Author: CLAUDIA GONZALEZ SALVATIERRA

Respuestas fisiológicas y morfológicas a sequía en plántulas de distintos grupos funcionales del desierto chihuahuense

CLAUDIA GONZALEZ SALVATIERRA (2005)

"Las plantas de zonas áridas muestran una extraordinaria plasticidad en los procesos morfológicos y fisiológicos en respuesta a las variaciones del ambiente abiótico. Algunas adaptaciones de las plantas a condiciones adversas como la sequía, pueden ser la acumulación de osmolitos orgánicos y/o de solutos involucrados en el ajuste osmótico. Un aminoácido sensible a estrés por sequía es la prolina. Aunque poco estudiado, la capacidad de acumulación de prolina puede ser un mecanismo bioquímico clave para el establecimiento de plántulas en zonas áridas. En este trabajo, se plantea determinar la capacidad de algunas plántulas de especies del desierto chihuahuense para producir prolina en sus tallos y raíces, y relacionarlo con modificaciones morfológicas bajo distintos niveles de humedad de suelo. Se trabajó con 16 especies de tres grupos funcionales: arbustos, gramíneas y suculentas. El experimento se realizó en invernadero. Se tuvieron dos tratamientos de humedad del suelo: riego (control) y un ciclo alternado de sequíariego (para determinar la plasticidad en la recuperación de las plántulas con el riego después de un tratamiento de sequía). Se utilizaron 4 especies para los arbustos, 4 especies para las gramíneas y 8 especies de suculentas; con 6 plántulas/especie por tratamiento. Se determinó la concentración de prolina en los tejidos de las plántulas en tres cosechas (días 0, 15 y 30). Se presentan diferencias entre los grupos funcionales en el contenido de prolina entre tratamientos de humedad, tanto en tallo como en raíz, lo que sugiere que la concentración de prolina es una adaptación a estrés hídrico y un mecanismo de supervivencia en la fase más critica del ciclo de vida de las especies del desierto. Las especies típicas del Altiplano muestran plasticidad en sus características morfológicas y fisiológicas a condiciones de sequía que facilitan su establecimiento en microhábitats con condiciones adversas."

Master thesis

Cactáceas Plántulas Sequias Grupos funcionales Prolina Zonas áridas Desierto Chihuahuense INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS INGENIERÍA Y TECNOLOGÍA DEL MEDIO AMBIENTE OTRAS

Microambiente lumínico y morfología y fisiología foliar de Bromelia karatas (Bromeliaceae) en una selva baja caducifolia de Yucatán, México

Light microenvironment and leaf morphology and physiology of Bromelia karatas (Bromeliaceae) in a tropical dry deciduous forest in Yucatán, Mexico

CLAUDIA GONZALEZ SALVATIERRA LUIS MANUEL PEÑA RODRIGUEZ CASANDRA REYES GARCIA (2013)

"El metabolismo ácido de las crasuláceas es una adaptación de algunas plantas a condiciones de escasez de agua o bióxido de carbono y está relacionado con mecanismos de respuesta anatómicos, morfológicos y fi siológicos para tolerar períodos prolongados de sequía. La luz puede afectar diferentes procesos metabólicos, fi siológicos y estructurales de las plantas cuando es excesiva, por lo que en ambientes cambiantes, como en las selvas caducifolias, las hojas presentan respuestas de fotoprotección. El objetivo de este trabajo fue determinar esas respuestas, en dos microambientes de luz y dos temporadas del año, en una bromeliácea terrestre (Bromelia karatas) de la selva baja caducifolia en el Parque Nacional Dzibilchaltún, Yucatán. Las características morfológicas y fi siológicas de las hojas refl ejaron la infl uencia del ambiente, lo que les permitió conservar potenciales hídricos diurnos elevados y minimizar la pérdida de agua para mantener la fotosíntesis. Estas características, en conjunto con las espinas foliares y el crecimiento asexual de esta especie, pueden ayudar a explicar su alto valor de importancia ecológica en esta selva baja caducifolia."

"Crassulacean acid metabolism is an adaptation of certain plants to the lack of water or carbon dioxide and it is related to anatomical, morphological, and physiological response mechanisms to cope with long drought periods. High light can affect metabolic, physiological, and structural processes in plants and, in changing environments (such as those of a seasonally dry forests), plant leaves show anatomical and physiological photoprotection responses. The objective of this study was to determine those responses in two light microenvironments and in two seasons for a terrestrial bromeliad (Bromelia karata) from the tropical dry deciduous forest of Dzibilchaltún National Park in Yucatán, Mexico. The morphological characteristics of the leaves of B. karatas refl ected the infl uence of the environmental factors and allowed maintaining high diurnal water potentials and diminishing water loss to maintain photosynthesis. These foliar characteristics, along with the foliar spines and asexual growth of this species, can help to explain its high ecological importance value in this tropical dry deciduous forest."

