Los bancos de semillas y su germinación en ambientes semiáridos

RESUMEN Los bancos de semillas son indispensables en ambientes semiáridos por ser la vía principal de regeneración para las comunidades vegetales en estos ecosistemas. El banco de semillas y sus características de regeneración varían entre las especies. Indistintamente, los cúmulos de semillas responden a las variaciones y al impacto de las precipitaciones pluviales que se presentan en cada sitio. Esto permite que las especies respondan de manera particular con estrategias, estructuras y periodos discontinuos de germinación para asegurar la persistencia de sus poblaciones en ambientes extremos. La evaluación de los bancos de semillas es primordial para el manejo y recuperación de sitios alterados. ABSTRACT Seed banks are fundamental in semiarid environments because they are the main path of regeneration for plant communities in these ecosystems. Seed banks and their characteristics of regeneration vary for each species. Seeds respond to the temperature and rainfall variations that occur in each ecosystem. Species respond with individual strategies, structures and intermittent periods of germination to assure population persistence in extreme environments. Evaluation of seed banks is important for management and restoration of disturbed sites

Ef fect of rhizobacteria isolated from Suaeda sp. in the growth of Arabidopsis thaliana and Solanum lycopersicum L. (Sahariana)

The rhizosphere of the great diversity of plants is a complex ecosystem that houses thousands of rhizobacteria that promote plant growth. In the current investigation, three bacteria were isolated from the root of Suaeda sp., which were evaluated to determine the ef fect of their inoculation on Arabidopsis thaliana at distances of 2 and 5 cm and in divided boxes. In the 2 cm test, we noticed that Endo10(7) and Endo10(5) stimulated the plants more than the control, while the proximity to Ecto10(6) caused them to wilt and die. However, at 5 cm, the bacterium that most promoted the development of Arabidopsis was Ecto10(6). In the divided box test, all three bacteria showed the ability to promote growth. In addition, a shade mesh assay was carried out with the inoculation of the bacteria in Solanum lycopersicum L. (Sahariana) and it was found that the promoting ef fect was also observed in the germination and growth of tomato plants. Tests were conducted to determine its ability to produce IAA, siderophores, and solubilize phosphates. Through molecular techniques it was confirmed: the identity of Ecto10(6), Endo10(7), and Endo10(5) as Aneurinibacillus migulanus, Staphylococcus sp. and Bacillus cereus, respectively. Our results provide the rationale for suggesting that these rhizobacteria may increase the growth and development of Arabidopsis thaliana and Solanum lycopersicum

Hidrocoria en semillas de Agave victoriae-reginae T. Moore, especie en peligro de extinción: Morfología y anatomía como facilitadores de la hidro-dispersión y germinación

Agave victoriae-reginae is an endemic species from Chihuahuan Desert which grows on canyon walls. It has flattened seeds that can be dispersed during episodic flood events. This study was focused on examining possible morphological and anatomical adaptations which promote seed hydro-dispersion. A morphological and anatomical seed analysis by scanning electron microscopy (SEM) was performed. Aspects of permeability, flotation, germination and germination rate (T50) for treatment and seed sizes were evaluated. The seeds are different in length, diameter, thickness, but not in weight; lacryform semi-flat shape and covered with porous air chambers in the hypodermis and were considered neutral photoblastic. We conclude that seeds of A. victoriae-reginae have hydro-dispersion characteristics.Agave victoriae-reginae es una especie endémica del Desierto Chihuahuense y crece sobre paredes en cañones. Posee semillas aplanadas que pueden ser dispersadas durante eventos episódicos de inundación. La presente investigación se basó en determinar posibles adaptaciones morfológicas y anatómicas en las semillas que favorecen la hidro-dispersión. Se realizó un análisis morfológico y anatómico de las semillas mediante microscopía electrónica de barrido (MEB). Se evaluaron aspectos de permeabilidad, fl otabilidad, germinación y velocidad de germinación (T50) por tratamientos y tamaños de semilla. Las semillas son diferentes en longitud, diámetro, espesor y no en peso; con forma lacriforme semiplanas y cubierta porosa con cámaras de aire en la hipodermis y son consideradas fotoblásticas neutras. Se concluye que las semillas de la especie poseen características propias para la hidro-dispersión

Influence of fetal bovine serum and amino acids on limb regeneration in the african clawed frog (Xenopus laevis)

