GROWING WHEAT FOR HIGH ALCOHOL YIELD –HOMOGENEOUS AND HETEROGENEOUS APPROACHES - Soybean and Wheat Crops: Growth, Fertilization, and Yield - page 177

would be mirrored by gains in biomass yield. Sarandon and Sarandon [51], however, noted an
increase in biomass, within a mixture, even in the absence of an increase in grain yield. A
considerable amount of further research in this area will, therefore, be required, particularly as
there does not appear to have been any studies on the effect that increasing component
number would have on biomass content.
C ONCLUSION
The cultivation of wheat, for potable alcohol production, will continue to be important in
Scotland although, at the present time, the extent to which wheat will be used for fuel alcohol,
within the UK, is unclear. Development of biofuel production, especially from biomass,
would have implications for the plant breeding industry, since, at present, there is no selection
of biomass, either for its content or its suitability for processing, within UK cereal breeding.
The use of fuel alcohol derived from grain remains controversial [71], but utilising wheat for
this purpose could require 3m tonnes per annum within the UK, initially [58]. Without this
market, it is difficult to see distilling quality being a major target for wheat breeders.
As wheat, however, remains the major human food crop, on a global scale, there will be a
continuing requirement to enhance its productivity, to meet demands from a population
predicted to reach 10 billion during the 21 st century. The possibility of exploiting
biotechnology to increase yield [60] is likely to be explored, and the potential to enhance
nitrogen uptake under low N conditions [21], [71] has been briefly considered earlier in this
chapter. A more far-reaching application of genetic modification would be to develop wheat
varieties capable of association with nitrogen-fixing bacteria, thus greatly reducing the need
for inorganic fertilsers. Recent work has enhanced the understanding of root nodule formation
in legumes, permitting genetically modified plants to form nodules in the absence of Rhizobia
[20]. This raises the possibility [25] of transferring the capacity for nodule formation, an
essential aspect of the symbiotic relationship with nitrogen-fixing bacteria, to non-leguminous
plants, but such developments are unlikely in the immediate future.
However, there will be both economic and environmental pressures to grow crops with
reduced inputs, particularly of N fertilisers, due to their contribution to energy use [48], [65]
and greenhouse gas emissions [71]. This is likely to encourage more effective targeting of
fertiliser application and the cultivation of crops that can maximise exploitation of above- and
below-ground resources. Additionally, if fertiliser prices continue to increase, maximising
yield, irrespective of input costs, will become an unattractive option, as growers seek an
economic optimum for inputs [61]. It is also widely predicted that current changes in climate
may give rise to greater fluctuation in weather and increased likelihood of more extreme
conditions. Under these circumstances, stability in performance may become as important, if
not more so, than yield potential.
Future plant breeding targets will require to address such issues and this will have
implications for national testing systems under which recommendation are often based,
currently, on yield obtained under comprehensive fertiliser and pesticide regimes. It may also
be appropriate to re-consider the way that varieties are deployed in agriculture. As
homogeneity appears to be much less of an issue for wheat quality markets than it is for
malting barley, varietal mixtures may be grown more widely than at present. Mixtures have