Article

Fluorescencia de la clorofila Fotoprotección Metabolismo ácido de las crasuláceas Potencial hídrico CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

Germinación, infestación y viabilidad en bellotas de Quercus polymorpha (Schltdl.

&

Cham.) tras un año de almacenamiento

Germination, infestation, and viability in acorns of Quercus polymorpha (Schltdl.

&

Cham.) after 1-year storage

CLAUDIA GONZALEZ SALVATIERRA ERNESTO IVAN BADANO JOEL DAVID FLORES RIVAS (2013)

"Los encinos blancos tienen semillas recalcitrantes que se mantienen viables por corto tiempo. Sin embargo, esta información es escasa para encinos mexicanos. Este es el caso de Quercus polymorpha, una especie tolerante a la sequía y ampliamente distribuida en la Sierra Madre Oriental que puede utilizarse en programas de restauración forestal. Las bellotas son colectadas durante la época reproductiva y son almacenadas por varios meses antes de su germinación. Este estudio se enfocó en 1) determinar cuántas semillas se pierden durante el almacenamiento debido a factores fisiológicos relacionados con su viabilidad, 2) cuantificar las semillas que se pierden por otros factores, y 3) evaluar si la estratificación fría puede estimular la germinación de las bellotas. Las bellotas utilizadas fueron almacenadas durante un año. El 70 % de las bellotas estaban parasitadas por insectos antes de su almacenamiento, mientras que el 20 % perdió su viabilidad debido a factores fisiológicos o infestación por hongos. Los ensayos de germinación se llevaron a cabo utilizando sólo bellotas potencialmente viables, las cuales fueron sometidas a tres periodos de estratificación en frío (0, 20 y 50 días). El experimento mostró que las bellotas estratificadas durante 50 días tienen mayores tasas de germinación (64.2 %) que las de 20 (44.8 %) y 0 días (16. 5 %)."

"White oaks have recalcitrant seeds that remain viable for short periods of time, but this information is still conspicuously lacking for Mexican oaks. This is the case of Quercus polymorpha, a drought-tolerant species widely distributed across Sierra Madre Oriental that can be used in forest restoration programs. The acorns used to develop their saplings are collected during the reproductive season and stored by several months before their germination. This study focused in 1) determining how many seeds are lost during storage because of physiological factors linked to their viability, 2) quantifying how many seeds were lost by other factors, and 3) assessing whether cold stratification can stimulate acorn germination. Acorns used in this study were stored during a round year. We found that 70 % of these acorns were parasitized by insects prior to their storage, while an additional 20 % had lost their viability due to physiological factors or fungal infestation. Germination trials were performed by only using potentially viable acorns, which were subjected to three different cold stratification periods (0, 20 and 50 days). This experiment indicated acorns stratified during 50 days display higher germination rates (64.2 %) than those stratified by 20 (44.8 %) and 0 days (16.5 %)."

Article

Estratificación en frío Parasitismo de semillas Insectos Hongos Pruebas de viabilidad CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS AGRONOMÍA AGRICULTURA, SILVICULTURA, PESCA

Growth and ecophysiology of succulent seedlings under the protection of nurse plants in the Southern Chihuahuan Desert

REYES MANUEL PEREZ SANCHEZ JOEL DAVID FLORES RIVAS Enrique Jurado CLAUDIA GONZALEZ SALVATIERRA (2015)

"In arid zones, light and water are two important factors that limit seedling development. The shade provided by nurse plants can reduce overheating, excessive transpiration, and photoinhibition in protege seedlings. The difference that a nurse plant microenvironment may provide on the physiological performance of succulent desert seedlings could be tested by measuring plant growth and photosynthesis. Specifically, in this study we measured the variables related to chlorophyll fluorescence: Quantum yield of photosystem II photochemistry (UPSII) and electron transport rate (ETR), as well as relative growth rate (RGR) and its components (net assimilation rate, NAR, and leaf area rate, LAR), root to shoot (R/S) ratio, and relative water content (RWC) for seedlings transplanted under nurse plants and seedlings transplanted under direct sunlight. We tested whether UPSII, ETR, LAR, R/S ratio, and RWC, were lower, and RGR and NAR were higher for seedlings of seven succulent species common to the Southern Chihuahuan Desert (Agave lechuguilla, A. salmiana, Echinocactus platyacanthus, Ferocactus histrix, Myrtillocactus geometrizans, Stenocactus coptonogonus and Yucca filifera) grown under direct sunlight than for those grown under nurse Mesquite trees. Although species responded differently to treatments, in general we found that seedlings grown under nurse plants had higher UPSII and lower ETR than those grown under direct sunlight. RWC, R/S ratio, and RGR and its components varied in response to microenvironments for some species but not consistently. The ecophysiology variables tested here were more clearly affected by solar radiation than the morphology variables. These results are the first field study including the ecophysiological and morphological mechanisms of seedlings of succulent species under nurse plants."

