Germinación y crecimiento de especies nativas potenciales para reforestación en el estado de Tabasco, México

La presente Tesis Doctoral tiene por objetivo contribuir al conocimiento de los procesos de producción de planta y de la reforestación forestal con especies nativas. Se muestran los resultados de los procesos de germinación de una especie en peligro de extinción (Ormosia macrocalyx), bajo dos experimentos independientes: 1) germinación de semillas obtenidas de frutos en tres etapas de maduración y 2) germinación de semillas almacenadas por 17 meses en condiciones de refrigeración, bajo tratamientos pregerminativos (control, escarificación mecánica, remojo por 24 horas y escarificación mecánica + Ácido giberélico al 1%). Además, se evaluó el crecimiento de seis especies nativas tropicales (Calophyllum brasiliense, Bravaisia integerrima, Dialium guianense, Piscidia piscipula, Tabebuia donnell-smithii y Enterolobium cyclocarpum), bajo 50% de sombra, las variables analizadas fueron: longitud de tallo, diámetro basal y tasas relativas de crecimiento durante seis meses. Paralelamente, se estableció un experimento en campo sobre un suelo arenoso para obtener el porcentaje de supervivencia y el crecimiento de cinco especies arbóreas (Tabebuia rosea, Enterolobium cyclocarpum, Gliricidia sepium, Ceiba pentandra y Brosimum alicastrum) en un diseño de bloques al azar. Las mediciones de la longitud de tallo y diámetro basal por 23 meses, sirvieron para obtener las tasas relativas de crecimiento y las áreas basimétricas.Departamento de Producción Vegetal y Recursos ForestalesDoctorado en Conservación y Uso Sostenible de Sistemas Forestale

Anatomía foliar de Malpighia mexicana (Malpighiaceae)

Background and Aims: Malpighia mexicana is a native tree widely distributed in Mexico, which is cultivated in orchards or backyards of rural areas, and source of economic, timber, ornamental and medicinal resources. Studies on foliar anatomy of the genus Malpighia are scarce; characters such as the shape, length, width and pubescence of the leaf are used to classify its species. As a consequence, the objectives of this study were to escribe the anatomical characteristics of the leaf of M. mexicana and to determine the structural characters that are influenced by the environment, in order to contribute to the taxonomic and ecoanatomical knowledge of the genus Malpighia in Mexico.Methods: Three individuals with similar height and coverage were selected in three sites; a sample composed of 20 leaves was obtained; the leaves were fixed in FAA, washed with water and processed by conventional anatomy techniques, ending with inclusion and infiltration in paraffin. Paradermal and transverse cuts were made (15-20 μm), photographs were taken, and measurements were recorded with the image analyzer Leica LV 40.Key results: The leaves of M. mexicana in paradermal section present polygonal and rectangular cells, in some cases ovate-rectangular, linear and thick anticlinal walls are hypoestomatic with paracitic stomatal complexes and present epidermal appendages with single and branched unicellular trichomes. Transversely the leaves consist of a simple unistratified epidermis and bifacial mesophyll. The development of adaptation strategies was observed in both mesic and xeric environments.Conclusions: The anatomical characters that allow to differentiate M. mexicana are the disposition and type of trichomes and type of stomata. Foliar anatomy presented correlated traits both with mesic (dorsiventral leaf, intercellular spaces in the mesophyll, absence of sclerenchyma) and xeric environments (epidermis of large cells, higher concentration of stomata in the abaxial surface).Antecedentes y Objetivos: Malpighia mexicana es un árbol nativo de México y ampliamente distribuido en el país. Se cultiva en huertos o traspatios de zonas rurales, es fuente de recursos económicos, maderables, ornamentales y medicinales. Los estudios sobre la anatomía foliar del género Malpighia son escasos; caracteres como la forma, longitud, ancho y pubescencia de la hoja se usan para clasificar sus especies. Debido a lo anterior, los objetivos de este estudio fueron describir las características anatómicas de la hoja de M. mexicana y determinar los caracteres estructurales que están influenciados por el ambiente, como una forma de contribuir al conocimiento taxonómico y ecoanatómico del género Malpighia en México.Métodos: Se seleccionaron tres individuos con altura y cobertura similar en tres sitios; se obtuvo una muestra compuesta de 20 hojas; las hojas se fijaron en FAA, se lavaron con agua corriente y se procesaron mediante técnicas de anatomía convencional, terminando con una inclusión e infiltración en parafina. Se realizaron cortes paradermales y transversales (15-20 µm), se tomaron fotografías y se registraron mediciones con el analizador de imágenes Leica LV 40.Resultados clave: Las hojas de M. mexicana en corte paradermal presentan células poligonales y rectangulares, en algunos casos ovado-rectangulares, paredes anticlinales lineales y gruesas, son hipoestomáticas con complejos estomáticos paracíticos y presentan apéndices epidérmicos con tricomas unicelulares simples y ramificados. Transversalmente, las hojas constan de una epidermis simple uniestratificada y mesófilo bifacial. Se observó el desarrollo de estrategias de adaptación tanto en ambientes mésicos como en ambientes xéricos.Conclusiones: Los caracteres anatómicos que distinguen a M. mexicana de otras especies de su género son la disposición y tipo de tricomas y estomas. La anatomía foliar presentó rasgos correlacionados tanto con ambientes mésicos (hoja dorsiventral, espacios intercelulares en el mesófilo, ausencia de esclerénquima) como con ambientes xéricos (epidermis de células grandes, mayor concentración de estomas en la superficie abaxial)

