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Changes in body size spectra of benthic caridean shrimps (Decapoda: Caridea) and snails (Gastropoda) as response to seasonal variability

ERNESTO IVAN BADANO (2016)

"Ecologists have been largely interested in the description and understanding of the power scaling relationships between body size and abundance of organisms. Many studies have focused on estimating the exponents of these functions across taxonomic groups and spatial scales, to draw inferences about the processes underlying this pattern. The exponents of these functions usually approximate -3/4 at geographical scales, but they deviate from this value when smaller spatial extensions are considered. This has led to propose that body size-abundance relationships at small spatial scales may reflect the impact of environmental changes. This study tests this hypothesis by examining body size spectra of benthic shrimps (Decapoda: Caridea) and snails (Gastropoda) in the Tamiahua lagoon, a brackish body water located in the Eastern coast of Mexico. We measured water quality parameters (dissolved oxygen, salinity, pH, water temperature, sediment organic matter and chemical oxygen demand) and sampled benthic macrofauna during three different climatic conditions of the year (cold, dry and rainy season). Given the small size of most individuals in the benthic macrofaunal samples, we used body volume, instead of weight, to estimate their body size. Body size-abundance relationships of both taxonomic groups were described by tabulating data from each season into base-2 logarithmic body size bins. In both taxonomic groups, observed frequencies per body size class in each season were standardized to yield densities (i.e., individuals/m3). Nonlinear regression analyses were separately performed for each taxonomic group at each season to assess whether body size spectra followed power scaling functions. Additionally, for each taxonomic group, multiple regression analyses were used to determine whether these relationships varied among seasons. Our results indicated that, while body size-abundance relationships in both taxonomic groups followed power functions, the parameters defining the shape of these relationships varied among seasons. These variations in the parameters of the body size-abundance relationships seems to be related to changes in the abundance of individuals within the different body size classes, which seems to follow the seasonal changes that occur in the environmental conditions of the lagoon. Thus, we propose that these body size-abundance relationships are influenced by the frequency and intensity of environmental changes affecting this ecosystem."

Article

Allometry Energetic equivalence México Non-equilibrium, Power functions Seasonal changes BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA

Dinámica espacio-temporal de oxígeno-temperatura en los lagos Zempoala y Tonatiahua

JUDITH GARCIA RODRIGUEZ Migdalia Díaz Vargas (2012)

Los estudios nictimerales son particularmente importantes en los trópicos para conocer las variaciones ecológicas en ciclos diurnos, y no sólo en estacionales, y lo son no sólo desde el punto de vista conceptual, sino para la aplicación de planes de manejo en diferentes ambientes. El objetivo fue analizar las variaciones del oxígeno disuelto, porcentaje de saturación y temperatura en la columna de agua durante ciclos nictimerales, en los lagos Zempoala y Tonatiahua ubicados en el Parque Nacional Lagunas de Zempoala. Los mayores valores oxígeno disuelto, se presentaron en Zempoala, y la temperatura fue análoga en ambos lagos de acuerdo a los valores promedio totales. La variación de los parámetros estuvo directamente influenciada por la estacionalidad, su morfometría y entorno. El lago Zempoala se consideró como meromictico con tendencias a monomíctico cálido y Tonatiahua como

monomíctico cálido / Héctor Quiroz Castelán, Oliva Mondragón Eslava, Isela Molina Astudillo, Judith García Rodríguez y Migdalia Díaz Vargas.

The nictimeral studies are particularly important in the tropics, to know the ecology variations in diurnal cycles and not only in seasonal cycles. And this is not only from the conceptual point of view, rather for the application of management plans in different environments. The objective was to analyze the variations of dissolved oxygen, percentage of saturation and temperature in the water column during nictimeral cycles, in the lakes of Zempoala and Tonatiahua located in the National Park Lagunas de Zempoala. The greater values of oxygen appeared in Zempoala, and the temperature was analogous in both lakes according to the total values average. Variation of the parameters was directly influenced by the seasonal changes, its morphometry and surroundings. Zempoala lake was considered itself as meromictic with tendencies to warm monomictic and Tonatiahua as warm monomictic.

