Michael Stine

WITHIN TREE VARIATION OF LIGNIN, EXTRACTIVES, AND MICROFIBRIL ANGLE COUPLED WITH THE THEORETICAL AND NEAR INFRARED MODELING OF MICROFIBRIL ANGLE

A theoretical model was built predicting the relationship between microfibril angle and lignin content at the Angstrom (A) level. Both theoretical and statistical examination of experimental data supports a square root transformation of lignin to predict microfibril angle. The experimental material used came from 10 longleaf pine (Pinus palustris) trees. Klason lignin (n=70), microfibril angle (n=70), and extractives (n=100) were measured and reported at different ring numbers and heights. All three traits were strongly influenced by ring age from pith while microfibril angle and extractives exhibited more of a height effect than lignin. As such, the multivariate response of the three traits were different in the axial direction than the radial direction supporting that care needs to be taken when defining juvenile wood within the tree. The root mean square error of calibration (RMSEC) for microfibril angle of the theoretical model (RMSEC = 9.8) was almost as low as the least squares regression model (RMSEC = 9.35). Microfibril angle calibrations were also built from NIR absorbance and showed a strong likeness to theoretical and experimental models (RMSEC = 9.0). As a result, theoretical and experimental work provided evidence that lignin content played a significant role in how NIR absorbance relates to microfibril angle. Additionally, the large variation in extractives content coupled with sampling procedure proved important when developing NIR based calibration equations for lignin and microfibril angle.

Genetic improvement of fiber length and coarseness based on paper product performance and material variability - a review

Improvement of specific gravity through tree breeding was an early choice made in the mid 20th century due to its ease of measurement and impact on pulp yield and lumber strength and stiffness. This was often the first, and in many cases, the only wood quality trait selected for. However, from a product standpoint, increased specific gravity has shown to lower many paper strength and stiffness properties and has been assumed to be directly attributable to increased fiber coarseness. As a result, it is currently not clear which fiber trait would best benefit a tree improvement program for paper products. This review found coarseness to be perhaps more important to paper strength and stiffness whereas tracheid length showed better promise from a breeding point of view due to its independence from specific gravity. However, both traits possessed strong heritability and influence on product performance and thus both would be beneficial to breed for depending on organizational goals and end product mix. The objective of this paper is to review and prioritize coarseness and tracheid length from both an end use and raw material perspective. To aid in prioritization, the variation, correlation, and heritability of both traits were reviewed along with significant genetic and phenotypic correlations. Variation trends within and between families as well as within a tree were reviewed.

Tracheid length prediction in Pinus palustris by means of near infrared spectroscopy: the influence of age

The prediction of tracheid length using near infrared (NIR) wavelengths can provide either useful or misleading calibrations depending on the context. This can happen since tracheid length is not directly related to the absorbance at any wavelength but is instead the result of a secondary correlation with some unknown chemical constituent. In this work, the effect of tree age and height on NIR predictability was investigated since tracheid length and chemistry may vary as a function of location within the tree. It was found that tracheid length predictability did not change with height but decreased with age. As a result, predicting tracheid length regardless of age was good (R2 = 0.72) while predictability holding age and height constant was mostly low to moderate with the exception of rings 1 and 4 which was quite strong.ZusammenfassungDas Abschätzen der Tracheidenlänge mittels NIR-Spektroskopie kann je nach Sachlage zu brauchbaren oder auch irreführenden Kalibrierungen führen. Das kommt daher, dass die Tracheidenlänge nicht unmittelbar mit der Extinktion bei irgendeiner Wellenlänge in Beziehung steht, sondern über eine indirekte Korrelation mit unbekannten Inhaltsstoffen. In dieser Arbeit wird der Einfluss des Baumalters und der Höhe auf die Verlässlichkeit der NIR-Messung untersucht, da sowohl die Tracheidenlänge als auch die chemischen Bestandteile je nach Position im Baum varieren können. Es zeigte sich, dass die Vorhersagbarkeit der Tracheidenlänge sich nicht mit der Baumhöhe ändert, jedoch mit dem Alter abnimmt. Insgesamt war die Vorhersagbarkeit der Tracheidenlänge unabhängig vom Alter recht gut (R2=0,72); bei konstantem Baumalter und -höhe war sie jedoch mäßig bis niedrig außer für die Jahrringe 1 und 4, wo die Korrelation sehr streng war.