Advanced search


Knowledge area




78 results, page 1 of 8

Atributos demográficos y biología reproductiva de Coryphantha cornifera y Stenocactus anfractuosus con fines de conservación

VLADIMIR FUENTES MAYO (2012)

Tesis (Doctorado en Ciencias, especialista en Botánica).- Colegio de Postgraduados, 2012.

Se estudió la distribución geográfica, asociación, densidad, supervivencia in situ y factores de riesgo para las poblaciones de Coryphantha cornifera y Stenocactus anfractuosus. La búsqueda de las especies se hizo mediante recorridos de campo en los estados de México, Hidalgo, Tlaxcala, Puebla y Querétaro. En los sitios donde se encontraron estas especies, se registraron las coordenadas geográficas y altitud. Se establecieron parcelas de 400 m2 donde se marcaron todos los individuos presentes; para cada uno se obtuvieron datos morfométricos y número de costillas o tubérculos; también se registró la ocupación del hábitat, el estado fenológico y la condición sanitaria. Las plantas fueron censadas cada tres meses. C. cornifera y S. anfractuosus se encontraron solo en dos de los cinco estados visitados: Hidalgo y México, de los 2, 136 hasta los 2, 443 m snm. La densidad para cada especie varió de una hasta 366 plantas en 400 m2. Ambas especies comparten el hábitat y se establecen en sitios con luz plena. En todas las unidades de muestreo evaluadas, la supervivencia in situ fue decreciendo. El clandestinaje fue la principal causa de desaparición de ambas especies. Este es el primer diagnóstico sobre poblaciones de C. cornifera y S. anfractuosus que pretende brindar información básica sobre la gestión y conservación de estas cactáceas. _______________ We studied the geographical, spatial distribution, density, in situ survival, and risk factors of the populations of Coryphantha cornifera and Stenocactus anfractuosus in situ. Trips were taken in the states of México, Hidalgo, Tlaxcala, Puebla and Querétaro. At sites where species were studied, we recorded the geographic coordinates and altitude. Four hundred m2 plots were established which marked all individuals present, for each obtained morphometry, habitat occupation, phenology and health status. Plants were censured every three months. C. cornifera and S. anfractuosus were found only in the states of Hidalgo and Mexico from 2, 136 up to 2, 443 m. The density of each species ranged from one to 366 plants per 400 m2. Both species share the habitat and prefer the open spaces. It was observed that in situ survival was decreasing in all the plots evaluated. The illegal extraction was the main cause of disappearance or death of both species. This is the first diagnosis of the populations of C. cornifera and S. anfractuosus which aims to provide the basic information of management and conservation programs of these cacti.

Doctoral thesis

Distribución geográfica Densidad Riesgo Cactáceas Doctorado Botánica Globose cacti Mexico Reproductive traits Mating systems Doctorado Botánica CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Stability in performance of quality protein maize under abiotic stress

Pervez Zaidi Ravi Singh (2008)

Quality protein maize (QPM) has emerged an affordable and viable option to alleviate protein mal-nutrition and reduce animal feed costs, given that its grain protein contains more than double the lysine and tryptophan concentrations of normal endosperm maize. For commercial success, QPM cultivars must be competitive with normal maize in productivity and should show stable performance across environments, especially with respect to yield and protein quality traits. In the tropics, drought and low-nitrogen (N) fertility are major constraints to maize productivity. In this study, we analyze the stability of performance of CIMMYT tropical and subtropical elite QPM hybrids across stressed (drought and low N) and unstressed environments. In general, stress significantly affected all agronomic traits except male flowering. The effect was comparatively large under drought stress. Among the quality traits, grain protein, tryptophan, and lysine contents showed significant variation across environments. There was an increase in grain protein (12.7%) and in lysine (10.3%) and tryptophan contents (8.1%) under drought stress, while levels of these grain quality traits were reduced under low N by 17.0, 12.5, and 15.6%, respectively. However, the effect of stressed environments was comparatively small on protein quality traits, including tryptophan and lysine content in protein. The variation in protein quality across environments was statistically significant but largely due to genotypic variability. Variation due to environment and genotype by environment (G x E) interaction was statistically non-significant for protein quality traits, except in the case of lysine content in protein, where G x E was significant. Our results suggest that grain yield and grain protein content are the most unstable traits, whereas tryptophan followed by lysine content are the most stable, across stressed and unstressed evironments.