Article

CIENCIAS FÍSICO MATEMÁTICAS Y CIENCIAS DE LA TIERRA INGENIERÍA Y TECNOLOGÍA DEL MEDIO AMBIENTE Temperatura Oxígeno disuelto Estacionalidad Ciclos nictimerales Variaciones ecológicas Variación estacional Lago Zempoala (Morelos) Lago Tonatiahua (Morelos) Temperature Dissolved oxygen Seasonal changes Nictimeral cycles Ecological variations Seasonal variation

Cambios temporales de la biomasa y distribución de los mantos de Sargassum en la costa sureste de la península de Baja California

Temporal changes in the biomass and distribution of Sargassum beds along the southeastern coast of the Baja California Peninsula

MARIA MARGARITA CASAS VALDEZ IGNACIO SANCHEZ RODRIGUEZ ELISA SERVIERE ZARAGOZA RUTH NOEMI AGUILA RAMIREZ (2016)

"Changes in the distribution, surface canopy, biomass, and standing crop of Sargassum beds (Phaeophyceae) along the southeastern coast of the Baja California Peninsula (Mexico) are described and compared with previous estimates. Also, Sargassum biomass was correlated with latitude. Species were identified and surface canopy, biomass, standing crop, and length structure were estimated for 72 Sargassum beds in 3 localities in 2006. The extent of each bed was determined using GPS. The perimeter of each bed was drawn and its canopy area was calculated. The average biomass was estimated, using quadrats that were randomly distributed over the beds. The highest average biomass was found at Mulegé, with significant differences in the other 2 study areas (Concepción and La Paz bays). The largest bed, surface canopy area, and standing crop were recorded in Concepción Bay. Coverage area, location, and seasonal changes in surface canopy, standing crop, and biomass of Sargassum beds along the southeastern coast of the Baja California Peninsula were compared with the different phenological stages of Sargassum thalli, variations in the available rocky sea floor, and oceanographic characteristics. These aspects must be considered to maintain sustainable exploitation of this potential resource."

"Se describen y comparan con estimaciones previas los cambios en la distribución, superficie, biomasa y cosecha de mantos de Sargassum (Phaeophyceae) a lo largo de la costa sureste de la península de Baja California (México). También, la biomasa de Sargassum se correlacionó con la latitud. Se determinaron las especies y se estimó la superficie, biomasa, cosecha y estructura de tallas de 72 mantos de Sargassum en 3 zonas en 2006. La extensión de cada manto fue determinada usando GPS. El perímetro de cada manto fue dibujado y su superficie fue calculada. La biomasa promedio fue estimada usando cuadrantes que fueron distribuidos al azar sobre los mantos. Se registró la biomasa promedio más alta en Mulegé, encontrándose diferencias significativas con respecto a las otras 2 zonas de estudio (bahías Concepción y La Paz). En bahía Concepción se registró el manto más grande y la mayor superficie y cosecha. Los cambios en la distribución, superficie, biomasa y cosecha de los mantos de Sargassum a lo largo de la costa sureste de la península de Baja California fueron comparados con diferentes estadios fenológicos de Sargassum, variaciones en la disponibilidad de sustrato rocoso y características oceanográficas. Estos aspectos deben ser considerados para mantener una explotación sustentable de este recurso potencial."

Article

biomass, Gulf of California, Sargassum, standing crop, seasonal changes biomasa, golfo de California, cosecha, cambios estacionales BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA VEGETAL (BOTÁNICA) ALGOLOGÍA (FICOLOGÍA)

Modificación de la célula nodriza de Trichinella spiralis en ratas Long Evans inmunizadas con antígeno soluble total de Trichinella spiralis y sacrificadas en diferentes tiempos

LUIS ALEJANDRO AGUILERA GALAVIZ (2012)