Article

Asparagaceae Cactaceae, Mimosaceae Nurse-protégé Seedling ecophysiology Seedling growth Southern Chihuahuan Desert CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA

High tolerance to high-light conditions for the protected species Ariocarpus kotschoubeyanus (Cactaceae)

ERIKA ARROYO PEREZ JOEL DAVID FLORES RIVAS CLAUDIA GONZALEZ SALVATIERRA MARIA LORAINE MATIAS PALAFOX CECILIA LEONOR JIMÉNEZ SIERRA (2017)

"We determined the seasonal ecophysiological performance under perennial plants and under high solar radiation for adult individuals from the ‘living rock’ cactus Ariocarpus kotschoubeyanus, which occurs equally under nurse plants and in open spaces. We evaluated the effective quantum yield of photosystem II (ΦPSII) and the dissipation of thermal energy [non-photochemical quenching (NPQ)] thorough the year. The maximum apparent electron transport rate (ETRmax) and the saturating photosynthetically active photon flux density for PSII (PFDsat) were also determined from rapid light curves. We found that although the ΦPSII was higher in shaded sites under potential nurse plants than in exposed sites, all values were close to the optimal value of 0.83. The high ΦPSII found for A. kotschoubeyanus plants suggests that they use a great proportion of the absorbed light for photosynthesis, under nurse plants as well as in open spaces. We also found higher NPQ values in exposed sites than in shaded ones but only in Autumn, thus reducing the risk of photoinhibition. In addition, the PFDsat was higher in exposed sites than in shaded ones in Spring, Summer and Autumn, but in Winter there were no differences between treatments. We also found high saturating light levels for ETR (PFDsat higher than 1378 μmol m−2 s−1) in all seasons but in winter for shaded and non-shaded plants. Our findings indicate that A. kotschoubeyanus plants use a great proportion of the light that they absorb for photosynthesis. This high tolerance to high-light conditions could explain why A. kotschoubeyanus do not show preferences for protected sites under nurse plants."

Article

Chihuahuan desert Chlorophyll fluorescence Endangered species Living rock cactus Nurse plants Stress tolerance CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA CIENCIAS AGRARIAS AGRONOMÍA ECOLOGÍA VEGETAL

Induced climate change impairs photosynthetic performance in Echinocactus platyacanthus, an especially protected Mexican cactus species

José Luis Aragón Gastelum Joel David Flores Rivas LAURA YAÑEZ ESPINOSA ERNESTO IVAN BADANO Hugo Magdaleno Ramírez Tobias Juan Pablo Rodas Ortíz CLAUDIA GONZALEZ SALVATIERRA (2014)

"The responses of desert plants to climate warming have been poorly assessed, perhaps due to the overall expectation that desert vegetation will expand as a consequence of this component of climate change. However, determining what plant species will tolerate the expected increase in temperature is a question that remains unanswered. The Chihuahuan Desert is the largest warm desert of North America, and predictive models of climate change indicate that summer temperatures in this desert will increase by 1–2 °C in the next decade. This study experimentally assessed the performance of an endangered cacti species from the Chihuahuan Desert under simulated warming conditions. Hexagonal open top-chambers (OTCs) were used to simulate the effects of global warming on five-years-old individuals of the specially protected species Echinocactus platyacanthus. Temperature was 1.9 °C higher in open top-chambers than in control plots. In contrast, relative humidity was 3.1% higher in control plots than in open top-chambers. E. platyacanthus showed 100% survival for 14 weeks in both OTC and control plots. However, induced warming negatively affected the photosynthetic performance of this species. Cacti located within OTCs displayed lower maximum quantum efficiency of photosystem II (Fv/Fm), effective quantum yield of photosystem II (?PSII), and electron transport rate (ETR) values, but higher non-photochemical quenching (NPQ) values, than cacti from control plots. This is the first study focused on the potential impact of climate warming on survival and photosynthetic performance of young individuals of a succulent species from American deserts. Induced warming negatively affected the photosynthetic performance of young E. platyacanthus, but it also increased non-photochemical quenching, a mechanism for avoiding photoinhibition."

Article

Cactaceae Global warming Chlorophyll fluorescence Stress tolerance INGENIERÍA Y TECNOLOGÍA CIENCIAS TECNOLÓGICAS INGENIERÍA Y TECNOLOGÍA DEL MEDIO AMBIENTE INGENIERÍA Y TECNOLOGÍA DEL MEDIO AMBIENTE