Article

Quality protein maize Drought Nitrogen Maize Quality Traits CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Evaluación preliminar productiva de tres razas paternas en características de la canal de corderos para producción de carne en Hidalgo, México.

MARIA MONSERRAT LOPEZ VELAZQUEZ (2015)

Tesis (Maestría en Ciencias, especialista en Ganadería).- Colegio de Postgraduados, 2015.

El objetivo del estudio fue evaluar el efecto de la raza paterna (Charollais, Dorset, y Texel), sexo y tipo de nacimiento de la cría, así como número de parto de la madre en ovejas Hampshire, en diferentes características de la canal de sus corderos. Después del destete (74±8 días), 45 corderos de estas cruzas fueron finalizados durante 63 días, consumiendo una dieta comercial con 14% de PC y 2.82 Mcal de EM/kg de MS. Los corderos se sacrificaron a los 137 días de edad; posteriormente, se tomaron medidas de peso al sacrificio (PS), peso (PCC) y rendimiento de canal caliente (RCC), peso (PCF) y rendimiento de canal fría (RCF), área ojo de chuleta (AOC), espesor de grasa subcutánea (EGS), longitud externa (LEC) e interna de canal (LIC), longitud de pierna (LP), perímetro de grupa (PG), índice compacidad externa (ICEC) e interna de canal (ICIC), así como pesos y rendimientos de la composición regional de la canal (espaldilla, bajos, badal, pierna, cuello, y costillar). Los datos se analizaron utilizando un modelo mixto. Los corderos de padre Charollais tuvieron el mayor (P≤0.05) AOC (20.1±0.5 cm2), mientras que los de padre Dorset fueron superiores (P≤0.05) en LIC (66.3±0.9 cm) y LP (34.8±0.3 cm). Los machos superaron a las hembras (P≤0.05) en la mayoría de las variables analizadas. Los corderos de parto sencillo tuvieron medias mayores que los de parto doble (P≤0.05) en EGS y LP. En general, las razas Charollais y Dorset mostraron superioridad en las características de la canal de su progenie. _______________ EFFECT OF SIRE BREED ON CARCASS TRAITS OF LAMBS IN A MEAT COMMERCIAL PRODUCTION SYSTEM IN HIDALGO, MÉXICO. ABSTRACT: The main objective of the study was to evaluate the effect of sire breed (Charollais, Dorset and Texel), lamb sex and birth type, as well as Hampshire ewe’s lambing number, on different carcass traits of their lambs. After weaning (74±8 d), 45 lambs from these crosses were fed during 63 d, consuming a commercial diet with 14% CP and 2.82 Mcal of ME/kg of DM. Lambs were slaughtered at 137d of age; later, measures on slaughter weight (SW), hot carcass weight (HCW) and yield (HCY), cold carcass weight (CCW) and yield (CCY), rib eye area (REA), subcutaneous fat (SF), external (ECL) and Internal carcass length (ICL), leg length (LL), rump perimeter (RP), external (ECCI) and internal carcass compactness index (ICCI), as well as weights and yields of the carcass regional composition (shoulder, chest-belly, anterior-loin, leg, neck, and rear-loin) were taken. Data were analyzed utilizing a mixed model. Charollais-sired lambs had the highest (P≤0.05) REA (20.1±0.5 cm2), while Dorset-sired lambs were superior (P≤0.05) in ICL (66.3±0.9 cm) and LL (34.8±0.3 cm). Ram lambs surpassed ewe lambs (P≤0.05) in the majority of analyzed variables. Lambs born as singles had higher means than twin lambs (P≤0.05) in SF and LL. In general, Charollais and Dorset breeds showed superiority in carcass traits of their progeny.