The purpose of this study was to evaluate the changes in the T. spiralis’ nurse cell in Long Evans rats

immunized with Total Soluble Antigen T. spiralis sacrificed at different times. We worked with 25 male rats

of two and a half months old, immunizing 20 of them. Then, the 25 rats were challenged with meat infected

with T. spiralis, making the sacrifice of five rats each month, plus a rat control during 4 months to slaughter

it; the techniques are carried out directly: on-board compression, artificial digestion and Hematoxylin-

Eosin; indirect techniques of MIDD and Western Blot were applied for the serums. The result: a reduction

in worm load. The maximum effects of protection were observed in the ultimate sacrifice after spending

four months. The most obvious change to the nurse cell was a modification of the cyst and parasite’s spiral

loss. Changes in the nurse cell of T. spiralis in Long Evans rats’ tissues immunized with AST and sacrificed

at different times were evident with direct techniques of C/P, D/A and staining of H/E, we observed that the

encystment was lost and the spiral was no longer viable, being statistically significant (P ≤ than 0.01).

Key words: Trichinella spiralis, nurse cell, changes, TSA, different times.

El propósito de este trabajo fue evaluar las modificaciones de la célula nodriza de T. spiralis en ratas

Long Evans inmunizadas con Antígeno Soluble Total de T. spiralis y sacrificadas en diferentes tiempos.

Se trabajó con 25 ratas macho de 2 meses y medio de edad, inmunizando 20. Posteriormente las 25 ratas fueron retadas con carne infectada de T. spiralis, realizando el sacrificio de 5 ratas cada mes, más una

rata control por 4 meses, al sacrificarlas se les realizó técnicas directas de compresión en placa, digestión

artificial y la técnica de Hematoxilina-Eosina; a los sueros se les realizó técnicas indirectas de MIDD

y Western Blot. Se obtuvo una disminución en la carga parasitaria. El efecto máximo de protección se

observó en el último sacrificio después de haber transcurrido 4 meses. La modificación más evidente a la

célula nodriza fue la modificación del quiste y pérdida del espiral del parásito. Las modificaciones en la

célula nodriza de T. spiralis en tejidos de rata Long Evans inmunizadas con AST y sacrificadas en diferentes

tiempos fue evidente con las técnicas directas de C/P, D/A y la tinción de H/E, se observa cómo se pierde

el enquistamiento y la espiral ya no es viable, siendo estadísticamente significativo con un valor de P < de

0,01.

Producción Científica de la Universidad Autónoma de Zacatecas UAZ

Article

BIOLOGÍA Y QUÍMICA Trichinella spiralis nurse cell changes TSA different times célula nodriza modificación AST diferentes tiempos

Política agrícola y heladas en el medio rural : caso de los productores de maíz en Tlachichuca, Puebla

MONICA RAMIREZ HUERTA (2013)

Tesis (Maestría en Ciencias, especialista en Estrategias para el Desarrollo Agrícola Regional).- Colegio de Postgraduados, 2013.

