No abstract

Despite the extensive distribution and use of Pinus oocarpa in Mexico, knowledge on the range of genetic variation and magnitude of quantitative parameters of the defensive structures of the species is rare. Our study attempts to fill this gap by providing a comprehensive assessment of resin duct traits in mother trees and their offsprings in an open-pollinated trial of P. oocarpa. Resin ducts are fundamental structures of the defense mechanisms of the coniferous trees. They vary depending on the age of the tree, the genotype, the species, and may be influenced by environmental factors. We investigated intraspecific variation among families of the resin duct system in secondary vascular tissues (wood and inner bark) of P. oocarpa trees. Our study attempts to explore the variance and the possible genetic control of these defensive structures. We hypothesized that the resin duct features analyzed would vary with the tree’s genetic make-up. We analyzed samples from two groups of trees. First, from mature mother trees selected as superior in resin yield. Second, from their six-year-old off-springs established in a progeny trial. Axial and radial ducts showed differences in their size and quantity, between wood and bark and between ages. The axial duct density showed differences among families, and the heritability estimates were moderate. In P. oocarpa trees selected as phenotypically superior in resin yield, the size of its constitutive resin ducts is a less variable trait, and the differences in axial duct density can be attributed to genetic factors.

Characterization of Ceiba aesculifolia (CA) fibers by various techniques is herein reported. The seed pods were collected, and the fibers surrounding the seeds were characterized or treated in an oven at 100 °C prior to characterization by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis coupled with a differential scanning calorimeter (TGA-DSC). The SEM micrographs showed that the natural material is comprised of tubes of external diameter of approximately 27 μm and a mean wall thickness of about 0.62 μm. The results also indicated that the tubes begin to decompose at approximately 220 °C.

Mexico ranks 5th in worldwide resin production. Pinus oocarpa is the most widely tapped pine tree in Mexico. Michoacán (central-western Mexico) is the first nationwide state producer of resin. Despite the P. oocarpa relevance, there is no genetic improvement program in the country for resin production. We evaluated the degree of genetic control for growth, anatomical traits, resin yield, and the correlation among them at an early age (five-years-old for growth, six for resin, and anatomical traits) in a P. oocarpa half-sib progeny trial. Families were originated from selected mother trees, based on their resin yield. We found significant genetic variation among families for stem volume (h 2 i = 0.12, h 2 f = 0.35), traumatic ducts (diameter: h 2 i = 0.63, h 2 f = 0.51; area: h 2 f = 0.81), and resin yield (individual and family narrow-sense heritability: h 2 i = 0.20, h 2 f = 0.52), and a positive correlation between diameter and area of traumatic ducts with resin yield (Pearson correlation: r= 0.73, p= 0.04; r= 0.71, p= 0.0497; respectively). Results suggest that the early selection (six-years-old) of superior P. oocarpa families, based on resin yield (estimated by microchipping technique), and/or based on larger diameter and area of traumatic ducts, appears to be a feasible strategy to develop seed orchards able to provide genetically improved seeds for intensive resin tree plantations. That would be an important alternative for a state as Michoacán, Mexico, where natural P. oocarpa stands are being replaced for avocado orchards for exportation.

CienciaUAT RESUMENLa Reserva de la Biosfera Mariposa Monarca (RBMM) presenta un nivel crítico de deforestación que pone en peligro el fenómeno migratorio de la mariposa. Variables biofísicas, como el índice de área foliar (LAI) y la fracción de radiación fotosintéticamente activa absorbida por las plantas (fAPAR), pueden ayudar en el diagnóstico del estado de una masa forestal. Es posible construir mapas de alta resolución de estas variables con imágenes satelitales y datos de campo; también existen series de mapas globales de baja resolución. En el presente trabajo se construyeron mapas de LAI y fAPAR de la RBMM, a partir de una imagen SPOT-4 con resolución espacial de 20 m y datos de campo, y se compararon con los mapas de la serie GEOV1 con resolución espacial de 1 km, de las mismas variables y fecha, con el fin de valorar la posibilidad de utilizarlos conjuntamente. Para construir los mapas de alta resolución, se realizó un muestreo en el verano de 2007, en 62 sitios de bosque en la RBMM. A cada sitio se asociaron los datos radiométricos del pixel correspondiente de una imagen SPOT de agosto de 2007, en la que las zonas con nubes se sustituyeron por los mismos pixeles de imágenes de fechas cercanas. Para cada variable, se ajustaron 45 modelos lineales, entre los que se eligió el de mayor índice de concordancia (0.45). Estas funciones se aplicaron a cada pixel de la imagen SPOT para construir los mapas, que se validaron con datos de campo, presentando errores relativos aceptables (RMSEr, LAI: 20 %; fAPAR: 8 %). La comparación de los mapas con los GEOV1 mostró una correlación significativa (r > 0.5) y un error relativo aceptable (RMSEr, LAI: 19 %; fAPAR: 8 %). Este resultado alienta la utilización conjunta de mapas de alta resolución y series de tiempo.

Most pine species produce high amounts of viable seeds, and this characteristic varies according to number of trees and soil conditions. The assessment of reproductive indicators under such conditions has been documented. However, in species such as Pinus martinezii, whose populations are small, scattered and fragmented, information on such reproductive characteristics is limited. The objective of this work was to evaluate cone size, reproductive indicators and inbreeding index of P. martinezii from sites with different degrees of soil degradation. Thirty cones were collected from eight trees at two sites in the state of Michoacán. The data were analyzed using a two-way ANOVA, whose factors were provenance, family and the interaction between them. In addition, a correlation was made between reproductive parameters and cone size. The values obtained per cone were: 80.6 to 129.6 potential seeds, 15.7 to 79 % developed seeds, 8.6 to 50.6 % full seeds, 39 to 91.1 % vain seeds, 20.9 to 99 % abortive ovules and 0.39 to 0.91 inbreeding index. A significant difference was observed between provenances and families in most of the evaluated variables. Reproductive indicators show a substantial loss of seeds due to abortive ovules and vain seeds, which indicates reproductive problems due to the low number of individuals. This situation is exacerbated by soil degradation.