Master thesis

Ovinos de carne Razas paternas Cruzamientos Características de la canal Composición regional Meat sheep Paternal breeds Crossbreeding Carcass traits Regional composition Ganadería Maestría CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS PRODUCCIÓN ANIMAL OVINOS

Diversidad morfológica de maíces nativos (Zea mays L) en el trópico húmedo poblano: magnitud y usos

FERNANDO LOPEZ MORALES (2012)

Tesis (Maestría en Ciencias, especialista en Estrategias para el Desarrollo Agrícola Regional).- Colegio de Postgraduados, 2012.

La diversidad del maíz es tal que en cada región de México existen variedades locales adaptadas a las condiciones climáticas, edáficas, altitudinales y de manejo, bajo las cuales se está produciendo este cultivo. Por esta razón se ha planteado que la actual diversidad genética presente en las poblaciones locales de maíz, ha sido el producto de la interacción entre las diferentes culturas étnicas y las diversas condiciones ambientales que crean los agroecosistemas en las regiones de temporal. Por lo tanto, este estudio tuvo por objetivo general el estudiar la diversidad morfológica y de usos de los maíces nativos cultivados en cuatro municipios del trópico húmedo de Puebla: Tenampulco, Ayotoxco de Guerrero, Hueytamalco y San José Acateno. Para ello, durante el año 2008 se realizó una colecta de poblaciones nativas de maíz en la región y simultáneamente se aplicó un cuestionario a los agricultores donantes de muestras. A finales del 2009 se establecieron dos experimentos, utilizando un diseño látice 10 × 10 con dos repeticiones, en los cuales se evaluaron 93 poblaciones nativas, una accesión representativa de la raza Tuxpeño (Vera-39) y seis materiales mejorados. Se midieron en total 51 caracteres, entre vegetativos, agronómicos, de espiga, de totomoxtle, de mazorca, de grano y se calcularon diversos índices. Se realizaron análisis de varianza, de correlación, de componentes principales y de conglomerados para definir la diversidad morfológica y precisar la correspondencia de las poblaciones locales con el tipo racial tuxpeño. Las encuestas aplicadas a 93 productores fueron codificadas y analizadas. Los principales resultados fueron los siguientes: 1) existe una gran diversidad morfológica y de usos en los maíces nativos cultivados en el trópico húmedo poblano; 2) los maíces nativos cultivados en esta región pueden considerarse como pertenecientes a la raza Tuxpeño; 3) en principio, la diversidad de los maíces nativos puede agruparse por coloración de grano (blanco, amarillo, azul y rojo) y niveles de precocidad (precoz, intermedio y tardío); 4) los usos más frecuentes del maíz, independientemente del color de grano, fueron: elaboración de tortilla, atole, tamales, elote, hoja para tamal y alimento para animales. _______________ MORPHOLOGICAL DIVERSITY OF NATIVE MAIZE (Zea mays L.) POPULATIONS IN THE HUMID TROPICS OF PUEBLA, MEXICO: MAGNITUDE AND USES. ABSTRACT: Maize diversity is such that in each region of Mexico there are local varieties adapted to the climate, soil, altitude and management conditions, under which this crop is produced. For this reason, it has been suggested that the genetic diversity currently present in local populations of maize has been the product of the interaction between the different ethnicities and the diverse environmental conditions that create agroecosystems in rain-fed regions. Therefore, this study was aimed to explore the morphological diversity and uses of the native maize populations grown at four municipalities in the humid tropics of Puebla: Tenampulco, Ayotoxco de Guerrero, Hueytamalco and San Jose Acateno. Thus, during the year 2008, a collection of native maize populations was performed in the region; at the same time, a questionnaire was applied to the sample donors-farmers. At the end of 2009, two experiments were established, under a 10 × 10 lattice design with two replications. A total of 93 native populations were evaluated in each one, as well as one accession representative of the Tuxpeño race (Vera-39) and six improved materials. A total of 51 characters, including vegetative, agronomic, of the tassel, corn husk, cob and grain traits were measured, and various indexes were calculated. To study the morphological diversity and decide over the correspondence of local populations with the Tuxpeño race, statistical analyses were conducted, including analysis of variance, correlation, principal components and cluster analysis. The surveys of 93 producers were coded and analyzed. The main results were: 1) exists a large morphological diversity and of uses among the landraces cultivated in the humid tropics of Puebla, 2) the landraces cultivated in this region can be considered as belonging to the Tuxpeño race, 3) initially, the landrace diversity can be grouped by grain color (white, yellow, blue and red) and precocity (early, intermediate and late), 4) the most frequent uses of corn, regardless of grain color, were : tortillas, atole, tamales, fresh corn, corn husk and stubble.