Albiglutide and cardiovascular outcomes in patients with type 2 diabetes and cardiovascular disease (Harmony Outcomes): a double-blind, randomised placebo-controlled trial

Background: Glucagon-like peptide 1 receptor agonists differ in chemical structure, duration of action, and in their effects on clinical outcomes. The cardiovascular effects of once-weekly albiglutide in type 2 diabetes are unknown. We aimed to determine the safety and efficacy of albiglutide in preventing cardiovascular death, myocardial infarction, or stroke. Methods: We did a double-blind, randomised, placebo-controlled trial in 610 sites across 28 countries. We randomly assigned patients aged 40 years and older with type 2 diabetes and cardiovascular disease (at a 1:1 ratio) to groups that either received a subcutaneous injection of albiglutide (30–50 mg, based on glycaemic response and tolerability) or of a matched volume of placebo once a week, in addition to their standard care. Investigators used an interactive voice or web response system to obtain treatment assignment, and patients and all study investigators were masked to their treatment allocation. We hypothesised that albiglutide would be non-inferior to placebo for the primary outcome of the first occurrence of cardiovascular death, myocardial infarction, or stroke, which was assessed in the intention-to-treat population. If non-inferiority was confirmed by an upper limit of the 95% CI for a hazard ratio of less than 1·30, closed testing for superiority was prespecified. This study is registered with ClinicalTrials.gov, number NCT02465515. Findings: Patients were screened between July 1, 2015, and Nov 24, 2016. 10 793 patients were screened and 9463 participants were enrolled and randomly assigned to groups: 4731 patients were assigned to receive albiglutide and 4732 patients to receive placebo. On Nov 8, 2017, it was determined that 611 primary endpoints and a median follow-up of at least 1·5 years had accrued, and participants returned for a final visit and discontinuation from study treatment; the last patient visit was on March 12, 2018. These 9463 patients, the intention-to-treat population, were evaluated for a median duration of 1·6 years and were assessed for the primary outcome. The primary composite outcome occurred in 338 (7%) of 4731 patients at an incidence rate of 4·6 events per 100 person-years in the albiglutide group and in 428 (9%) of 4732 patients at an incidence rate of 5·9 events per 100 person-years in the placebo group (hazard ratio 0·78, 95% CI 0·68–0·90), which indicated that albiglutide was superior to placebo (p<0·0001 for non-inferiority; p=0·0006 for superiority). The incidence of acute pancreatitis (ten patients in the albiglutide group and seven patients in the placebo group), pancreatic cancer (six patients in the albiglutide group and five patients in the placebo group), medullary thyroid carcinoma (zero patients in both groups), and other serious adverse events did not differ between the two groups. There were three (<1%) deaths in the placebo group that were assessed by investigators, who were masked to study drug assignment, to be treatment-related and two (<1%) deaths in the albiglutide group. Interpretation: In patients with type 2 diabetes and cardiovascular disease, albiglutide was superior to placebo with respect to major adverse cardiovascular events. Evidence-based glucagon-like peptide 1 receptor agonists should therefore be considered as part of a comprehensive strategy to reduce the risk of cardiovascular events in patients with type 2 diabetes. Funding: GlaxoSmithKline