El objetivo de esta investigación fue analizar la distribución espacial de las heladas en el estado de Puebla y la importancia de la política agrícola ante las heladas en la producción de maíz de temporal en el municipio de Tlachichuca, Puebla en 2011. En la investigación se realizó una revisión bibliográfica, recorridos de campo y se elaboró una base de datos para relacionar la presencia de heladas y pobreza en los 217 municipios del estado de Puebla, también se aplicó un cuestionario a 76 agricultores afectados por helada en Tlachichuca. Los resultados mostraron que espacialmente la mayor superficie dañada en el cultivo del maíz y con alto porcentaje de pobreza en su población fue el Valle de Serdán. En el municipio de Tlachichuca, el 94.7% de los entrevistados posee ejidos y un promedio de 5.26 hectáreas; el 93.4% presentó heladas en sus tierras, ninguno contrató un seguro agrícola, ante ello el Componente Atención de Desastres Naturales (CADENA) benefició a 73.7% de los entrevistados recibiendo un apoyo de $3096.43 en 2.59 hectáreas promedio. El 92.9% utilizó el apoyo económico en su alimentación y pago de deudas, ya que para financiar sus necesidades básicas 64.5% utilizó PROCAMPO, 22.3% vendió sus animales y pidió prestado, 7.9% vendió la cosecha anterior y 5.9% migró. Se concluye que la política agrícola, bajo el modelo económico neoliberal en el cual se desenvuelve, solo mitigó los daños causados por la helada a los productores de maíz. _______________ AGRICULTURAL POLICY AND FROSTS IN THE RURAL SPACE: CASE OF PRODUCERS OF CORN IN TLACICHUCA, PUEBLA. ABSTRACT: The objective of the research was to analyze the spatial distribution of frosts in the state of Puebla and the importance of agricultural policy in frosts on seasonal maize production in the municipality of Tlachichuca in 2011. The research involved a statics review, field observations and developed data base to relate the presence the frosts and poverty in the 217 municipalities of state Puebla, as well as a questionnaire applied to 76 producers affected by the frosts in Tlachichuca. The results showed that spatially the most damaged surface of maize cultivation with a high percentage of poverty in population was the Valle de Serdan. In the municipality of Tlachichuca, 94.7% of respondents has village owned collective farm and an average 5.26 hectares, 93.4% had frosts of their land; nobody took on agricultural insurance, to this the Component Attention to Natural Disasters (CADENA) 73% benefited of respondents getting a support $3096.43on average 2.59 hectares. The 92.9% use the financial support for food and paying debts so that to finance their basic needs, 64.5% used PROCAMPO, 22.3% sold their animals and borrowed, 7.9% sold the previous harvest and 5.9% emigrated. It conclude that agricultural policy because the neoliberal economic model only mitigated the damage caused by frosts to corn producer in which it operates.

Master thesis

Agricultura de temporal Campesino Pobreza Siniestro Peasant Poverty Seasonal agriculture Sinister Maestría EDAR Estrategias para el Desarrollo Agrícola Regional CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Impact of season of harvest on in vitro gas production and dry matter degradability of Acacia saligna leaves with inoculum from three ruminant species

Abdelfattah Zeidan Mohamed Salem (2005)

In vitro gas production (IVGP) and dry matter degradability (IVDMD) of Acacia saligna leaves (ASL) from four seasons were studied under arid Egyptian conditions as a 4×3 factorial experiment (4 seasons×3 ruminant species). Incubations were completed using rumen liquid collected immediately after slaughter from sheep, cattle and buffalo, in order to investigate differences among ruminants in their ASL fermentation capacity. Samples of ASL were collected during the last 2 months of each season, being autumn, winter, spring and summer (between the 5th and 12th week of each season). Dried samples of ASL were incubated for 24 h in each of the three buffered rumen liquors, using a syringe technique, to determine IVGP and IVDMD. The crude protein content of ASL was lower (P<0.01) in summer (143 g/kg DM) than autumn (171 g/kg DM), winter (177 g/kg DM) and spring (182 g/kg DM). In winter, ASL had lower neutral detergent fibre, acid detergent fibre, acid detergent lignin and cellulose than in other seasons (P<0.05), but there were no differences among seasons in ash and hemicellulose contents. Condensed tannin (CT, as quebracho tannin equivalent) contents of ASL were higher (P<0.001) in summer (113 g/kg DM) versus the other seasons, with the lowest value during winter (63 g/kg DM). Gas production after 24 h was higher (P<0.05) with buffalo rumen fluid, versus cattle or sheep, in all seasons except winter. IVGP with buffalo rumen fluid was not affected by season but, with cattle and sheep, IVGP was higher (P<0.01) in winter. IVDMD was higher in winter and spring, and lower in summer and autumn, within all species, and higher (P<0.001) values were general with buffalo versus other species. IVGP was positively (P<0.05) correlated with IVDMD, but there was no consistent relationship between IVGP or IVDMD and chemical composition of ASL. Rumen fluid from buffalo, cattle and sheep have different capacities to ferment A. saligna leaves, and differences among species were smallest in winter, when the fibre and CT contents of ASL were lower. © 2005 Elsevier B.V. All rights reserved.

