information they can, or cannot, provide. Our ultimate goal is to encourage intellectual and technical innovation in the field

Recambio de tejido de hojas en Brachiaria humidicola CIAT 6133 con diferente manejo de la defoliación

The defoliation in the tissue replacement of Brachiaria humidicolaCIAT 6133 was evaluated by cuts at 9, 12 and 15 cm in height, harvested at 3, 4 and 5 and 5, 6 and 7 weeks in rains and norths, respectively. Every seven days the leaf appearance rate (LAR), leaf elongation rate (FER), leaf senescence rate (LSR) and net leaf growth (NFG) and stem density (DS) were measured every month. In rains, the highest LARwas 0.097 leaves stem-1day-1with cuts at 15 cm, every three weeks, in north 0.044 leaves stem-1day-1with cuts at 9 cm and 0.047 leaves stem-1day-1every seven weeks. The highest FERand NFGoccurred with cuts at 15 cm;in rains of 1.85 and 1.81, and in northsof 0.53 and 0.45 cm stem-1day-1, respectively. In rains the highest FERoccurred in week two of the regrowth (1.8 cm stem-1day-1), while in the north it was in week three of regrowth (0.45, 0.5 and 0.46 cm stem-1day-1). The LSRincreased from week four onwards in both seasons. The DSwas maximum at three and four weeks in rains and norths, at five and six weeks. The greatest leaf growth occurred in sections 15 cm high three weeks after regrowth, regardless of the interval between cuts and time of year, and the highest stem density at three and four weeks in rains and five and six weeks in northsSe evaluó la defoliación en el recambio de tejido de Brachiaria humidicola CIAT 6133 mediante cortes a 9, 12 y 15 cm de altura, cosechada a 3, 4 y 5 y 5, 6 y 7 semanas en lluvias y nortes, respectivamente. Cada siete días se midió: tasa de aparición de hojas (TAH), tasa de elongación foliar (TEF), tasa de senescencia foliar (TSF) y crecimiento neto foliar (CNF) y la densidad de tallos (DT) cada mes. En lluvias, la mayor TAH fue de 0.097 hojas tallo-1 día-1 con cortes a 15 cm, cada tres semanas, en nortes 0.044 hojas tallo-1 día-1 con cortes a 9 cm y 0.047 hojas tallo-1 día-1 cada siete semanas. Las mayores TEF y CNF ocurrieron con cortes a 15 cm; en lluvias de 1.85 y 1.81, y en nortes de 0.53 y 0.45 cm tallo-1 día-1, respectivamente. En lluvias las mayores TEF ocurrieron en la semana dos del rebrote (1.8 cm tallo-1 día-1), mientras que en nortes fue en la semana tres de rebrote (0.45, 0.5 y 0.46 cm tallo-1 día-1). La TSF se incrementó de la semana cuatro en adelante en ambas épocas. La DT fue máxima a tres y cuatro semanas en lluvias y nortes, a cinco y seis semanas. El mayor crecimiento foliar ocurrió en cortes a 15 cm de altura a las tres semanas del rebrote, independientemente del intervalo entre cortes y época del año y la mayor densidad de tallos a tres y cuatro semanas en lluvias y cinco y seis semanas en nortes