Master thesis

Características agronómicas Caracterización morfológica Correspondencia racial Poblaciones nativas Usos Agronomic traits Landraces Morphological characterization Racial correspondence Uses EDAR Estrategias para el Desarrollo Agrícola Regional Maestría CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Biotic and abiotic factors associated with altitudinal variation in plant traits and herbivory in a dominant oak species

LUIS ALEJANDRO ABDALA ROBERTS SERGIO RASMANN JORGE C. BERNY MIER Y TERAN MARíA FELISA COVELO NúñEZ GAETAN GLAUSER XOAQUíN MOREIRA (2016)

PREMISE OF THE STUDY: It is generally thought that herbivore pressure is higher at lower elevations where climate is warmer and less seasonal, and that this has led to higher levels of plant defense investment at low elevations. However, the generality of this expectation has been called into question by recent studies. METHODS: We tested for altitudinal gradients in insect leaf damage, plant defenses (phenolic compounds), and nutritional traits (phosphorus and nitrogen) in leaves of the long-lived tree Quercus robur , and further investigated the abiotic factors associated with such gradients. We sampled 20 populations of Q. robur distributed along an altitudinal gradient spanning 35–869 m above sea level, which covered most of the altitudinal range of this species and varied substantially in abiotic conditions, plant traits, and herbivory. KEY RESULTS: Univariate regressions showed that leaf herbivory, phenolics, and phosphorus increased toward higher elevations, whereas leaf nitrogen did not vary with altitude. Multiple regression analyses indicated that temperature was the single most important factor associated with herbivory and appears to be strongly associated with altitudinal variation in damage. Leaf phenolics were also correlated with herbivory, but in a manner that suggests these chemical defenses do not underlie altitudinal variation in damage. In addition, we found that variation in leaf traits (phenolics and nutrients) was in turn associated with both climatic and soil variables. CONCLUSIONS: Overall, these fi ndings suggest that altitudinal gradients in herbivory and defenses in Q. robur are uncoupled and that elevational variation in herbivory and plant traits responds mainly to abiotic factors.

Article

BIOLOGÍA Y QUÍMICA MEDICINA Y CIENCIAS DE LA SALUD Altitudinal gradient Climate Herbivory Phenolics Plant traits Soil variables Spain

Olfactory Response and Host Plant Feeding of the Central American Locust Schistocerca piceifrons piceifrons Walker to Common Plants in a Gregarious Zone

ESAU RUIZ SANCHEZ (2016)

The Central American locust (CAL) Schistocerca piceifrons piceifrons Walker is one of the most harmful plant pests in the Yucatan Peninsula, where an important gregarious zone is located. The olfactory response and host plant acceptance by the CAL have not been studied in detail thus far. In this work, the olfactory response of the CAL to odor of various plant species was evaluated using an olfactometer test system. In addition, the host plant acceptance was assessed by the consumption of leaf area. Results showed that the CAL was highly attracted to odor of Pisonia aculeata. Evaluation of host plant acceptance showed that the CAL fed on Leucaena glauca and Waltheria americana, but not on P. aculeata or Guazuma ulmifolia. Analysis of leaf thickness, and leaf content of nitrogen (N) and carbon (C) showed that the CAL was attracted to plant species with low leaf C content.

