Weak crassulacean acid metabolism and other xerophytic adaptive traits in the genus Beaucarnea Lem. (Asparagaceae).

The genus Beaucarnea (Asparagaceae) has economic value as an ornamental plant but also has ecological importance. Nonetheless, habitat, physiological traits and growth parameters of this genus remain largely unknown. We characterized the environmental ranges of Beaucarnea inermis, B. gracilis and B. pliabilis; and screened for the presence of physiological adaptations to drought (biomass allocation, presence of crassulacean acid metabolism [CAM] and its effect on plant water use). We performed experiments in 3- and 5-year-old nursery-grown plants of the three species, measured dry mass accumulation in leaves/stems/roots and screened for CAM using gas exchange, titratable acidity and δ13 C. We performed a second experiment on the water and light use responses of B. pliabilis under drought treatment. We found that B. gracilis was limited to xerophytic scrubs (precipitation >400 mm yr-1 ), while B. pliabilis and B. inermis (precipitation >500 and 700 mm year-1 , respectively) inhabited dry forests. Beaucarnea gracilis had the lowest dry mass and allocation to leaves, while B. inermis showed the opposite pattern. Only B. pliabilis exhibited small but significant acid fluctuations, characterized as weak CAM, along with high proline content. Acid concentration contributed in 2.7% of the daily carbon during the wet season but represented most of the carbon in the dry season, under closed stomata and had an important contribution to osmolality. Thus, CAM is described for the first time in the genus Beaucarnea, but was only present in one of three species, warranting exploration of this metabolism in the remaining species of this genus.

Understanding the physiological responses of a tropical crop (Capsicum chinense Jacq.) at high temperature.

Temperature is one of the main environmental factors involved in global warming and has been found to have a direct effect on plants. However, few studies have investigated the effect of higher temperature on tropical crops. We therefore performed an experiment with a tropical crop of Habanero pepper (Capsicum Chinense Jacq.). Three growth chambers were used, each with 30 Habanero pepper plants. Chambers were maintained at a diurnal maximum air temperature (DMT) of 30 (chamber 1), 35 (chamber 2) and 40°C (chamber 3). Each contained plants from seedling to fruiting stage. Physiological response to variation in DMT was evaluated for each stage over the course of five months. The results showed that both leaf area and dry mass of Habanero pepper plants did not exhibit significant differences in juvenile and flowering phenophases. However, in the fruiting stage, the leaf area and dry mass of plants grown at 40°C DMT were 51 and 58% lower than plants at 30°C DMT respectively. Meanwhile, an increase in diurnal air temperature raised both stomatal conductance and transpiration rate, causing an increase in temperature deficit (air temperature - leaf temperature). Thus, leaf temperature decreased by 5°C, allowing a higher CO2 assimilation rate in plants at diurnal maximum air temperature (40°C). However, in CO2 measurements when leaf temperature was set at 40°C, physiological parameters decreased due to an increase in stomatal limitation. We conclude that the thermal optimum range in a tropical crop such as Habanero pepper is between 30 and 35°C (leaf temperature, not air temperature). In this range, gas exchange through stomata is probably optimal. Also, the air temperature-leaf temperature relationship helps to explain how temperature keeps the major physiological processes of Habanero pepper healthy under experimental conditions.

Enrichment of carbon dioxide in the atmosphere increases the capsaicinoids content in Habanero peppers (Capsicum chinense Jacq.).

BACKGROUND: The effects of the increase of atmospheric CO2 on agricultural productivity have been mainly analyzed through its impact on biomass yield, and little attention has been directed to quality traits, such as nutritional or organoleptic attributes. For this study, plants of hot Habanero pepper (Capsicum chinense Jacq.) were grown in growth chambers under three different CO2 levels: 380 (normal atmospheric value), 760 and 1140 µmol mol(-1), and their effects on pod yield, size, color and pungency, were monitored. RESULTS: The total number of pods per plant increased by 88.5% at the highest CO2 , in comparison to plants grown at normal CO2 conditions. Pod size and yield per plant also increased when plants were grown at the highest CO2 concentration (partial pressure). Furthermore, total capsaicinoids contents in ripe peppers under a high CO2 atmosphere were 27% higher than those from plants under lower concentrations, but it was not the case for immature pods. CONCLUSION: These data suggest that the increase of atmospheric CO2 could modify specific routes of secondary metabolism as well as others desirable traits, thus affecting the quality of Capsicum pepper products.

Arbuscular mycorrhizal propagules in soils from a tropical forest and an abandoned cornfield in Quintana Roo, Mexico: visual comparison of most-probable-number estimates.

