Breeding of advanced generation of Eucalyptus macarthurii-growth parameters and development of a near infrared (NIR) calibration model to predict whole tree pulp yield using non destructive cores.
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2008
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Abstract
Eucalyptus macarthurii is one of the cold tolerant eucalypt species grown in South Africa
for pulp and paper. However, little research has been done on this species’ growth
performance. A study was therefore initiated to: i) analyse growth characteristics of
Eucalyptus macarthurii at two sites and to calculate genetic parameters (genetic and
phenotypic correlations, heritabilities and genetic gains), ii) develop a non-destructive
near infrared calibration model to predict whole tree pulp yield of Eucalyptus macarthurii,
and iii) screen a second generation Eucalyptus macarthurii breeding population, using
the developed near infrared calibration model on core samples, to predict screened pulp
yield and to rank and identify families with superior pulping properties.
Eucalyptus macarthurii population growth data (diameter under bark, diameter
over bark, bark thickness, bark stripping, height, basic wood density and stem form)
were measured at Pinewoods and Vlakkloof sites and their respective genetic
parameters calculated. Genotype by environment interaction was found in this
population, indicating that different populations should perhaps be developed
independently of each other for the two sites. Genetic and phenotypic correlations
between diameter over bark and diameter under bark were, 0.96 and 0.98 for
Pinewoods and 0.98 and 0.99 for Vlakkloof, respectively. These correlations indicated
that selection of diameter over bark would lead to a positive indirect selection for
diameter under bark. The heritability estimates also ranged from 0.03 to 0.23 at both
sites, which indicated a reasonable response to selection. The predicted gains for all
traits found at Pinewoods were higher than those at Vlakkloof for progeny trials E76/P1,
except height for progeny trial E76/P2, which was 2.09m at Pinewoods site and 3.52m at
Vlakkloof site which showed that, selection for taller trees will be more effective at
Vlakkloof site.
A preliminary study was undertaken from eleven second generation trees (2007
tree collection) to investigate if the radial strip core taken at breast height predicts the
whole tree wood properties. Correlations found between laboratory Kraft pulping of
whole tree wood discs and whole tree NIR spectra with that of the radial strip core NIR
spectra were 0.9472 and 0.9506, respectively. These results confirmed that NIR spectra
of the radial strip core at breast height predict the whole tree wood properties. A non-destructive near infrared calibration model using wood samples was
obtained from Eucalyptus macarthurii felled trees. The wood samples were chipped into
wood chips, pulped using Kraft pulping (reference method) and a sub-sample of wood
chips of the same trees were ground into sawdust samples and analysed through near
infrared spectroscopy for screened pulp yield. The screened pulp yield values obtained
from both processes had a narrow screened pulp yield range of 40 to 48%. The
Eucalyptus macarthurii screened pulp yield values obtained from both processes, as well
as from values obtained from other eucalypt species, were subjected to Vision®
Software for calibration and validation of the near infrared calibration model.
The results indicated a strong calibration correlation coefficient of 94%, between Kraft
pulping and near infrared spectroscopy with a validation coefficient of 89%. The strong
correlation and validation coefficient indicated that a reliable non-destructive near infrared
model to predict screened pulp yield was successfully developed. The successful
development of the valid calibration model required a wider range of other eucalypts
species, which improved the development of the model.
The developed calibration model was applied to the second generation breeding
population planted in KwaZulu-Natal and Mpumalanga provinces, using wood core
samples obtained from standing trees for the prediction of screened pulp yield. The
highest screened pulp yield achieved was 48%, which compared well to that found for
Kraft pulping, which confirmed the success of the development of the calibration model.
There was a wide scope of growth variation found amongst traits, which will be
useful in selecting superior trees for the next generation. The development of the nondestructive
near infrared calibration model was a success due to the strong correlation
coefficients found between the screened pulp yields obtained from Kraft pulping and
near infrared spectroscopy processes, which was achieved by the inclusion of other
eucalypt species in the dataset.
The calibration model can be used to select the top performing individual and
family trees for the next generation based on screened pulp yield. Tree improvement
trials can now be conserved for further breeding, without felling the trees for
determination of pulping properties.
Description
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.
Keywords
Eucalyptus--Breeding--South Africa, Eucalyptus--Genetics., Wood-pulp--South Africa., Eucalyptus--Yields--Mathematical models., Near infrared spectroscopy--South Africa., Theses--Genetics.