Recurrent inconsistencies in publications that involve Maguire’s germination rate formula

Aim of study: The objective of this study was to present statistical information pertaining to recurrent inconsistencies found in the literature of the last 25 years that involve calculation of the GR and the errors that this may entail when interpreting the seed vigor of different botanical materials.Materiales y métodos: After filtering articles that did not present numerical results or in which the application of Maguire's formula was not clearly indicated, a total of 124 papers were ultimately used in this study.Main results: Germination rate (GR) represents the potential of seeds to germinate and, along with germination percentage (GP), are the two most important measurements when evaluating seed quality. The correct calculation of GR allows the seeds classification according to their vigor and capacity to produce healthy seedlings, so it is very important to rely on the adequate mathematical formula for this purpose. According to the formula developed by Maguire, this parameter is calculated by the sum of values obtained when dividing the GP at different times (i.e. daily) by the total time elapsed since the start of the test. We have found from the relevant literature that different authors have been using different ways of applying the formula, which makes it difficult to directly compare the results.Research highlights: A total of 54.8 % of the papers reviewed, belonging mainly to the theme of forestry, presented objectionable application of the formula. Publication of this warning may help to reduce the occurrence of this situation in the future.Keywords. Germination percentage, germination speed, Maguire’s formula, seed vigor

Germinación, crecimiento inicial y morfología de Castilla elastica (Moraceae) en Tabasco, México

Background and Aims:Castilla elastica is a Mesoamerican native species associated with different Prehispanic cultures that used their latex for ceremonial purposes. It is considered an emblematic tree, useful in agroforestry systems. This work aimed to evaluate the germination, initial growth and morphology of C. elastica.Methods: Seeds from 30 trees were collected and planted in polyethylene trays. The start of the germination was determined by the sprouting of the epicotyls. The percentage of germination was quantified, and three periods of evaluation were established, every 45 days. Stem length (Lt) and basal stem diameter (Db) were evaluated. Absolute (RGA) and relative (RGR) growth rates were also obtained. Additionally, simple regression tests were made, and a regression was calculated associating RGA from Lt against some climatic variables. Growth evaluation of the plants lasted 205 days.Key results: Germination was obtained in 100%, the process initiated at 12 days. At 205 days, plants reached an average (±1 SD) Lt and Db of 36.5 cm (±5.27) and 8.2 mm (±0.55), respectively. The three evaluation periods showed significant statistical differences. According to regression models, C. elastica grows 0.188 cm day-1 for each millimeter of increase in Db. Conclusions: The use of recently harvested seeds guarantees 100% germination. Different stages of development of the seedling depending on the time (205 days) were obtained. The RGR decreased after the first evaluation, being attributable to the solar radiation. This work demonstrated the feasibility of producing C. elastica plants, reaching the minimal required quality standards in terms of its average Lt and DbAntecedentes y Objetivos: Castilla elastica es una especie nativa de Mesoamérica asociada a diferentes culturas prehispánicas que utilizaban su látex para fines ceremoniales. Es un árbol emblemático, útil en sistemas agroforestales. Este trabajo tuvo por objetivo evaluar la germinación, crecimiento inicial y morfología de C. elastica. Métodos: Se colectaron semillas de 30 árboles y se sembraron en bandejas de polietileno. El inicio de la germinación se determinó por la emergencia de los epicótilos. Se cuantificó el porcentaje de germinación y se establecieron tres periodos de evaluación del crecimiento cada 45 días. Se evaluaron la longitud de tallo (Lt) y el diámetro de tallo (Db). Se obtuvo la tasa absoluta de crecimiento (TAC) y la tasa relativa de crecimiento (TRC). Adicionalmente, se realizaron pruebas de regresión simple entre Lt y Db y se calculó una regresión asociando la TAC de la Lt con algunas variables climáticas. La evaluación del crecimiento tuvo una duración de 205 días. Resultados clave: Se obtuvo 100% de germinación, el proceso inició a los 12 días. A los 205 días, las plantas alcanzaron una Lt y un Db promedio (±1 DE) de 36.5 cm (±5.27) y 8.2 mm (±0.55), respectivamente. Los tres períodos de evaluación mostraron diferencias estadísticas significativas. De acuerdo con los modelos de regresión, C. elastica crece 0.188 cm día-1 por cada milímetro de incremento en Db. Conclusiones: La utilización de semillas recién cosechadas asegura 100% de la germinación. Se obtuvieron diferentes etapas de desarrollo de la plántula en función del tiempo (205 días). La TRC disminuyó después de la primera evaluación atribuible a la radiación solar. Este trabajo demostró la factibilidad de producir plantas de C. elastica y contar con el requisito mínimo como planta de calidad en cuanto a la Lt y Db promedio