The present study was aimed at comparing the number of arbuscular mycorrhizal fungi (AMF) propagules found in soil from a mature tropical forest and that found in an abandoned cornfield in Noh-Bec Quintana Roo, Mexico, during three seasons. Agricultural practices can dramatically reduce the availability and viability of AMF propagules, and in this way delay the regeneration of tropical forests in abandoned agricultural areas. In addition, rainfall seasonality, which characterizes deciduous tropical forests, may strongly influence AMF propagules density. To compare AMF propagule numbers between sites and seasons (summer rainy, winter rainy and dry season), a "most probable number" (MPN) bioassay was conducted under greenhouse conditions employing Sorgum vulgare L. as host plant. Results showed an average value of 3.5 ± 0.41 propagules in 50 ml of soil for the mature forest while the abandoned cornfield had 15.4 ± 5.03 propagules in 50 ml of soil. Likelihood analysis showed no statistical differences in MPN of propagules between seasons within each site, or between sites, except for the summer rainy season for which soil from the abandoned cornfield had eight times as many propagules compared to soil from the mature forest site for this season. Propagules of arbuscular mycorrhizal fungi remained viable throughout the sampling seasons at both sites. Abandoned areas resulting from traditional slash and burn agriculture practices involving maize did not show a lower number of AMF propagules, which should allow the establishment of mycotrophic plants thus maintaining the AMF inoculum potential in these soils.

Impactos del cambio climático en la floración y desarrollo del fruto del café en Veracruz, México / Impacts of climatic change on coffee flowering and fruit development in Veracruz, México / Impactos da mudança climática na floração e desenvolvimento do fruto do café em Veracruz, México

La región de Huatusco, Veracruz, es un área de alta producción de café en México. La temperatura y la precipitación son elementos climáticos a los que es sensible el cafeto. Estos parámetros están relacionados con la altitud, orientación de ladera y pendiente en los sistemas agroecológicos de sombra. Con la finalidad de tener un mejor conocimiento de los posibles impactos del cambio climático sobre la floración y desarrollo del fruto para las especies Coffea arabica y C. canephora, se realizó un escenario base, relacionando los períodos en los que estas fases reproductivas del cafeto se desarrollan con la climatología de la región a través de diagramas ombrotérmicos. Al diagrama ombrotérmico base, se le aplicaron los incrementos de temperatura y razones de cambio en precipitación de las salidas de dos modelos de cambio climático con el fin de medir para cada modelo los posibles impactos en las fases reproductivas señaladas. Según los dos escenarios de cambio climático aplicados, se pueden provocar diferencias importantes en la climatología regional y, por tanto, fuertes impactos, alterando el inicio de la floración que está relacionado con el promedio de lluvia mensual y la amplitud de la sequía preestival que se presenta durante los meses de invierno. Asimismo, el cambio climático impactaría sobre las variaciones en la disponibilidad de agua durante el crecimiento del fruto, relacionadas principalmente a modificaciones en el superávit hídrico y el incremento de la sequía intraestival que se presenta durante la estación lluviosa.

The region of Huatusco, in Veracruz, Mexico, is an area of high coffee production. Coffee trees are sensitive to temperature and precipitation variations. Those climatic elements are related to the altitude, aspect and slope in the agroecological shadow system. A baseline climatic scenario was introduced on ombrothermic diagrams to relate the periods in which the reproductive phases of the coffee tree develops with the climatology of the region. This method was developed in order to achieve a better knowledge of the possible impacts of climate change on the flowering and fruit development in the species Coffea arabica and C. Canephora. Increases of temperature and changes in precipitation were obtained using the outputs of two general circulation models, and applied to the basic ombrothermic diagram, in order to measure the possible impacts on the stated reproductive phases. According to those two climate change scenarios, important differences in regional climatology can be projected, and therefore strong impacts were detected: changes of the beginning of flowering which is related to the mean rainfall, and the extent of the preestival drought during the winter months. Also, climatic change could impact the water availability during the fruit growing period, which is related the modifications in water surplus and to the increase of the intraestival drought during the rainy season of the year.

