Autecology and Phytochemistry of Genus Amaranthus in the Nile Delta, Egypt
M.E. Abu Ziada,
The present study deals with the ecology and phytochemistry of three
Amaranthus species, namely: Amaranthus graecizans, A.
lividus and A. viridis. The components of weed vegetation in
the present investigation are classified by cluster analysis into four
groups: group A is codominated by Amaranthus graecizans and
Portulaca oleracea, group B is codominated by Amaranthus lividus
and Cynodon dactylon, group C is codominated by Alternanthera
sessilis and Echinochloa crus-galli and group D is codominated
by Aster squamatus, Conyza bonariensis and Paspalum disticum.
The ordination of the sampled stands applied by Detrended Correspondence
Analysis (DCA) indicated that, the recognized vegetation groups are markedly
distinguishable and having a clear pattern of segregation on the ordination
planes. Also, the application of the Canonical Correspondence Analysis
(CCA) showed that, soil texture, porosity, water-holding capacity, bicarbonate,
sodium, soil reaction (pH), organic matter and electrical conductivity
are the most effective soil variables which correlate with the distribution
and abundance of weed vegetation in the study area. The seed germination
under different levels of salinity, light, temperature and humidity is
studied for the three investigated species. Phytochemically, the mean
values of moisture, ash, total nitrogen, protein, total lipids, soluble
sugars, glucose, sucrose, polysaccharides and total carbohydrates were
determined. The elementary analyses together with qualitative and quantitative
analyses of 16 amino acids were also carried out in the investigated plant
Attention should be paid to increase our knowledge of the best conditions
for propagation of economic plants. In this connection, the importance
of studying plants in their natural habitats, the effect of each habitat
factor upon growth, establishment and distribution must be emphasized.
Many investigators studied the main active constituents of several species
belonging to family Amaranthaceae. Nodeide et al. (1996) reported
that the green leaves of Amaranthus viridis were rich for water,
energy, fats, proteins, minerals, amino acids and carotenoid. In some
species of genus Amaranthus, sixteen phenolic acids were identified
by Sokolowska-Wozniak (1996). Two comarins and three flavonoids were isolated
from Amaranthus paniculatus by Bratoeff et al. (1997). Singh
and Whitehead (1996) mentioned that Amaranthus species are commonly
utilized as vegetable and consumed in Africa, China, India and Italy.
Jale et al. (1999) mentioned that grain amaranth was used as a
partial substitute for barley in diets fermented in artificial rum. Syamdaya
and Naidu (1999) studied the nutritive value of amaranth to sheep. One
can expect the prime importance of the individuals belonging to this family
as a source of substances that can be use for several industrial, medicinal
and fodder purposes.
The present study aims at the description of the weed communities associated
with the studied plant species in their natural habitats by using multivariate
techniques of classification and ordination, analysis of soil samples
to determine the variables controlling the distribution and abundance
of the identified weed communities, seed germination under different environmental
factors and physiochemical investigation to detect the main active constituents
and amino acids in the studied plant species.
MATERIALS AND METHODS
In the present study, ten localities (sites) were chosen in three
governorates of the Nile Delta region (Fig. 1). These
governorates are Kafr El-Sheikh, El-Dakahlyia and Damietta. After regular
visits to the different sites, forty stands representing the apparent
physiognomic variations in the vegetation and environmental features were
used for sampling vegetation of the different habitat types supporting
the growth of Amaranthus graecizans, A. lividus and
A. viridis. The stands were distributed as follows: 7 stands in canal
banks, 7 stands in orchards and 26 stands in cultivated lands. The sampling
processes have been carried out during the years 2004-2006.