Germination, initial growth and morphology of Castilla elastica (Moraceae) in Tabasco, Mexico

Antecedentes y Objetivos: Castilla elastica es una especie nativa de Mesoamérica asociada a diferentes culturas prehispánicas que utilizaban su látex para fines ceremoniales. Es un árbol emblemático, útil en sistemas agroforestales. Este trabajo tuvo por objetivo evaluar la germinación, crecimiento inicial y morfología de C. elastica. Métodos: Se colectaron semillas de 30 árboles y se sembraron en bandejas de polietileno. El inicio de la germinación se determinó por la emergencia de los epicótilos. Se cuantificó el porcentaje de germinación y se establecieron tres periodos de evaluación del crecimiento cada 45 días. Se evaluaron la longitud de tallo (Lt) y el diámetro de tallo (Db). Se obtuvo la tasa absoluta de crecimiento (TAC) y la tasa relativa de crecimiento (TRC). Adicionalmente, se realizaron pruebas de regresión simple entre Lt y Db y se calculó una regresión asociando la TAC de la Lt con algunas variables climáticas. La evaluación del crecimiento tuvo una duración de 205 días. Resultados clave: Se obtuvo 100% de germinación, el proceso inició a los 12 días. A los 205 días, las plantas alcanzaron una Lt y un Db promedio (±1 DE) de 36.5 cm (±5.27) y 8.2 mm (±0.55), respectivamente. Los tres períodos de evaluación mostraron diferencias estadísticas significativas. De acuerdo con los modelos de regresión, C. elastica crece 0.188 cm día-1 por cada milímetro de incremento en Db. Conclusiones: La utilización de semillas recién cosechadas asegura 100% de la germinación. Se obtuvieron diferentes etapas de desarrollo de la plántula en función del tiempo (205 días). La TRC disminuyó después de la primera evaluación atribuible a la radiación solar. Este trabajo demostró la factibilidad de producir plantas de C. elastica y contar con el requisito mínimo como planta de calidad en cuanto a la Lt y Db promedio.Background and Aims: Castilla elastica is a Mesoamerican native species associated with different Prehispanic cultures that used their latex for ceremonial purposes. It is considered an emblematic tree, useful in agroforestry systems. This work aimed to evaluate the germination, initial growth and morphology of C. elastica. Methods: Seeds from 30 trees were collected and planted in polyethylene trays. The start of the germination was determined by the sprouting of the epicotyls. The percentage of germination was quantified, and three periods of evaluation were established, every 45 days. Stem length (Lt) and basal stem diameter (Db) were evaluated. Absolute (RGA) and relative (RGR) growth rates were also obtained. Additionally, simple regression tests were made, and a regression was calculated associating RGA from Lt against some climatic variables. Growth evaluation of the plants lasted 205 days. Key results: Germination was obtained in 100%, the process initiated at 12 days. At 205 days, plants reached an average (±1 SD) Lt and Db of 36.5 cm (±5.27) and 8.2 mm (±0.55), respectively. The three evaluation periods showed significant statistical differences. According to regression models, C. elastica grows 0.188 cm day-1 for each millimeter of increase in Db. Conclusions: The use of recently harvested seeds guarantees 100% germination. Different stages of development of the seedling depending on the time (205 days) were obtained. The RGR decreased after the first evaluation, being attributable to the solar radiation. This work demonstrated the feasibility of producing C. elastica plants, reaching the minimal required quality standards in terms of its average Lt and Db