Article

HOST SELECTION  INSECT–PLANT INTERACTION  LEAF TRAITS  OLFACTOMETER  BIOLOGÍA Y QUÍMICA

Diversidad morfológica y potencial productivo de variedades nativas de chile "poblano"

ROCIO TOLEDO AGUILAR (2010)

Tesis (Maestría en Ciencias, Especialista en Estrategias para el Desarrollo Agrícola Regional).- Colegio de Postgraduados, 2010

El chile (Capsicum spp.) como recurso fitogenético y por su gran diversidad de usos, tiene importancia económica, alimenticia y cultural. En Puebla, el chile “poblano” (Capsicum annuum L.) constituye una fuente de alimento así como de ingresos para las familias rurales de la región de la Sierra Nevada; sin embargo, se ha observado una disminución de los rendimientos, de la superficie sembrada y de los agricultores dedicados a este cultivo, a causa de factores como heladas, plagas y enfermedades, lo que puede llevar a pérdida de diversidad. A pesar de lo anterior, los estudios relacionados con variabilidad genética y problemática de producción de los tipos cultivados, incluyendo al chile poblano, son escasos. En este contexto, el objetivo de este estudio fue caracterizar la diversidad morfológica, agronómica y potencial productivo de un conjunto de 43 variedades criollas de chile poblano de la región antes mencionada y seis variedades introducidas, evaluándose en un diseño experimental látice triple 7×7, en dos localidades. Se realizó análisis de varianza combinado a 79 variables morfológicas, encontrándose diferencias significativas y altamente significativas entre genotipos en 47 de las variables analizadas. También se realizó análisis de componentes principales observándose que las variedades criollas de la región formaron un agrupamiento diferenciado y separándose de las introducidas; adicionalmente se realizó análisis de conglomerados, en el que se definieron cuatro subgrupos de variedades criollas de chile poblano, sin tener una relación con el lugar geográfico de colecta. Se seleccionó además por rendimiento el 20 % superior de las variedades, cuyos rendimientos de fruto fresco fluctuaron entre 7.4 y 9.6 t ha-1. Se encontró alta variabilidad en las poblaciones nativas, lo que proporciona elementos para diseñar programas de conservación, selección de variedades y mejora de la diversidad morfológica de chile poblano en la Sierra Nevada de Puebla. ______________ MORPHOLOGICAL DIVERSITY AND YIELD POTENTIAL OF “POBLANO” PEPPER LANDRACES. ABSTRACT: Chili pepper (Capsicum spp.) has economic, nutritional and cultural importance as plant genetic resource, as well as a variety of uses. In Puebla, “poblano” pepper (Capsicum annuum L.) represents a source of income and food for rural families in the region of the Sierra Nevada; however, recent records show lower yields, diminished area planted, and farmers growing this crop, due to the incidence of factors such as frosts, pests, diseases, among others, which can lead to loss of diversity. Despite the aforementioned, few studies related to genetic variability and problems in production of cultivated types, including poblano pepper have been carried out. In this context, the objective of this study was to characterize the morphological and agronomic as well as the yield potential of a group of 43 poblano pepper landraces of the region mentioned above, and 6 introduced varieties, evaluating theme under a 7 x 7 triple lattice experimental design in two localities. 79 Traits were registered and submitted to analysis of variance founding significant differences between genotypes in 47 of the analyzed traits. A principal components analysis was conducted, and results showed that native landraces formed a group, separated from those introduced; in addition, a cluster analysis was performed, identifying four subgroups of poblano pepper landraces, without a relation to the provenance site. Twenty percent of the varieties was selected on the basis of fresh fruit yield ranging from 7.4 to 9.6 t ha-1. High variability was found among native populations, which provides elements for designing a conservation program, selection of improved varieties and improvement of morphological diversity of poblano pepper in the Sierra Nevada, state of Puebla.