||Map of the Nile Delta region showing different localities (sites)
as indicated by (●) in the study area
The density and plant cover of each species have been estimated in each
stand using quadrat of 5 m2. The relative values of density
and cover were calculated for each species and summed up to give an estimate
of its importance value (IV) in each stand, which is out of 200. The Nomenclature
and identification of the species was according to Tackholm (1974) and
Soil sample was collected from each stand at a depth of 0-25 cm for physical
and chemical analyses. Soil texture was determined using the hydrometer
method, while the water-holding capacity was estimated using the Hilgard-Pan
box method of Piper (1947). Oxidizable organic carbon was estimated using
the Walkely and Black rapid titration method (Black, 1979). The percentage
of calcium carbonate was determined by addition of 100 mL 1 N HCl to 5
g soils and the excess of acid titrated against 1 N NaOH. Soil salinity
(EC) and soil reaction (pH) were estimated in 1-5 water extract using
the conductivity and pH meters, respectively. Chloride was determined
by titration against N/35.5 silver nitrate, while sulphate was estimated
gravimetrically using 5% barium chloride. Estimation of carbonate and
bicarbonate were carried out by titration against 0.1 N HCl. The cations
Na+, K+ and Ca++ in the soil solution
were estimated using flame photometer as described by Allen et al.
Two trends of multivariate analysis of vegetation were applied, namely
classification and ordination. Both trends have their merits in helping
to understand the vegetation and environmental phenomena. Two-Way Indicator
Species Analysis (TWINSPAN-a FORTRAN Program) was used for classification
(Hill, 1979; Gauch and Wittaker, 1981), while the ordination techniques
applied were the Detrended Correspondence Analysis (DCA) and Canonical
Correspondence Analysis (CCA) using CANOCO- a FORTRAN Program (Ter Braak,
1986, 1988). The relationships between the vegetation gradients and the
environmental variables can be indicated on the ordination diagram produced
by canonical correspondence analysis (CCA biplot), on which points represent
species and arrows represent environmental variables. The statistical
treatments applied in the present study were according to Snedecor and
Cochoran (1968) and Anonymous (1993).
Germination experiments were conducted to find out the effect of salinity
levels, light and dark, temperature and water spray (humidity) on the
rate of seed germination of the three different Amaranthus species.
For the first three experiments, germination was tested in equal sized
Petri-dishes (13 cm) containing double layered filter paper moistened
with distilled water or with different test solution. For each treatment,
one hundred seeds were sown in each dish and two replicates Petri dishes
were used. In case of water spray experiment, equal sized pots (14 cm
height and 14 cm diameter) were filled with clean sand and one hundred
seeds also sown at 0.5 cm depth.
Concerning the phytochemical analysis, the plant samples were handly
cleaned, separated into roots, stems and leaves, air-dried, ground to
fine powder and kept in a well stopper vessels to be ready for different
phytochemical investigations. The mean values of moisture, ash, water-soluble
ash, acid-insoluble ash and total lipid content were investigated according
to AOAC (1970) methodology. Soluble sugars, glucose, sucrose, polysaccharides
and total nitrogen content were estimated according to Naguib (1963, 1964).
The protein content was determined colorimetrically as described by Waslein
(1975). The preliminary phytochemical screening was carried out following
the methods described by Wall et al. (1964), Claus (1967) and Markham
(1982). Hundred grams of each plant powder was subjected to extraction
with successive solvents using AOAC (1970) methodology. The macro and
microelements were determined by atomic absorption spectrophotometer using
the methods described by Allen et al. (1974). The identification
and quantitative determination of amino acid in the plant powders were
carried out using amino acid analyzer (Model, LC 3000) as described by
Moore and Stein (1958).
