Article

Efecto de la procedencia geográfica y de la fertilización en la fenología del brote terminal en plántulas de "Pseudotsuga sp"

Agrociencia (Impact Factor: 0.26). 01/2006; 40(1).
Source: OAI

ABSTRACT

Con el propósito de evaluar las implicaciones del uso de germoplasma fuera de su hábitat natural y en la producción de plantas en vivero, se evaluó la influencia de la procedencia geográfica, así como el efecto de la fertilización, sobre las características fenológicas del brote terminal en plántulas de Pseudotsuga sp. obtenidas de semillas procedentes de siete poblaciones de diferentes regiones del país. Los resultados mostraron una variación significativa (p¡Ü¡Ü¡Ü¡Ü¡Ü0.01) entre poblaciones en las fechas de inicio y terminación y en la duración del período de crecimiento del brote terminal, con diferencias de siete semanas entre las poblaciones extremas. El rompimiento de la yema terminal se correlacionó negativamente con la altitud del sitio de origen (r=-----0.78), sugiriendo una relación adaptativa con la temperatura umbral requerida para iniciar el crecimiento del brote. Aunque no se encontró un patrón geográfico bien definido, las poblaciones del norte de México tienen una estacionalidad de crecimiento del brote diferente a las del centro de México. Además, las poblaciones del centro de México presentaron menor heterogeneidad individual en los eventos fenológicos asociados al crecimiento del brote. Al utilizar una dosis elevada de fertilización se adelantó la fecha de inicio del crecimiento en 10 d y se retrasó la formación de la yema terminal en 9 d, aumentando el período de crecimiento del brote en casi tres semanas y reduciendo la heterogeneidad de los eventos fenológicos.

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Available from: Jesús Vargas-Hernández
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    • "In Mexican populations of P. menziesii (Mirb.) Franco, studies based on morphological (Reyes et al., 2006) and phenological characteristics (Acevedo et al., 2006), indicate an outstanding differentiation between the populations of the northern region and those of the south-central region of the country, which represent the southern limit of the natural distribution of the genus Pseudotsuga in the world. The high degree of population differentiation (F st =0.298) has been confirmed based on isoenzymatic markers in a group of Mexican populations of this species, as well as the reduced level of genetic flow between them (Cruz, personal communication 1 ). "
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    ABSTRACT: The Mexican populations of Pseudostuga menziesii (Mirb.) Franco have a restricted and fragmented natural distribution, especially in the central region, therefore there is a risk that these populations will be lost due to the effects of climatic change. With the purpose of suggesting adequate measures for their conservation, an evaluation was made of the mating pattern and its effect on the inbreeding level in three natural populations of P. menziesii, two of the north and one of the central region of México, based on the percentage of cross pollination. With the information of five polymorphic loci, the allelic frequencies of pollen and ovules were estimated, along with the proportion of mating in each population using multilocus (tm) and single locus (ts) models. No differences were found in the allelic frequencies of pollen and ovules, which indicates that the pollen comes from the same community as the mother trees. The value of t̂m in the two northern populations was close to 90%; in the central population it was 49% as a result of a high percentage of selfing. The similarity of the estimations of the degree of cross breeding (tm and t̂s), indicates that selfing is the principal form of inbreeding in the populations evaluated. Despite the high percentage of cross breeding in the northern populations, the paternity correlation coefficient in them was over 60%, indicating a reduced number of pollinating trees. The implications of these results in the conservation of the populations are discussed, especially in the central region.
    Full-text · Article · Apr 2008 · Agrociencia
  • Source
    • "In Mexican populations of P. menziesii (Mirb.) Franco, studies based on morphological (Reyes et al., 2006) and phenological characteristics (Acevedo et al., 2006), indicate an outstanding differentiation between the populations of the northern region and those of the south-central region of the country, which represent the southern limit of the natural distribution of the genus Pseudotsuga in the world. The high degree of population differentiation (F st =0.298) has been confirmed based on isoenzymatic markers in a group of Mexican populations of this species, as well as the reduced level of genetic flow between them (Cruz, personal communication 1 ). "
    [Show abstract] [Hide abstract]
    ABSTRACT: The Mexican populations of Pseudostuga menziesii (Mirb.) Franco have a restricted and fragmented natural distribution, especially in the central region, therefore there is a risk that these populations will be lost due to the effects of climatic change. With the purpose of suggesting adequate measures for their conservation, an evaluation was made of the mating pattern and its effect on the inbreeding level in three natural populations of P. menziesii, two of the north and one of the central region of México, based on the percentage of cross pollination. With the information of five polymorphic loci, the allelic frequencies of pollen and ovules were estimated, along with the proportion of mating in each population using multilocus and single locus models. No differences were found in the allelic frequencies of pollen and ovules, which indicates that the pollen comes from the same community as the mother trees. The value of in the two northern populations was close to 90%; in the central population it was 49% as a result of a high percentage of selfing. The similarity of the estimations of the degree of cross breeding indicates that selfing is the principal form of inbreeding in the populations evaluated. Despite the high percentage of cross breeding in the northern populations, the paternity correlation coefficient in them was over 60%, indicating a reduced number of pollinating trees. The implications of these results in the conservation of the populations are discussed, especially in the central region.
    Full-text · Article · Jan 2008 · Agrociencia
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    • "Wide-ranging differences among Mexican Pseudotsuga populations have been found in morphological and anatomical characteristics of cones and leaves (Reyes et al., 2005) and in vegetative plant phenology (Acevedo et al., 2005). Despite the studies of Acevedo et al. (2005) and Mápula et al. (1996; 2006) geographic variation in germination and seedling vigor characteristics of Pseudotsuga is not known. Based on the aforesaid, this study was carried out in order to determine the variation in germinative capacity and energy, number of cotyledonary leaves, hypocotyl height, height at nine months of age, and seedling survival of eleven Mexican Pseudotsuga menziesii populations. "
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    ABSTRACT: Pseudotsuga menziesii (Douglas-fir) is one of the most valuable conifers in world wood production, whose geographic variation in México for characteristics of germination and seedling vigor is not known. The geographic variation pattern in germination characteristics and initial progeny growth of 11 natural Pseudotsuga menziesii populations in México was evaluated. Seed from 114 trees covering most of the natural distribution of the genus (25 to 17° N) was stratified by seven weeks and sown. Significant variation (p≤0.01) was found among populations and among the trees within them in all the characteristics evaluated. The differences among sites were notable in germination percentage and rate and seedling hypocotyl height, with lesser differences in cotyledon number, total height at nine months and their survival. Among populations, germination varied from 7.7 to 84.0%, germination energy (days to reach 50% of germination) from 5.4 to 12.8 d, hypocotyl height from 20.6 to 24.8 mm. At nine months, plant height was 97 to 104 mm, nine sites reached survival higher than 94%, but Ixtepeji, Oaxaca, and Presa Jaramillo, Hidalgo, had 50% survival. P. menziesii seed of localities from central México has less vigor and germination capacity than that of the north.
    Full-text · Article · Nov 2006 · Agrociencia
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