الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
SUMMARY
In a trial to elucidate some aspects of the iron
chlorosis phenomenon, the effects due to application of
iron, calcium carbonate and phosphate were investigated.
Three separate greenhouse experiments using a sand culture
technique, with sorghum bicolor as an indicator plant,
were conducted. The involved treatments can be listed as
follows:
~xperimen!-!:
Iron applicL~tion as FeS04 or Fe-EDTA was performedat six rates
for each source namely; 0, 5, 10, 20, 40 and 60 ppm Fe.
Experiment II:
Iron and calcium carbonate applications were carried
out at rates of 0, 10 and 20 ppm Fe, as FeS04 and 0. 2, 4
and 8% C aC03 ”
~periment III:
phosphate (KH) application was performed at rates
of 0, 20, 40 and 60 ppm P, while Fe waS applied to all
treatments at one rate (20 ppm Fe) as FeS04”
The determined parameters included the dry matter of
sorghum (roots and shoots) as well as the concentration
and total uptake of Fe, P, Ca, Mg and Mn in both plant
parts.
Results can be briefly summarized as follows:
Experiment I:
At first, it may be profitable to refer that most of
the rates of Fe applied in the chelated form occur beyond
the optimum rate wh~le the reverse is true in case of FeS04·
Accordingly one may expect more adverse effects with
Fe-EDTA than treatments with FeS04 particularly at higher
rates of Fe application. In view of this sight the results,
in general, showed the following:
1. Both of mineral and chela ted sources of Fe (Fe-EDTA
or FeS0
4
) significantly increased sorghum dry weight yield.
2. Iron uptake by sorghum roots, shoots and hence whole
plants was promoted with Fe applications showing a maximum
value at a rate of about 5 ppm Fe in case of Fe-EDTA and
about 20 ppm Fe in case of FeS04·
3. Results show a tendency of Fe accumulation in
sorghum roots when FeS04 was the source of iron supply
perhaps because of precipitation or adsorption of Fe on
root surface or a relatively low mobility of the mineral
.Fe form as compared with the chelated one.
4. The possibility of using FeS04 as a source of Fe
to growing plants was provided that higher rates than those
of chelated iron are needed to compensate the various
mechanisms altering Fe availability or its mobility through
the plants.
. FeS04-tr ated sorghum plants showed higher uptake
of P in whole plants than did the Fe-EDTA treated
ones, but no 5ig ificant differences occurred in shoots.
Calcium ptake by sorghum roots, was increased
with increasing the levels of applied Fe. In both roots
and shoots there existed more calcium uptake by treatments
receiving mineral Fe than those supplied with the chelated
fa rm .
7. The concentration of Mg in sorghum roots was not
affected neitha by iron sources nor rates, while a signiforms,
was obse ved in the shoots.
ficant depressi due to Fe application, in both
8. Both so rces resulted in significant differences
in total mangan uptake. In roots, shoots and whole
plants. Mangan uptake by treatments receiving mineral Fe
increased with ncreasing the rate of applied iron, but
decreased in th receiving the chelated form.
9. A posit va trend was revealed in sorghum shoots
with respect to Fe/Mn ratio with either FeS04 or Fe-EDTA
where it was rna e obvious.
10. A nega ive significant relation occurred in sorghum
shoots between jFeratio and rate of applied Fe-EDTA. The
relation was va y close to significancy in case of FeS04•
The P/Fe ra io was higher in sorghum chlorotic plants
than in the norm 1 ones.
11. The Fe/1n ratio tended to increase gradually
with increasing he rate of applied ironl but only till
the maximum yiel was reached.
12. Its show clearly thatl leachates collected
from the treated pots during the course of the
experiment conta”ned considerable amounts of leached Fel
gradually and si nificantly increased with increasing rates
the other hand, with FeS04 treatmentsl
minute quantitie of leached Fe were recorded indicating
that soluble FeS04 applied was converted into insoluble
form.
13. Iron extracted from cultures by NH40AC pH 4.8 was
increased with increasing the rate of Fe application.
14. Iron fraction extractable by 0.1 N HCl solution
significantly increased with increasing the rate of applied
Fe where the cu t ure s that received FeS04 yielded higher
values than those treated with Fe-EOTA.
Experiment II:
1. Results revealed that occurrence of CaC03 significantly
reduced he dry matter yield of plants while it was
slightly increa ed with Fe applica~ion.
2. Increasi g levels of CaC03 drastically decreased
the concentratio and uptake of iron in roots, shtiots and
whole plants eit er in presence or in absence of iron.
3. Phosphor s concentration and uptake as well in
roots, shoots whole sorghum plants were adversely
affected with increasing levels CaC03·
4. Calcium and magnesium uptake contained by sorghum
roots significantly increased with increasing levels of
CaC0
3, but adverse si9r:ificant trend was observed in plant
shoots.
5. The val es of Mn uptake by sorghum roots, shoots
and whole plant were significantly decreased with application
a f CaCO 3 •
6. Additio of CaC03 tended to decrease the concentration
and total ontent of P, Fe, and Mn in both sorghum
roots and shoot ~
. In sue unbuffered sand culture, calcium carbonate
seems to be an effective factor controlling the concenira-·
tion and uptak of Fe, P, Ca , Mg and Mn that may give
further eviden e to its importance in the Fe chlorosis
phenomenon .
•
Experiment III:
1. Phosph rus uptake by roots, shoots and whole plants
was signifiean ly increased with increasing the rate of P
app liea t ion.
The PIFe ra io was higher in sorghum shoots than in
sorghum roots at all levels of applied P
2. Applicat on of P at a rate of 20 ppm significantll
promoted the tot 1 uptake of Fe. Ca and Mg, but further
rates failed to· ield significant increments.