Breeding Willow for Short Rotation Coppice Energy Cropping - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 78

SRC willow produces wood chip as a basic fuel. However, many consider it
second rate when compared to wood chip from high forest systems. Clearly the
greater proportion of bark in a multiple, low diameter (120 mm) stem coppice
system increases the inorganic components of detriment to thermochemical con-
version technologies relative to larger diameter tree branches. As the demand for
wood fuel continues to grow, this is placing tremendous pressure on forestry
resources in many areas of the world. Planting new forests has a long lead time,
and planting newly bred SRC willow cultivars (with low inorganic components) on
non-arable land offers great potential to fuel thermochemical energy conversion
facilities. Forest trees have low adaptability; breeding is extremely limited, and the
long lifetime of a plantation leaves them vulnerable to rapid environmental change.
Classical breeding, backed up by modern biotechnology, in willows offers much
greater adaptability.
The multifunctionality of SRC willow plantations are already being utilized and
have the potential to be exploited further. They provide biodiversity benefits, when
compared to conventional arable cropping rotations, and can be used for bioreme-
diation, establishing riparian buffer zones to prevent erosion and agrochemical
runoff and potentially carbon sequestration.
Fermentation of willow (to liquid fuels) is less well developed commercially
than the thermochemical conversion technologies. Initially there is potential to
ferment the available sugars and direct the residue to thermochemical conversion
facilities. Even greater promise is offered by more advanced bio-refining where
energy is only one product from the crop [ 33 ]. Rothamsted Research have begun a
metabolomics profiling program, in part to identify novel and higher value products
from the willow crop but also to support the crop improvement per se.
Conclusion
Willow offers tremendous natural genetic variation identified in the world's germ-
plasm collections and potentially much more to be discovered. The breeding system
is simple and breeding timescales short. Therefore, there is vast potential for
bioenergy today and for rapid progress into the future. Unlike major food crop
species where breeding effort must be concentrated on arable land, the willow
breeding effort may be concentrated upon land types offering fewer options and
greater challenges with, it may be expected, greater gains on such land.
References
1. Argus GW. Infrageneric classification of Salix (Salicaceae) in the New World. Systematic
botany monographs. Ann Arbor: The American Society of Plant Taxonomists 1997; 52(1):121.