Master thesis

Capsicum annuum L. Diversidad morfológica Puebla, México Rendimiento Variables morfológicas Variedades nativas Morphological diversity Yield Morphological traits Native landraces Maestría Estrategias para el Desarrollo Agrícola Regional CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Molecular mapping across three populations reveals a QTL hotspot region on chromosome 3 for secondary traits associated with drought tolerance in tropical maize

Sudha Nair Aluizio Borem Jill Cairns Samuel Trachsel jean-marcel ribaut Marianne Bänziger Prasanna Boddupalli Jose Crossa Raman Babu (2014)

Identifying quantitative trait loci (qtl) of sizeable effects that are expressed in diverse genetic backgrounds across contrasting water regimes particularly for secondary traits can significantly complement the conventional drought tolerance breeding efforts. We evaluated three tropical maize biparental populations under water-stressed and well-watered regimes for drought-related morpho-physiological traits, such as anthesis-silking interval (asi), ears per plant (epp), stay-green (sg) and plant-to-ear height ratio (peh). In general, drought stress reduced the genetic variance of grain yield (gy), while that of morpho-physiological traits remained stable or even increased under drought conditions. We detected consistent genomic regions across different genetic backgrounds that could be target regions for marker-assisted introgression for drought tolerance in maize. A total of 203 qtl for asi, epp, sg and peh were identified under both the water regimes. Meta-qtl analysis across the three populations identified six constitutive genomic regions with a minimum of two overlapping traits. Clusters of qtl were observed on chromosomes 1.06, 3.06, 4.09, 5.05, 7.03 and 10.04/06. Interestingly, a ~8-mb region delimited in 3.06 harboured qtl for most of the morpho-physiological traits considered in the current study. This region contained two important candidate genes viz., zmm16 (mads-domain transcription factor) and psbs1(photosystem ii unit) that are responsible for reproductive organ development and photosynthate accumulation, respectively. The genomic regions identified in this study partially explained the association of secondary traits with gy. Flanking single nucleotide polymorphism markers reported herein may be useful in marker-assisted introgression of drought tolerance in tropical maize.

Article

Secondary traits |MetaQTL Drought tolerance SNP CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Combined effect of water potential and temperature on seed germination and seedling development of cacti from a mesic Argentine ecosystem

Diego E. Gurvich Reyes Manuel Pérez Sánchez karen bauk ENRIQUE JURADO YBARRA Maria Cecilia Ferrero Guillermo Funes Joel David Flores Rivas (2017)

"Global climatic change will be associated with an increase of droughts and heat waves, which can affect seed germination and plant population dynamics. Cactus species from mesic ecosystems are likely to be more affected by these events than species from arid ecosystems. The aim of the study was to assess the combined effect of water potentials and temperatures on seed germination and seedling traits in six globose cactus species from Córdoba Mountains: Echinopsis candicans, Gymnocalycium bruchii, G. capillense, G. mostii, G. quehlianum and Parodia mammulosa. A factorial experiment was performed in which four water potential levels (0, ?0.2, ?0.4 and ?0.6 MPa) were combined with two temperature levels (25 and 32 °C). Germination (%) and mean germination time (T50) were recorded and seedling shape (width and length) was measured. In general, a decrease in water potential and an increase in temperature resulted in low germination, with different behaviors among species. At 32 °C and low water potentials, germination was low or null for almost all species. There was not a clear trend in the response of T50 to the treatments. Seedling development was highly and negatively affected by the combination of factors, particularly at low water potentials. The responses of the analyzed cactus species to low water potential were similar to those of cactus species from more arid ecosystems. Our results suggest that the studied species would be severely affected by changes in temperature and precipitation as predicted under a climate change scenario."

Article

Climate change Germination characteristics Seedling traits Cactaceae Córdoba Mountains INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS INGENIERÍA Y TECNOLOGÍA DEL MEDIO AMBIENTE INGENIERÍA Y TECNOLOGÍA DEL MEDIO AMBIENTE

Taxco, Guerrero: historical facts, daily life and daily routine, tourist places and important festivals.

ADRIAN URIOSTEGUI FLORES (2016)

In this paper we study and investigates 1) the historical facts, 2) daily life and daily routine, 3) tourist sites and 4) the important festivals of the city of Taxco, Guerrero.

Article

Tourism Anthropology cultural traits MEDICINA Y CIENCIAS DE LA SALUD CIENCIAS MÉDICAS OTRAS ESPECIALIDADES MÉDICAS CIENCIAS SOCIALES GEOGRAFÍA OTRAS ESPECIALIDADES GEOGRÁFICAS