La regeneración biológica es la capacidad que poseen ciertos organismos para restaurar algún tejido perdido o lesionado. Se han utilizado diversos modelos biológicos para el estudio de la regeneración como las hidras (Hydra viridis), las planarias (Planaria maculata, P. lugubris) y los anfibios (Ambystoma mexicanum, Xenopus laevis). En este trabajo se investigó la influencia del suero fetal bovino y aminoácidos en la regeneración de extremidades en la rana africana de uñas (Xenopus laevis). Se estudiaron 40 especímenes en estadio 66 a los cuales se les realizó una amputación en el área proximal de la tibia-peroné de la extremidad posterior derecha, formando cinco grupos (tratamientos) (aminoácidos, suero fetal bovino, solución fisiológica, estimulación mecánica y control) que estuvieron en fase experimental por un lapso de 78 días. Se realizaron análisis morfométricos y de mortalidad. Los resultados mostraron que no existe una diferencia significativa respecto al ancho y largo de la espícula bajo la influencia de estos tratamientos. La mortalidad fue mayor en el grupo donde se aplicó suero fetal bovino y menor en el grupo que recibió aminoácidos. Probablemente la capacidad regenerativa en el estadio 66 está más influida por el sitio de amputación que por los tratamientos.Biological regeneration is the capacity that certain organisms have to restore any lost or injured tissue. Regeneration has been studied in diverse biological models, for example the hydra (Hydra viridis), planarian (Planaria maculata, P. lugubris), and amphibians (Ambystoma mexicanum, Xenopus laevis). In this work, the influence of fetal bovine serum and amino acids in limb regeneration in African clawed frog (Xenopus laevis) was investigated. Forty specimens were studied on stage 66 which underwent an amputation in the proximal tibia-fibula area of the right hind limb, forming five groups (treatments) (amino acids, fetal bovine serum, application of physiological serum, mechanical stimulation and control) that were in experimental phase for a period of 78 days. Mortality and morphometric analysis were performed. The results showed no significant difference from the width and length of the spike under the influence of these treatments. Mortality was higher in the group where fetal bovine serum was applied and lower in the group receiving amino acids. It is believed that the regenerative capacity in the stage 66 is more influenced by the amputation site than the treatments.Sociedad de Ciencias Morfológicas de La Plat

Influencia de suero fetal bovino y aminoácidos en la regeneración de extremidades en la rana africana de uñas (xenopus laevis)

Biological regeneration is the capacity that certain organisms have to restore any lost or injured tissue. Regeneration has been studied in diverse biological models, for example the hydra (Hydra viridis), planarian (Planaria maculata, P. lugubris), and amphibians (Ambystoma mexicanum, Xenopus laevis). In this work, the influence of fetal bovine serum and amino acids in limb regeneration in African clawed frog (Xenopus laevis) was investigated. Forty specimens were studied on stage 66 which underwent an amputation in the proximal tibia-fibula area of the right hind limb, forming five groups (treatments) (amino acids, fetal bovine serum, application of physiological serum, mechanical stimulation and control) that were in experimental phase for a period of 78 days. Mortality and morphometric analysis were performed. The results showed no significant difference from the width and length of the spike under the influence of these treatments. Mortality was higher in the group where fetal bovine serum was applied and lower in the group receiving amino acids. It is believed that the regenerative capacity in the stage 66 is more influenced by the amputation site than the treatments.La regeneración biológica es la capacidad que poseen ciertos organismos para restaurar algún tejido perdido o lesionado. Se han utilizado diversos modelos biológicos para el estudio de la regeneración como las hidras (Hydra viridis), las planarias (Planaria maculata, P. lugubris) y los anfibios (Ambystoma mexicanum, Xenopus laevis). En este trabajo se investigó la influencia del suero fetal bovino y aminoácidos en la regeneración de extremidades en la rana africana de uñas (Xenopus laevis). Se estudiaron 40 especímenes en estadio 66 a los cuales se les realizó una amputación en el área proximal de la tibia-peroné de la extremidad posterior derecha, formando cinco grupos (tratamientos) (aminoácidos, suero fetal bovino, solución fisiológica, estimulación mecánica y control) que estuvieron en fase experimental por un lapso de 78 días. Se realizaron análisis morfométricos y de mortalidad. Los resultados mostraron que no existe una diferencia significativa respecto al ancho y largo de la espícula bajo la influencia de estos tratamientos. La mortalidad fue mayor en el grupo donde se aplicó suero fetal bovino y menor en el grupo que recibió aminoácidos. Probablemente la capacidad regenerativa en el estadio 66 está más influida por el sitio de amputación que por los tratamientos

Rhizobacteria inoculation and its effect on the productive parameters of sorghum

Objective: To evaluate the effect of the Bacillus megaterium and Pseudomonas japonica rhizobacteria on the productive parameters of sorghum. Design/Methodology/Approach: The experiment was carried out in Padilla, Tamaulipas, where the effect of inoculating a sorghum crop with the Bacillus megaterium KN13 and Pseudomonas japonica KC14 strains on its productive parameters was evaluated. Both strains were used in two concentrations (106 and 107 CFU). A randomized block design was applied, consisting of five treatments (two strains × two concentrations, plus a control), with six and nine replications. Results: The B. megaterium and P. japonica strains can fix nitrogen and produce siderophores. Inoculating these strains into the sorghum crop increases grain yield, plant height, panicle length, plant stem diameter, and aerial dry weight. Better results are recorded when the strains have a 107 CFU concentration. Study Limitations/Implications: Each type of soil and crop has various microbiomes. Findings/Conclusions: The use of an adequate concentration of rhizobacteria improves sorghum production; therefore, it is a sustainable alternative, both for the nutrition of the crop and the reduction of the use of synthetic fertilizers