الفهرس 
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Abstract
The aim of this investigation was to study experi-
++ +++
tbe relative proportions of Fe and Fe in
5- ~CONCLUSION
mently
plant and their relation to some natural chelating iron
compounds, sucb as amino acids, in plant supplied with
different rates of iron. Moreover, tbe uptake of some
nutrient ele.ents, namely N, P, K, Ca, Mg, Fe, Zn,
MD, and Cu were determined to learn more about tbe bebaviour
of iron in plant.
To satisfy tbese objectives, two greenhous experiments,
namely sand culture and calcareous soil pots eXperiments
were carried out. Spinacb plant was used as indicator
plant.
)0, 50 and 100 ppm Fe were applied as ferrec-~DTA form.
Six rates of iron, namely control, 5, 15,
~be following results and conclusions were recorded’
1. Total iron uptake increased witb the increasing of Fe-
ED!A application up to tbe bigbest rate used (100 ppm
Fe). Similar trends were also obtained for ferrouS
content in plant. In the mean time, Fe+++ content was
significantlY increased only up to 15 ppm Fe application.
But at bigher rates, 15, )0. 50, and 100 pp.
Fe, there were no significant differences noticed.
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reflected on iro.
4. Although nitrogen and phosphorus concentrations in
spinach plant were significantly increased with each
increment of iron application up to 50 ppm. yet iron
addition at low rates. up to 15 ppm Fe, enchanced nitrogen
concentration in plant but higher levels did not
affect these elements materially over that resulted
from the 15 ppm Fe.
5. The P/F.++ ratio tended to decrease significantly by
increasing the rate of iron application. but there was
insignificant differences between P/Fe+++ ratio at all
rates of iron application. Such trend means that this
ratio tended to remain constant regardless of the rate
at iron application and that any increase of ferric
iron is intimately correlated with an increase ot phosphorus
concentration and vice-versa. ~uch data suggest
that the capacity of the plant to absorb and hold iroB
in a soluble and mobile form becomes less as the phosphorus
concentration in the plant rises.
6. Iron additions partiCUlarly at low rates enhanced the
potassium uptake. but differences tended to diminished
as the rate of iron application was increased.
7. No clear trend was noticed in the uptake of calcium
and asgnesium under these conditions of experiments.
8. Concerning manganese. zinc and copper. iron application
up to 5 ppm Fe increased the manganese and zinc
concentration in plant. however. byond this rate,
both elements were significantly decreased. Copper
significantly decreased with increasing the rate of
iron application.
9. In sand culture experiment. F’e-~DTA applications affected
the concentration of individual free amino acids
differently. Compared to the control. iron application
decreased the concentration of free alanine, leucine.
isoleucine. serine. and phenylalanine. However no clear
trends was noticed with respect to glycine. valine, proline.
arginine and histidine. On the other hand. there
was an obvious accumulation of free aspartic, glutamic,
threonine and cysteine amino acids with iron application.
The .ost important free amino acids chelated with
ferrous iron were as followl
Cysteine> histidine> aspartic acid~serine>glutamic
acid.
10. In calcareous soil experiment, there were decreasing
in phenylanine, leucine, valine, arginine, alanine,
and proline than the control, whereas, no clear trends
were noticed in tqe concentration of free serine, histidine,
glycine, and threonine. On the other hand,
there was a tendency for accumulation of free cysteine,
aspartic acid, and glutamic with increasing the rate of
iron application.
The most dominant and important free amino acids
chelated with Fe++ were as followl
cy.hiD> histidine> aspartic acid”/ serine» glutamic acid
10. Results indicated that the amount of Fe++ chelated with
amino acids are Tery small if compared with the concentration
or the content of Fe++ in plant. Under physiological
pH, it may be concluded that although the free
r
amino acids can bind or chelate with fe~ous iron, yet
the free amino acids are not the dominant compound chelated
with iron in cell or through iron translocation,
consequently ferrous and ferric iron, or the active
fora. of iron, aust be bound or chelated with others
organic co.pounds, .ost probably organic acids and phytoferritin
which seem to play an important role in
proteoting the active iron from precipitation or changing
te inactive form.