Agriculture Reference
In-Depth Information
because there is a linear relationship between the SPAD value and nitrogen content
of crop. The trace elements can be determined by atomic absorption (AA) spectrom-
etry. AA spectroscopy uses the absorption of light to measure the concentration of
gas-phase atoms. Because samples are usually liquids or solids, the analyte atoms or
ions must be vaporized in a flame or graphite furnace. The atoms absorb ultraviolet
or visible light and make transitions to higher electronic energy levels. The analyte
concentration is determined from the amount of absorption. Applying the Beer-
Lambert law directly in AA spectroscopy is difficult because of variations in the
atomization efficiency from the sample matrix, and nonuniformity of concentration
and path length of analyte atoms (in graphite furnace AA). Concentration measure-
ments are usually determined from a working curve after calibrating the instrument
with standards of known concentration. AA spectrometers may be used to analyze
the concentration of more than 70 different elements in a given sample solution,
making them a very valuable instrument in any laboratory procedure that requires
reliable measurements and reproducibility.
The physiological information is mainly about the determination of protein, amino
acids, enzyme, antioxidant index, the respiration, the photosynthesis, and so on.
Respiration and photosynthesis influence the photosynthetic rate, transpiration rate,
stomatal conductance, leaf temperature, photosynthetically active radiation, air tem-
perature, air humidity, etc. All the above-mentioned information is significant for the
healthy growth, crop quality, and quantity of crops. The detection of physiological
information is more complicated than nutritional information. The protein content can
be determined by the Kjeldahl method and the Dumas combustion method. The amino
acids can be determined by high-performance liquid chromatography and automatic
amino acid analyzer with sample pretreatment. Automated amino acid analyzer by the
NIN hydrin method of post-column derivatization, high sensitivity, and high revoluta is
achieved for all amino acids. The Automatic Amino Acid Analyser is used for deter-
mination of amino acids in protein and peptide hydrolysates, for the determination of
free amino acids in physiological liquids, and extracts as well. Respiration and photo-
synthesis can be measured by respiration and the photosynthesis system. The CIRAS-2
Portable Photosynthesis System is suitable for the measurement of leaf gas exchange.
When it is fitted with the integral Chlorophyll Fluorescence Module, developed in coop-
eration with Hansatech Instruments, the system is capable of performing simultaneous,
automated measurements of both leaf gas exchange and chlorophyll fluorescence. After
application of certain accessories, the system can be used for measurement of leaf gas
exchange, soil CO
2
flux, canopy assimilation, and chlorophyll fluorescence. There are
several sensors for the temperature and humidity measurement.
Ecological information includes vegetation index of crop, shape information of
crop growing, color information, geometric information, and three-dimensional
structure information. Detection for ecological information is mostly done in the
laboratory using remote sensing technology, machine vision technology, image
scanning technology, laser scanning technology, structured light scanning technol-
ogy, and so on. The instruments for the vegetation index are satellites, unmanned
vehicles, and canopy scanning instruments. The shapes of crops are normally deter-
mined using traditional instruments such as rulers, protractors, and imaging pro-
cessing. The 3-D structure can be obtained by using handheld laser scanner Fast SCAN