Classification of stands: The dendrogram obtained from cluster analysis
based on the importance values of 65 species recorded in 40 sampled stands
in the study area indicated the distinction of four vegetation groups
(Fig. 2, Table 1). Group A comprises
12 stands codominated by Amaranthus graecizans (IV = 37.70) and
Portulaca oleracea (IV = 29.42). The important species in this
group include Sonchus oleraceus (IV = 13.99), Cyprus rotundus
(IV = 13.98) and Dactyloctenium aegyptium (IV = 11.72). Group
B includes 17 stands codominated by Amaranthus lividus (IV = 34.42)
and Cynodon dactylon (IV = 26.29). In this group, the important
species are numerous such as: Sorghum vigratum (IV = 18.51),
Cyprus rotundus (IV = 14.42), Ammi majus (IV = 14.31),
Convolvulus arvensis (IV = 13.87) and Bidens pilosa (IV =
10.25). Group C includes 9 stands codominated by Alternanthera sessilis
(IV = 36.53) and Echinchloa crus-galli (IV = 27.15). The
important species in this group are Eclipta alba (IV = 18.29)
and Phyla nodiflora (IV = 10.25), group D consists of 2 stands
codominated by Aster squamatus (IV = 40.18), Conyza bonariensis
(IV = 27.67) and Paspalum distichum (IV = 31.04). The important
species in this group comprise Bassia indica (IV = 26.65),
Phragmites australis (IV = 25.94), Pluchea dioscoridis (IV
= 15.50) and Alternanthera sessilis (IV = 13.75).
||The dendrogram resulting from cluster analysis of 40 sampled stands
representing habitat types of some Amaranthus species. The
dashed line denotes the level at which the dendrogram yields four
distinct vegetation groups
Ordination of stands: The ordination of the sampled stands which
obtained by detrended correspondence analysis (Fig. 3)
indicated that, the vegetation groups yielded by cluster analysis are
markedly distinguishable and having a clear pattern of segregation on
the first and second axes of the ordination planes. Group A codominated
by Amaranthus graecizans and Portulaca oleracea is separated
at the central part of the DCA diagram. Group B codominated by Amaranthus
lividus and Cynodon dactylon is segregated at the left side
of the ordination diagram. On the other hand, group C codominated by Alternanthera
sessilis and Echinochloa crus-galli is segregated at the right
side of the DCA diagram. It is clear that, groups B and C are separately
segregated at both sides of group A, where these three groups (A, B and
C) are distinctly located on the positive and negative sides of the first
and second axes of DCA diagram. However, group D codominated by Aster
squamatus, Conyza bonariensis and Paspalum distichum is
separated at the upper most right positive side of DCA diagram.
Soil analysis: It has been found that, most of the soil characteristics
showed a little variation between the different groups of the sampled
stands. The soil texture is mainly formed of coarse fraction (sand) and
partly of fine fractions (silt and clay). The mean values of water-holding
capacity and soil porosity are obviously comparable in all groups. The
mean values of calcium carbonate content are higher in groups C (10.89%)
and B (7.88%) than in groups A (5.32%) and D (3.75%), while those of organic
carbon content are higher in groups A (0.33%), B (0.29%) and D (0.26%)
than in group C (0.14%). The pH values indicated that, the soil reaction
is neutral or slightly alkaline and it ranged between 7.38 in group A
and 7.80 in group D (Table 2). The Electrical Conductivity
(EC), chloride and sulphate attained higher mean values in groups C and
D than in groups B and A. The soluble bicarbonate is detected in traces.
The concentration of extractable cations: Na+, K+
and Ca++ attained their highest mean values in group D (1465.00,
494.25 and 111.70 ppm, respectively).
||Mean value and coefficient of variation of the importance value
of species in the vegetation groups resulting from cluster analysis
of the sampled stands
||Detrended Correspondence Analysis (DCA) ordination of the 40 sampled
stands with four cluster groups
||Mean value and standard error (±) of the different soil variables
in the sampled stands representing the four vegetation groups obtained
by cluster analysis in the habitat types of Amaranthus species
|WHC: Water-Holding Capacity, EC: Electrical Conductivity
The correlation between vegetation and soil variables: The relationship
between vegetation and edaphic variables is indicated on the ordination
diagram produced by Canonical Correspondence Analysis (CCA) of the biplot
of species-environment as shown in Fig. 4. It is obvious
that, the values of clay, bicarbonate, porosity, sodium cation, sand fraction,
water-holding capacity, organic matter, soil reaction (pH) and electrical
conductivity are the most effective soil variables which showed a distinct
significant correlations with the first and second axes of the CCA biplot
Seed germination: The seed germination capacity of Amaranthus
species is investigated under different levels of salinity, light
and dark, temperature and water spray (Table 3). The
effect of different salinity levels on the seed germination of the three
studied Amaranthus species showed that, the rate of germination
is reached its highest values of 97% with distilled water treatment. When
the low salinity levels of 0.02, 0.03 and 0.04 M NaCl solution are used,
the percentages of germination attained 92, 77 and 57% for A. graecizans,
86, 80 and 57% for A. lividus and 94, 80 and 68% for A. viridis,
respectively. But at salinity levels of 0.1, 0.2, 0.3, 0.4 and 0.5 M NaCl
solutions, the percentages of germination decreased gradually and the
minimum rate of germination at 0.5 M NaCl solution attained 9% for A.