Article

Seasonal variation Acacia saligna Condensed tannins Gas production Dry matter degradability Buffalo Cattle Sheep BIOLOGÍA Y QUÍMICA

Disponibilidad de forraje en un sistema silvopastoril con distintas densidades de Leucaena leucocephala L., bajo pastoreo regenerativo.

IVÁN AZUARA MORALES (2019)

Tesis (Maestría en Ciencias, especialista en Agroecosistemas Tropicales).- Colegio de Postgraduados, 2019.

Se determinó la biomasa forrajera disponible, composición química del forraje, capacidad de carga, composición botánica y tiempo de recuperación de las plantas después del pastoreo, en un sistema silvopastoril con 15000 (D15) y 25000 árboles ha-1 (D25) de Leucaena leucocephala, manejados con pastoreo regenerativo. Se utilizó un diseño de bloques completos al azar con dos repeticiones. Los muestreos de biomasa se hicieron de julio 2017 a julio 2018, cuando el pasto (en lluvias y transición) o el árbol (estiaje) se encontraban en el punto óptimo de reposo y se pastorearon ovinos pelibuey (carga animal instantánea: 34 a 204 UGM ha-1 según la época). La biomasa total disponible fue más alta en D25 (15957 kg MS ha-1; p<0.05) con mayor capacidad de carga (2.9 UGM ha-1 año-1); en época seca se produjeron 484 y 537 kg DM ha-1 en D15 y D25, respectivamente, procedente solo de los árboles. El periodo de reposo de los potreros varió según la época de pastoreo de 31 a 120 días; 59 a 65 % de la biomasa la constituyó el pasto en época de transición y lluvias, mientras que en secas el 100 % fue árbol. El contenido de proteína cruda fue mayor en los árboles (24 %) que en pasto (10 %). Se concluye que en sitios con mayor densidad de árboles y pastoreo regenerativo se incrementa la biomasa forrajera, y se mantiene el crecimiento de las plantas a través del año aun con precipitación estacional porque las especies crecen alternadamente. _______________ AVAILABILITY OF FORAGE IN A SILVOPASTORIL SYSTEM WITH DIFFERENT DENSITIES OF Leucaena leucocephala L., UNDER REGENERATIVE GRAZING. ABSTRACT: We determined the available forage biomass, forage chemical composition, carrying capacity, botanical composition and recovery time of the plants after grazing, in a silvopastoral system with 15000 (D15) and 25000 trees ha-1 (D25) of Leucaena leucocephala, using regenerative grazing. A randomized complete block design with two replicates was used. Biomass samplings was performed from July 2017 to July 2018, when the grass (during the in rain and transition seasons) or the tree (dry season) were at the optimal rest time and pelibuey sheep were grazed (instant stocking rate of 34 and 204 UGM ha-1 in dry and rainy respectively). The total available biomass was higher in D25 (15957 kg DM ha-1; p <0.05) as well as carrying capacity (2.9 UGM ha-1 year-1); in the dry season 484 and 537 kg DM ha-1 were produced in D15 and D25, respectively, provided only from the trees. The resting time ranged according to the grazing season from 31 to 120 days. From 59 to 65% of the biomass was grass in the transitional and rainy seasons and 100% was tree forage in the dry season. Crude protein was higher in tree (24%) than in grass forage (10%). It is concluded that in places with higher density of trees and using regenerative grazing, the forage biomass increases, and there is plant growth throughout the year even under seasonal precipitation conditions, because the trees and grasses grow alternately throughout the seasons.