A região de Huatusco, Veracruz, é uma área de alta produção de café no México. A temperatura e a precipitação são elementos climáticos aos quais o cafeeiro é sensível. Estes parâmetros estão relacionados com a altitude, orientação de ladeira e a pendente nos sistemas agroecológicos de sombra. Com a finalidade de ter um melhor conhecimiento dos posíveis impactos da mudança climática sobre a floração e desenvolvimento do fruto para as espécies Coffea arabica y C. canephora, se realizou um cenário base, relacionando os períodos em que estas fases reprodutivas do cafeeiro se desenvolvem com a climatologia da região através de diagramas ombrotérmicos. Ao diagrama ombrotérmico base, foram aplicados os incrementos de temperatura e padres de mudança em precipitação das saídas de dois modelos de mudança climática com o fim de medir, para cada modelo, os posíveis impactos nas fases reprodutivas apontadas. Segundo os dois cenários de mudança climática aplicados, podem ser provocadas diferências importantes na climatologia regional e, por tanto, fortes impactos, alterando o início da floração que está relacionado com a média de chuva mensal e a amplitude do veranico que se apresenta durante os meses de inverno. Da mesma forma, a mudança climática impactaria sobre as variações na disponibilidade de agua durante o crescimento do fruto, relacionadas principalmente a modificações no superávit hídrico e o incremento de veranicos que se apresentam durante a estação chuvosa.

Stem anatomical characteristics of the climbing palm Desmoncus orthacanthos (Arecaceae) under two natural growth conditions in a tropical forest

Desmoncus orthacanthos is a Neotropical climbing palm that resembles rattan and therefore has similar potential applications. The genus Desmoncus (subfamily Arecoideae, subtribe Bactridinae) is distributed throughout the Americas, from veracruz, Mexico, to Brazil and Bolivia. The anatomical characteristics of its support tissue have not been thoroughly studied, although some observations from Central American artisans suggest that the stems collected from undisturbed sites possess better characteristics; these include a good capacity to withstand bending without breaking (i.e. higher fracture strength than plants from disturbed sites). Stem samples were collected from individuals from disturbed and undisturbed sites, at three points along the length of the stem (basal, medium and apical). Collections were made of one ramet from five individuals (n=5) at both sites. Each ramet was divided into three sections: basal, from soil surface to a height of 0.5 m; medium, from a height of 0.5 to 5.0 m; and apical, from a height 5.0 to 10.0 m. An anatomical analysis including vascular bundles, parenchyma elements and fibers was performed in the radial direction and also along the longitudinal direction of the stems. The amount of vascular bundles was greater for samples from undisturbed site stems; the amount of parenchyma cells differ between samples from both sites and the amount of fibers was greater for samples from disturbed site stems. The anatomical structural dimensions were smaller for samples from the undisturbed site stems. These findings partially confirm the artisans’ belief and supports the conclusion that microclimatic conditions affect plant anatomical structure. Rev. Biol. Trop. 56 (2): 937-949. Epub 2008 June 30.

Desmoncus orthacanthos es una palmera trepadora neotropical que puede, potencialmente, utilizarse en usos similares a los del ratán. El género Desmoncus (subfamilia Arecoideae, subtribu Bactridinae) se distribuye en América desde Veracruz, Mexico, hasta Brasil y Bolivia. Esta especie posee características anatómicas que no han sido ampliamente estudiadas pero observaciones hechas por artesanos centroamericanos sugieren que los tallos de sitios no perturbados por actividades humanas presentan mayor resistencia al doblado y menos tallos fracturados en el manejo. Las muestras de tallos fueron recolectadas de individuos que crecen en un sitio conservado y uno perturbado por actividades humanas, a tres alturas de la longitud del tallo (basal, media y apical). Se recolectó una rama de cada uno de cinco individuos (n=5) en ambos sitios. Cada rama fue dividida en tres secciones: basal, desde el nivel del suelo hasta los 0.5 m; medio, desde 0.5 a 5.0 m; y apical, desde 5.0 a 10.0 m. Se midió la cantidad por unidad de área y las dimensiones o tamaño (i.e. diámetro radial y diámetro perpendicular) de paquetes vasculares, células de parénquima y fibras. La cantidad de paquetes vasculares fue mayor en los tallos del sitio conservado, la cantidad de células de parénquima fue diferente entre sitios y la cantidad de fibras fue mayor en los tallos del sitio perturbado por actividades humanas. Estas características muestran cierta relación con los resultados mecánicos en otro estudio de los autores, los cuales confirman parcialmente las observaciones de los artesanos, lo que puede estar estrechamente relacionado con las características microclimáticas de los sitios de crecimiento.

Stem anatomical characteristics of the climbing palm Desmoncus orthacanthos (Arecaceae) under two natural growth conditions in a tropical forest.