Tree species with potential for reforestation in coastal zones of the humid tropics

9 Pág.Aim of study: The native species of warm humid climates Ceiba pentandra, Tabebuia rosea, Gliricidia sepium, Enterolobium cyclocar-pum and Brosimum alicastrum are often included in Mexican reforestation programs. We evaluated the growth response in sandy soils of these species that could serve as pioneers in the restoration of coastal areas.Area of study: Alluvial plain in Frontera, Tabasco, Mexico.Material and methods: A total of 1080 plants were planted in 2014 and evaluated for 23 months in 30 plots under a randomized block design with six replications. The sample plots each occupied 36 m2 (each with 16 plants). Survival percentage, stem height (SH), basal diameter (BD) and basal area (BA) were quantified. Survival and growth variables were analyzed using logistic regression and ANOVA for repeated measures, respectively.Main results: At the end of the experiment (2016), high survival was demonstrated in G. sepium (88 %) and in C. pentandra (86 %), while B. alicastrum presented total mortality at six months. The highest values of SH and BD were presented in C. pentandra (2.9 m and 7.8 cm, respectively) and in G. sepium (2.6 m and 4.2 cm, respectively). Gliricidia sepium differed significantly from C. pentandra in terms of BA (5.9 vs. 23 m2 ha-1, respectively).Research highlights: The native species C. pentandra and G. sepium presented high survival and growth in the sandy soils; G. sepiumshowed strong adaptation to the environment and C. pentandra offered suitable coverage, characteristics that are necessary for the success of reforestation and restoration programs.The authors received no specific funding for this work.Peer reviewe

Tree species with potential for reforestation in coastal zones of the humid tropics

Aim of study: The native species of warm humid climates Ceiba pentandra, Tabebuia rosea, Gliricidia sepium, Enterolobium cyclocarpum and Brosimum alicastrum are often included in Mexican reforestation programs. We evaluated the growth response in sandy soils of these species that could serve as pioneers in the restoration of coastal areas. Area of study: Alluvial plain in Frontera, Tabasco, Mexico. Material and methods: A total of 1080 plants were planted in 2014 and evaluated for 23 months in 30 plots under a randomized block design with six replications. The sample plots each occupied 36 m2 (each with 16 plants). Survival percentage, stem height (SH), basal diameter (BD) and basal area (BA) were quantified. Survival and growth variables were analyzed using logistic regression and ANOVA for repeated measures, respectively. Main results: At the end of the experiment (2016), high survival was demonstrated in G. sepium (88 %) and in C. pentandra (86 %), while B. alicastrum presented total mortality at six months. The highest values of SH and BD were presented in C. pentandra (2.9 m and 7.8 cm, respectively) and in G. sepium (2.6 m and 4.2 cm, respectively). Gliricidia sepium differed significantly from C. pentandra in terms of BA (5.9 vs. 23 m2 ha-1, respectively). Research highlights: The native species C. pentandra and G. sepium presented high survival and growth in the sandy soils; G. sepium showed strong adaptation to the environment and C. pentandra offered suitable coverage, characteristics that are necessary for the success of reforestation and restoration programs