Master thesis

Capacidad de carga Composición botánica Precipitación estacional Botanical composition Carrying capacity Chemical composition Seasonal precipitation Agroecosistemas Tropicales Maestría CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS AGRONOMÍA PASTOS

Mycorrhizal dynamics and dependence of Desmoncus orthacanthos Martius (Arecaceae), a native palm of the Yucatan Peninsula, Mexico

JOSE ALBERTO RAMOS ZAPATA ROGER ARMANDO ANTONIO ORELLANA LANZA (2006)

Field observations were carried out to determine the seasonal patterns and recovery from disturbance by arbuscular mycorrhizal (AM) associations in Desmoncus orthacanthos Martius, eight years following shifting agriculture and in a mature forest. In addition, a greenhouse experiment was performed to determine the relative mycorrhizal dependency (RMD) of this species. Four growth stages were selected, and roots and rhizosphere soil of five individuals from each stage were monitored during one year. A seasonal pattern, but no difference in abandoned agriculture and mature forest were found in AM fungal activity. Soil moisture, spores per gram of soil, and percentage of root colonization were not correlated during this year. Root colonization was highest at both sites during the wet season, but was equally high during one dry season observation in the abandoned milpa. Spore density was highest during the dry season. The RMD ranged from 7.8 to 54.9%, with greater biomass of mycorrhizal than non-mycorrhizal plants using P solutions that mimicked field soil concentrations. This suggests that this slow-growing palm is highly dependent on mycorrhizal fungi in local soils and maintains relatively high AM activity even during the dry season. Culture of this slow-growing, understory palm for the rattan industry requires that soils be managed for high levels of AM fungi. Thestudy showed that the standard local practice of shifting agriculture enables sufficient recovery of soil inoculum for growth of D. orthacanthos. 

Article

ARBUSCULAR MYCORRHIZA DEPENDENCY SEASONAL PATTERNS UNDERSTORY PALMS BIOLOGÍA Y QUÍMICA

Volatilidad de precios en el sector frutícola de México : El caso de la naranja

Price volatility in the Mexican fruit sector: The case of the orange

ALEJANDRO MARTINEZ JIMENEZ José Alberto García Salazar (2020)

Para determinar la existencia del componente estacional (CE) y cíclico en el precio al mayoreo de la naranja, se realizó un análisis de precios en las centrales de abasto de la Ciudad de México, Guadalajara y Monterrey en el periodo septiembre de 2000 a agosto de 2017. Los resultados indican que el índice estacional (IE) alcanza su valor máximo entre junio y septiembre en las tres centrales de abasto. Las diferencias máximas entre el precio real y el precio desestacionalizado indican la presencia de un fuerte CE. También se detectó la presencia de seis ciclos con una duración promedio de 18, 16 y 18 meses para las tres centrales de abasto. Para evitar la volatilidad en el precio de la naranja, se recomienda planear la producción en el espacio y tiempo, así como promover la industrialización de la naranja.

To determine the existence of the seasonal and cyclical component in the wholesale price of oranges, a price analysis was carried out at the supply centers of Mexico City, Guadalajara, and Monterrey from September 2000 to August 2017. The results indicate that the seasonal index reaches its maximum value between June and September in the three supply centers. The maximum differences between the real price and the seasonally adjusted price indicate the presence of a strong seasonal component. Moreover, six cycles with an average duration of 18, 16, and 18 months for the three supply centers were also detected. To avoid the volatility in the price of oranges, it is recommended to plan the production in space and time, as well as to promote the industrialization of oranges.

Article

CIENCIAS SOCIALES CIENCIAS ECONÓMICAS ECONOMETRÍA Volatilidad de precios Precio al mayoreo Indice estacional Componente estacional Componente cíclico Naranja - Precios Price volatility Wholesale price Seasonal index Seasonal component Cyclical component Orange - Prices

Rendimiento y características agronómicas de cruzas interraciales de maíz adaptado a Valles Altos.

ANGELA MANUELA VELASCO GARCIA (2018)

Tesis (Maestría en Ciencias, especialista en Genética).- Colegio de Postgraduados, 2018.