Desmoncus orthacanthos is a Neotropical climbing palm that resembles rattan and therefore has similar potential applications. The genus Desmoncus (subfamily Arecoideae, subtribe Bactridinae) is distributed throughout the Americas, from Veracruz, Mexico, to Brazil and Bolivia. The anatomical characteristics of its support tissue have not been thoroughly studied, although some observations from Central American artisans suggest that the stems collected from undisturbed sites possess better characteristics; these include a good capacity to withstand bending without breaking (i.e., higher fracture strength than plants from disturbed sites). Stem samples were collected from individuals from disturbed and undisturbed sites, at three points along the length of the stem (basal, medium and apical). Collections were made of one ramet from five individuals (n=5) at both sites. Each ramet was divided into three sections: basal, from soil surface to a height of 0.5 m; medium, from a height of 0.5 to 5.0 m; and apical, from a height 5.0 to 10.0 m. An anatomical analysis including vascular bundles, parenchyma elements and fibers was performed in the radial direction and also along the longitudinal direction of the stems. The amount of vascular bundles was greater for samples from undisturbed site stems; the amount of parenchyma cells differ between samples from both sites and the amount of fibers was greater for samples from disturbed site stems. The anatomical structural dimensions were smaller for samples from the undisturbed site stems. These findings partially confirm the artisans' belief and supports the conclusion that microclimatic conditions affect plant anatomical structure.

Mycorrhizal dynamics and dependence of desmoncus orthacanthos maritus (arecaceae) a native palm of the Yucatan peninsula Mexico

Se realizaron observaciones en una parcela (milpa) abandonada de ocho años de edad y en una selva madura para determinar la dinámica estacional y la recuperación de una perturbación en la asociación micorrícica arbuscular (MA) presente en Desmoncus orthacanthos Martius. En una prueba de invernadero se evaluó la dependencia micorrícica relativa (RMD) de esta especie. En el campo se seleccionaron cuatro etapas de crecimiento en esta palmera y se monitoreó durante un año las raíces y el suelo rizosférico de cinco individuos de cada etapa de crecimiento. Se detectó una dinámica estacional, pero no diferencia en la actividad de la asociación comparando la milpa abandonada y la selva madura. No se encontró correlación, durante el período de estudio, entre la humedad del suelo, densidad de esporas por gramo de suelo y colonización de raíces. El porcentaje de colonización fue mayor en ambos sitios durante la etapa de lluvias, este porcentaje fue igual de elevado en una temporada de secas en la milpa abandonada. La densidad de esporas fue mayor en la temporada de secas. Los valores calculados de RMD se encuentran entre 7.8 y 54.9 por ciento por ciento, con una mayor biomasa en las plantas micorrizadas comparadas con las no-micorrizadas usando concentraciones de fósforo similares a las presentes en el suelo de los sitios de estudio. Los resultados sugieren que esta especie es dependiente de la asociación micorrícica en las condiciones evaluadas y mantiene una actividad de AM relativamente alta incluso durante la temporada de secas. Los resultados sugieren que las practicas agrícolas empleadas en la zona de estudio permiten la recuperación del potencial de inoculo del suelo para el crecimiento de D. orthacanthos

Establishment of Desmoncus orthacanthos Martius (Arecaceae): effect of inoculation with arbuscular mycorrhizae

Inoculation with arbuscular mycorrhizal (AM) fungi has often promoted increased growth of plants but very little work has been done in the tropics to evaluate the effects of inoculation on the establishment and development of seedlings in forests. Desmoncus orthacanthos Martius is a scandent palm present both in early and late succession, and consequently can be used in restoration processes. A test was conducted to determine the effect of AM on the establishment of Desmoncus orthacanthos in tropical forest in the Yucatan Peninsula, Mexico. Thirty inoculated and 30 non-inoculated seedlings were introduced in two sites of different successional age, a mature forest and an eight-year old abandoned cornfield (acahual).Survival and growth parameters were evaluated after 12 months. Leaf area and phosphorus, but not height, were greater in inoculated than non-inoculated plants in the forest but not in the acahual. However, mycorrhizae had a clear effect on plant survival in both sites, with a threefold increase in survival of inoculated compared with non-inoculated plants bassed on an odds ratio. The results suggest that inoculation will be important to increase the establishment of this commercially important palm.

