Berry Crops - Horticulture: Plants for People and Places - page 311

Table 9.2 Species, type and origin of blueberries. (Sources: Ballington 1990 ; Hancock et al. 2008 ;
Lyrene 1998 ; Eck and Childers 1966 ; Eck 1988 ; Rowland et al. 2011 )
Species Type Origin in North America

V. darrowi Lowbush South East USA

V. myrtilloides Lowbush North East USA and Canada

V. tenellum Lowbush South East USA

V. angustifolium Lowbush North East USA and Canada

V. myrsinites Lowbush South East USA

V. corymbosum Highbush North East and Central USA

V. ashei (syn. V. virgatum) Rabbiteye South East USA

The most common commercially-used species are in bold

Since then a series of successful varieties have been released, many of them
with a complex genetic composition as the products of interspecific hybridizations
within the genus (Hancock 2006 ; Brevis et al. 2008 ). This has given rise to the
current wide pedigrees which offer many breeding opportunities to enhance charac-
ters of interest through the use of judicial parents in crossing (yield, small and dry
scar, fruit size, flavor, color, plant habit, and nutritional factors and functionality).
In the mid 1990's, Germany, Australia and New Zealand all started breeding
programs based on open-pollinated seeds from the United States. Today, there are
geographically even more widely dispersed improvement programs, some of which
are based in private companies in Spain, Australia, USA and Chile (Hancock et al.
2008 ) (Fig. 9.8 ).
Because many of the new production areas around the world are distant from
their target consumer markets, postharvest life and fruit condition following long
journeys has become an almost universal focus for highbush blueberry breeding.
Southern highbush breeders have focused on early ripening with better vigour,
yields, disease tolerance/resistance, late bloom (where late frosts are a problem)
and better sensorial characteristics. Northern highbush breeders have focused more
on lateness and extended harvest dates, while also concentrating on flavour (mainly
in very late varieties), disease and pest tolerance/resistance and the ability to be
hand- or machine harvested (Hancock et al. 2008 ).
Much of the breeding to date has been by traditional crossing and selection.
However, there is continuing work on molecular markers and gene mapping, in
order to increase the efficiency of exploitation of genetic resources as well as im-
proving selection methods (Rowland and Levi 1994 ; Rowland et al. 2003 ; Rowland
and Hammerschlag 2005 ; Rowland et al. 2012 ; McCallum et al. 2012 ; Novy et al.
1994 ).

Commercial Production

Blueberries are deciduous shrubs that, depending on species and cultivar, range in
height from 2 to 4 m (Camp 1945 ). They have a fine, fibrous root system (without
root hairs) (Eck and Childers 1966 ; Eck 1988 ) that is concentrated (almost 80 %)