الفهرس 
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Abstract
The present investigation was carried out in an attempt
to add some informatiom about the response of AzolIa pinnata
and Spirodela polyrhiza to variable concentrations of some
essential nutrient elements such as phosphorus, calcium and
cobalt added to the nutrient media. Also, the effect of some
different levels of cadmium and lead as a toxic heavy metals
which may contaminat the natural a queous media of these two
genera was studied under laboratory conditions.
To approach this aim, two laboratory experiments were
carried out under semi-controlled conditions which include:
A. Comparative studies on the effects of some concentrations
of phosphorus, calcium and cobalt on the
growth behaviour and mineral accumulation in both
studied genera as well as the contents of sugars,
chloroplast pigments and amino acid fractions.
B. Comparative studies on the toxic effects of some
concentrations of Cadmium and lead on growth
behaviour, mineral contents and the changes in
chloroplast pigments, sugars and amino acid fractions
of the two studied genera.
The results obtained could be summarized as follows:
A) Experl.ent I:
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1- Application of different P, Ca and Co levels seemed to
regulate the growth of Azolla and Spirodela plants.
Such regulation varied greatly within the tested plant
genera and according to the examined element and its
level.
2- The application of different P, Ca and Co levels affected
greatly the concentrations and the uptake of N,
P, K, Ca, Hg, Na, Fe, Hn, Cu and Zn by Azolla and
Spirodela plants. This effects differed greatly within
the tested plant genera and varied according to the examined
element and its level. This may indicate that
the response of the used genera to the application of
different levels of P, Ca and Co was greatly differed
and that may be related to the variable inheritance
tendency.
3- The proportion and the distribution of different elements
in AzalIa and Spirodela tissues was greatly influenced
by variation of P, Ca and Co application
levels.
4- Photosynthetic pigment concentrations changed greatly
with the variable change in the levels of P, Ca and Co
in AzalIa and Spirodela plant tissues. Such change
seemed to affected the accumulation of sugars and amino
acid accumulations in plant tissues. The degree of such
change was greatly differed between the studied genera.
5- Sugars and total free amino acids contents in AzalIa
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and Spirodela plant tissues were
the variable concentrations of P,
greatly affected by
Ca and Co levels affeeted
the plant metabolism which varied according to
the inheritance tendency and the variable response of
the used plant species.
6- The proprtion of reducing - to non-reducing sugars was
changed greatly by the variable applications of P, Ca
and Co in Azolla and Spirodela .
7- The application of P, Ca and Co seemed to regulate the
accumulation of different amino acid fractions in
AzalIa and Spirodela plant tissues.
8- The variable changes in the accumulation of different
nutrient elements, and different tested organic matters
in AzalIa and Spirodela plant tissues as related the
variations in P, Ca and Co levels take a role in plant
growth responces.
The dominant amino acids in Azolla are:
Glutamic + Alanine followed by aspartic acid, leucine,
arginine, lysine, Phenylalanine, isoleucine, glycine,
serine, proline, threonine, valine, cystine, methionine
and finally histidine in deascending order.
The inhibiting effect of lack of (P) or (Ca) on
total a~ino acids resulted mainly fro~ the concentration
of glutamic + alanine. Also (P) deficiency minimized
most of the various amino acids, but (Ca)
deficiency minimized only glycine, isoleucine,
threonine, serine, cystine and phenylalanine. The absence
of (Co) slightly altered the amino acids picture.
With regard to Spirodela plants, the absence or the
excess of (P), (Ca), or (Co) decreased the concentrations of
the total amino acids, but shortage of (P) was superior in
this respect followed by (Co) and (Ca).
The most abandant amino acids in $pirodela are glutamic
+ alanine followed by: aspartic or leucine, arginine,
cystine, threonine, valine, phenylalanine, isoleucine,
proline, glycine, histidine, serine and cystine in deascending
order.
The negative effect of (P) deficiency occurred on the
concentrations of glutamic + alanine, leucine, threonine,
serine, methionine, cystine, lysine, arginine, phenylalanine
and histidine. Lack of (Co) minimized the concentrations of
glutamic + alanine besides threonine, methionine, cystine,
lysine, arginine and histidine. The other amino acids
slightly increased or unchanged.