La inoculación con hongos micorrizógenos arbusculares (AM)promueve un incremento en el crecimiento de las plantas, sin embargo poco trabajo se ha realizado en los trópicos para evaluar el efecto de la inoculación en el proceso de establecimiento de plántulas. Desmoncus orthacanthos Martius es una palmera trepadora que se distribuye tanto en etapas tempranas y tardías de la sucesión, por lo tanto puede ser empleada en procesos de restauración. Se realizó una prueba de establecimiento de D. orthacanthos en una selva tropical de la península de Yucatán, México. Treinta plántulas inoculadas y 30 no inoculadas se establecieron en dos sitios con diferentes etapas sucesionales: selva madura y un campo abandonado de maíz (acahual). Después de 12 meses el valor de área foliar y contenido de fósforo fue mayor en el tratamiento con micorrizas en la selva pero no en el acahual, sin embargo, el tratamiento con micorrizas mostró un claro efecto en la supervivencia de las palmeras en ambos sitios con un incremento tres veces mayor en la probabilidad de supervivencia de palmeras inoculadas comparadas con las no inoculadas de acuerdo al análisis de razón de disparidad (odds ratio). La inoculación podría ser importante para incrementar el establecimiento de esta palmera.

Establishment of Desmoncus orthacanthos Martius (Arecaceae): effect of inoculation with arbuscular mycorrhizae.

Inoculation with arbuscular mycorrhizal (AM) fungi has often promoted increased growth of plants but very little work has been done in the tropics to evaluate the effects of inoculation on the establishment and development of seedlings in forests. Desmoncus orthacanthos Martius is a scandent palm present both in early and late succession, and consequently can be used in restoration processes. A test was conducted to determine the effect of AM on the establishment of Desmoncus orthacanthos in tropical forest in the Yucatan Peninsula, Mexico. Thirty inoculated and 30 non-inoculated seedlings were introduced in two sites of different successional age, a mature forest and an eight-year old abandoned cornfield (acahual). Survival and growth parameters were evaluated after 12 months. Leaf area and phosphorus, but not height, were greater in inoculated than non-inoculated plants in the forest but not in the acahual. However, mycorrhizae had a clear effect on plant survival in both sites, with a threefold increase in survival of inoculated compared with non-inoculated plants bassed on an odds ratio. The results suggest that inoculation will be important to increase the establishment of this commercially important palm.

Polihidramnios: informe de un caso y manejo actual / Polyhydramnios: report of a case and present handling

El polihidramnio es una patología relativamente frecuente en obstetricia que puede complicar el embarazo según el grado de severidad. La mayoría de los casos no tienen una causa demostrable auque ahora con las nuevas técnicas de diagnóstico un porcentaje de ellos tienen afecciones genéticas. El tratamiento actual consta de fármacos junto a la amniocentesis con control ultrasonográfico. En el presente informe se describe un caso de polihidramnios severo en el cual no se demostró etiología y se manejó con indometacina y amniocentesis

Polihidramnios: informe de un caso y manejo actual / Polyhydramnios: report of a case and present handling

El polihidramnio es una patología relativamente frecuente en obstetricia que puede complicar el embarazo según el grado de severidad. La mayoría de los casos no tienen una causa demostrable auque ahora con las nuevas técnicas de diagnóstico un porcentaje de ellos tienen afecciones genéticas. El tratamiento actual consta de fármacos junto a la amniocentesis con control ultrasonográfico. En el presente informe se describe un caso de polihidramnios severo en el cual no se demostró etiología y se manejó con indometacina y amniocentesis

Mortalidad materna: estudio de tres años en el Hospital Materno Infantil / Maternal mortality: three years study at the Hospital Materno Infantil

El presente estudio fue realizado prospectivamente en el Hospital Materno Infantil del 1 de enero de 1994 al 31 de diciembre de 1995. Los datos revelan la mortalidad materna intrahospitalaria, los cuales son contradictorios a los publicados por el Ministerio de Salud Pública de 175 muertes maternas por cada 100,000 nacidos vivos y de 72.1 por 100,000 nacidos vivos en nuestro estudio; lo anterior refleja una dismunición de la mortalidad intrahospitalaria a pesar de que las fallas detectadas en el sistema de información estadística fueran grandes. Se analizó retrospectivamente la tasa de mortalidad materna (TMM) de 1993 de 72.6/100,000 (n=14) y prospectivamente, 1994: 107.6/100,000 (n=15). Las tres principales causas de mortalidad materna fueron: de índole infecciosa: 28.6 por ciento (n=10), Enfermedad Hipertensiva en el Embarazo (EHE) 34.2 por ciento (n=12) y SIDA 14.3 por ciento (n=5) La mortalidad obstétrica directa fue de 60 por ciento e indirecta de 40.0 por ciento, el 31.4 por ciento (n=11) se consideró evitable, probablemente evitable, 48.6 por ciento (n=17) y no evitable 20 por ciento (n=7). Se analizan los factores de riesgo reproductivo, obstétrico y responsabilidad médica-hospitalaria y materno-comunitaria.