Introduction
Eucalyptus bosistoana F. Muell. is a eucalypt species native to
the Australian east coast and eastern high country. As old-growth timber
it has been used in general construction, heavy engineering structures,
sleepers, bridges, wharves, flooring, decking, cladding, cross-arms,
posts, poles and piles \cite{Bootle2005,Poynton1979}
it a good candidate for high value timber products in New Zealand as it
shows high stiffness, class 1 durability
\cite{Australia2005}, exhibits
good growth rates, along with reasonable drought and frost resistance \cite{Poynton1979,Altaner}
used for short rotation timber crops often exhibit excessive
growth-strain production causing problems in the production of saw logs
\cite{Blackburn2014,Valencia2010,Yang2002}
Recently E. bosistoana has been investigated for its potential as
a high value commercial timber species within the dry-land areas of New
Zealand \cite{Altaner,Apiolaza2011,Davies2017} establish an effective initial breeding population, a 4032 tree breeding
trial was established to conduct very early screening (at age 21 months)
of growth and wood properties; growth-strain, under-bark stem diameter,
wood basic density, volumetric shrinkage, tree height and acoustic
velocity. Growth-strain is rarely (if ever) incorporated in breeding
trials as, until recently, with the development of a fast and cheap
method \cite{Chauhan2010,Davies2017}
it has been too expensive and time consuming to assess. For background
information and a review of growth-strain see \citet{Alméras2016}. During the
period between 2009 and 2012, seeds were collected from all known
natural populations. ‘Plus’ trees for growth, form and health were
selected within these populations. As a result, the genetic material
contained in the trial represents all known populations of the species.
Starting from a wild population is not a common occurrence within modern
tree breeding, and presents a unique challenge; how can the genetic
variation be quickly and efficiently distilled down to only the trees
which are likely to be useful in a full-length breeding cycle? Using
early selection methods provides fast and effective ways to screen out
individuals which will prove detrimental to the breeding program,
without the expenditure of growing all individuals to a mature state. As
a consequence, less gain is expected; however, the time and money
invested in the trial is substantially lower. Very early section methods
have been studied and used in breeding trials previously
\cite{Apiolaza2011,Apiolaza2013,Aggarwal2013}.