B- Experiment II:
1- Observation during growth, different concentrations of
(Cd) or (Pb) changed the normal light green appearance
into yellowish one. The proportional chlorosis appearance
increased progressively in the frond with
icreasing plant age and also with increasing (Cd) or
(Ph) levels. Also (Cd) treatments seemed to enhance the
abscission of lateral branches from the main axis of
the mother fronds more than did (Ph) treatment. So both
Azolia and spirodeia could be used as an excellent
biological indicators or monitors for (Cd) or (Pb)
water pollution, however, Spirodela plants are more
sensitive than Azolla in this respect.
2- Growth, the different levels of (Cd) or (Pb) decreased
significantly AzalIa pr Spirodela fresh weight and
daily percentage was also decreased. However number of
plants per one gram fresh weight was increased and the
reduction increased with increasing (Cd) ar (Pb)
concentrations. Also lead had less toticity on AzalIa
growth comparing to (Cd) effect.
Azolla plant could absorb (Cd) from the nature
media easily than that absorbed by Spirodela. Also under
the nature conditions in which AzalIa servives such
plant may be considered as (Cd) sink and could be used
for removing such element from the very low contaminated
polutant media.
3- Different levels of (Cd) or (Pb) decreased mostly the
concentrations of H, P, K, Ca, Hg, Na, Hn and Cu in
both AzalIa and Spirodela, but (Fe) increased with increasing
of (Cd) concentration. Also in case of
Spirodela, (Mn) and (Zn) concentrations increased with
increasing (Pb) concentration.
4. Total accumulation of some nutrient elements:
I- In Azolla plants:
a. The different levels of (Cd) were very harmful to
the process of N- fixation and the reduction observed
in N-accumulation increased with
concentration.
b. The different levels of (Pb) were less harmful to Nincreasing
(Cd)
fixation than those of (Cd). Thus, the lower (Pd) concentrations
(10,15 and 25 PPm.) increased of the toatal
N- accumulated in plant tuisues, while the high (Pb)
concentration (40 PPm.) decreased thise accumulation
and this decrease was less than that caused by (Cd).
c. Different levels of (Cd) or (Pb) decreased the accumulations
and/or the uptake of the different essential
elements, but (Pb) was less harmful in this
respect than (Cd). The only exception in this respect
was (Fe) which showed continuous increase especially
under (Cd) treatments.
d. The different levels of both (Cd) or (Pb) did not
effect the proportion but affected the balance of the
essential elements in AzalIa tissues.
2) In SDirodela plants:-
a) The effect of (Cd) or (Pb) levels on the amounts of
the essential elements was less in case of Spirodela
than in AZalIa and also the effect of (Pb) was less
than that of (Cd) in this respect.
b) The applied rates of (Cd) or (Pb) caused troubles in
mineral accumulation and their uptake.
c) Cadmium and lead reduced (Ca) accumulation in both
Splrodela and AZalIa and Such reduction was proportional
to the increase in (Cd) or (Pb) levels. Also
(Cd) was more effective than (Pb) in this respect.
5- The different levels of (Cd) or (Pb) decreased the concentrations
of the photosynthetic pigments In both
AzalIa and Spirodela .. SUch reduction was great with increasing
concentrations of (Cd) or (Pb). Also, (Cd) was
more effective than (Pb) in this respect.
6- Sugars, the different levels of (Cd) or (Pb) reduced
greatly the sugar accumulation in both AzalIa and
Spirodela, and (Cd) ”as more effective than (Pb).
All the tested rates of (Cd) or (Pb) disrurbed the
proportion of reducing- or oon- reducing sugars as related
to the total sugar amounts.
7- Host of the different (Cd) or (Pb) levels increased the
concentrations of f:ree amino acids In both AZalIa and
Spirodela and (Cd ) sel!aed to be more effective than
(Pb) .
The different levels of (Cd) lowered the accumula-
tion of free amino acids in Azolla, while (Pb) enhanced
such accumulation. On the other hand, the different
levels of (Cd) or (Pb) enhanced such accumulation in
Spirodela.
8- In both AzolIa and ~pirodela the total amino acids concentrations
(mg/g dry matter) decreased continuously
with increasing the rates of (Cd) or (Ph). This reduction
was observed with every amino acid tested.
In case of Azo]~ the different (Cd) or (Pb)
levels changed the concentrations of most amino acids
and the most pronounced reduction was obtained with
glutamic + alanine, leucine, lysine and Phenylalanine,
amino acids were una.ffectedor may increased 51 ightly.
In case of Spirodela, nearly all the tested omino
acids decreased with increasing the concentiation of
(Cd) or (Pb).