Agriculture Reference
In-Depth Information
et al.
2012
). If this is the case traits, which never occur together in nature may still
be combined in one crop.
Finding plant traits, which improve Yp and NUE is a major aim of modern
breeding programs. The genetic variability of crops, as well as of the model plant
Arabidopsis thaliana
, may serve as sources of diversity and promising traits may
then be incorporated into transgenic crop plants. Additionally future techniques
might enable the transfer of physiological traits such as C
4
metabolism (Leegood
2002
) or N fixation (Charpentier and Oldroyd
2010
; Beatty and Good
2011
)
between distantly related species. In this way, ecological but non-physical trade-
offs could theoretically be overcome faster, and crop plants could be complemented
with physiological properties that they would never gain through breeding. The
diversity present in nature is potentially a rich source of traits that could improve
the NUE of crops. There may be plant species that evolved mechanisms to use
nutrients much more efficiently than crops but which science has yet to exploit. In
particular species from nutrient-poor habitats are very promising candidates. Thus
transgenics could be a useful tool to engineer crops whilst ecophysiology delivers
the ideas of how these modifications will look.
Conclusions
Plant NUE is as complex and multi-dimensional as the plant itself. Conse-
quently the greatest challenge, but also the greatest opportunity for modern
plant nutrition research, is the integration of various disciplines and
approaches. Use of state-of-the-art methods in transcriptomics,
metabolomics, and proteomics give researchers unprecedented opportunities
to obtain huge amounts of information with high resolution (see the other
chapters of this topic), not least enabled by the exponential increase of
computing performance since its emergence (Moore
1975
; Kurzweil
2001
).
The growing understanding of complex molecular networks and their holistic
responses to alterations in nutrient availability contributes to uncovering the
genetic basis of NUE and shows how complex metabolic pathways are
interacting on a molecular level. However, the real power of molecular
techniques for future crop breeding can only unfold if the complexity of the
underlying physiological processes and their contribution to NUE is to be
further understood.
Additionally there are physiological trade-offs that challenge the improve-
ment of NUE. It might be possible to overcome some of them by modern
molecular breeding techniques; others might be physically determined and
display a real limit for the improvement of NUE. Further investigation is
necessary to determine the physiological basis of these trade-offs before tools
such as genetic manipulation may be used to overcome them. As studies on
NUE usually focus on only one nutrient (and usually only N or P), there is
little data available on possible trade-offs between the NUE of different
(continued)
