Agriculture Reference
In-Depth Information
Fig. 10.2 Dilution curve for a generic essential nutrient as defined by six n
c
values determined for
six plant developmental stages
concentration of the nutrient, without adopting the traditional chemical analyses, is
the most difficult challenge to overcome.
Since nitrogen is the nutritional element that most often affects crop production
and the current world use of N fertilisers is approximately 90 million metric tons
(with an estimated cost of about $50 billion), it is reasonable that several research
efforts have been focused on the fine tuning of non-invasive methods for the
determination of N levels in shoots throughout the entire growth cycle of crops as
a guide to N-FBMPs (for an exhaustive review see Samborski et al.
2009
). Assum-
ing nitrogen as an example, in the next paragraph we briefly summarize the
advances on the non-destructive approaches developed or under investigation for
monitoring the nutritional status of a crop.
Non-destructive Monitoring of Crop Nutritional Status: The
Example of Nitrogen
Nitrogen availability affects chlorophyll content in leaves (Schlemmer et al.
2005
)
and as a consequence the level of this pigment is considered a good indicator of the
nitrogen nutritional status of a crop (Samborski et al.
2009
and references therein).
Instruments analysing the spectral properties of leaf tissue to estimate their chlo-
rophyll content (optical chlorophyll meters) have been developed to evaluate the
need for agricultural N applications. Due to the pigment
s light absorption proper-
ties (in the visible wavelength range), the higher the chlorophyll content, the higher
the reflectance of the leaf (in the 525-680 nm range) and consequently, the higher
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