El germoplasma exótico de maíz (Zea mays L.) es una fuente de alelos favorables para el mejoramiento genético, pero antes de ser empleado debe ser adaptado a las condiciones ambientales de interés. El objetivo de la investigación fue evaluar agronómicamente poblaciones de maíz exótico adaptado a Valles Altos y sus respectivas cruzas interraciales. Para lo anterior, se realizaron dos estudios. El primero consistió en evaluar nueve poblaciones adaptadas de maíz exótico adaptado a Valles Altos, ocho de sus cruzas simples, una cruza triple, generaciones avanzadas de las cruzas y cuatro testigos. Se registró el rendimiento y seis de sus componentes. Se tuvo significancia (P ≤ 0.01) entre genotipos para todos los caracteres; los materiales exóticos rindieron de 3.89 a 11.17 t ha-1 y los testigos de 8.06 a 11.56 t ha-1. El rendimiento de los testigos y del Tuxpeño se correlacionó con longitud y diámetro de mazorca y número de granos por hilera. La heterosis promedio para rendimiento y sus componentes fluctuó de -5.30 a 6.53 %; fue positiva para rendimiento (5.68 %) con valores individuales de 4.3 a 26.19 %, por lo que el rendimiento de las cruzas aumentó. La segunda investigación consistió en evaluar los genotipos antes mencionados y nueve poblaciones originales. Para lo anterior, se registraron 28 caracteres cualitativos y cuantitativos. Mediante análisis de componentes principales y agrupamiento jerárquico, se identificaron seis grupos con base en caracteres de rendimiento, precocidad, estructura morfológica y características de mazorca. Las poblaciones originales mostraron poca adaptación a Valles Altos al incrementar su altura, días a floración y disminuir su rendimiento; sin embargo, la metodología de selección empleada permitió obtener poblaciones con mejores características de rendimiento de mazorca, menos días a floración, menor altura de planta, menor número de ramas primarias de espiga y mazorcas de forma cónica. Con ambos estudios, se concluyó que el germoplasma exótico y sus cruzas presentaron características de interés, por esto podrían ser empleadas per se o como progenitores para el mejoramiento genético del maíz para Valles Altos. _______________ YIELD AND AGRONOMIC CHARACTERISTICS OF INTERRACIAL MAIZE CROSSES ADAPTED TO HIGH VALLEYS. ABSTRACT: Exotic maize germplasm (Zea mays L.) is a source of novel alleles for genetic improvement, but before being used exotic germplasm must be adapted to the environmental conditions of interest. The objective of this study was to evaluate agronomically populations of exotic maize adapted to High Valleys and their respective interracial crosses. For that reason, we carried out two studies. The first one was to evaluate nine adapted populations of exotic maize, eight of its single crosses, a triple cross, advanced generations of the crosses and four controles. Grain yield and six of its components were recorded. Statistical significance (P ≤ 0.01) among genotypes were found for all traits; the exotic materials yielded from 3.89 to 11.17 t ha-1 and the controles from 8.06 to 11.56 t ha-1. Grain yield of the controles and Tuxpeño were correlated with length and diameter of ear and number of grains per row. The average heterosis for yield and its components fluctuated from -5.30 to 6.53 %, and it was positive for yield (5.68 %) with individual values from 4.3 to 26.2 %, so that the yield of the crosses increased. In the second work we evaluated the same genotypes previously mentioned and nine original populations. For these, 28 quantitative and qualitative characters were recorded. Analysis of principal components and hierarchical clustering identified six groups based on yield performance, earliness, morphological structure and ear characteristics. The original populations showed little adaptation to High Valleys as they increased its plant height, days to flowering and decreased its yield. However, recurrent selection allowed to obtain populations with better yield components, fewer days to flowering, lower plant height, fewer tassel primary stem branches and cone-shaped ears. In both studies, it was concluded that exotic germplasm and their crosses showed characteristics of interest because these could be employed as varieties per se or as parents for genetic improvement of the local maize from High Valleys.

Master thesis

Zea Mays L. adaptación Cambios adaptativos Poblaciones exóticas Rendimiento Selección Variabilidad Zea Mays L. adaptation Adaptive changes Yield Exotic populations Selection Variability Genética Maestría CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS AGRONOMÍA PRODUCCIÓN DE CULTIVOS