graecizans and 5% for both A. lividus and A. viridis.
The results obtained from the effect of light and darkness on seed germination
of the studied species showed that, the highest values of germination
attained 90, 98 and 70% under continuous light for A. graecizans,
A. lividus and A. viridis, respectively. The minimum numbers
of germinated seeds are 65% for A. graecizans and 58% for both
A. lividus and A. viridis. The seeds of the investigated
plant species had the capacity of germination between 20-40°C for
both A. lividus and A. viridis and 25-40°C for A.
graecizans. It is evident that, the optimum temperature for the seed
germination of the three selected species are 35°C (49%), 40°C
(98%) and 30°C (78%) for A. graecizans, A. lividus and
A. viridus, respectively. It is also obvious that, the decreased
amount of water spray is badly affected on the rate of seed germination
of the three plant species. In case of A. graecizans, seed
germination is started at 10 mm water spray being 34%. At 5 and 10 mm
water spray, both A. lividus and A. viridis seeds are failed
to germinate and started at 15 mm water spray being 23 and 46%, respectively.
At the highest level of applied water spray (saturated), the germination
percentages reached 75, 90 and 96% for the seeds of A. graecizans,
A. lividus and A. viridis, respectively.
||Canonical Correspondence Analysis (CCA) ordination diagram with
soil variables represented by arrows. The indicator and preferential
species are abbreviated to the first three letters of each of the
genus and species
||No. of germinated seed of Amaranthus species under different
levels of temperature, water spray (humidity), salinity and light/dark
||Mean value of chemical constituents in different organs of Amaranthus
||A preliminary phytochemical screening of active constituents of
the different organs of Amaranthus species
|+ve: Present, -ve: Absent
Determination of chemical constituents: The data analysis showed that,
A. lividus contained a relatively high percentage of the mean values
of moisture content (9.51%), ash content (20.67%), water-soluble ash (11.17%),
total protein (214.8 mg/100 g dry wt.) and total lipid (13.73%). A.
graecizans contained a relatively high percentage of the mean values
of acid insoluble ash (2.45%) and total carbohydrates (196.5 mg/100 g
dry wt.). The highest mean value of total nitrogen content (271.14 mg/100
g dry wt.) is recorded in A. viridis (Table 4).
Preliminary phytochemical screening: The presence of alkaloids,
carbohydrates, flavonoids, sterols and tannins in all organs of the studied
species. Saponins is detected only in the leaves of both A. lividus
and A. viridis as well as in the stems of A. viridis. Sulphates
are recorded in all organs of the studied species except in the leaves
of A. graecizans. Chlorides are recorded in all investigated plant
organs except in the leaves and roots of A. graecizans (Table
||Extraction of the different fractions of Amaranthus species
with successive organic solvents
||Mean value of amino acid concentrations (μg mg<-1)
in Amaranthus species
||Variation in cation concentrations (K+, Mn++,
Cu++, Na+, Mg++, Fe++,
Ca++, Zn++ and Cd++) of root, stem
and leaf of Amaranthus species, AG: Amaranthus graecizans,
AV: Amaranthus viridis, AL: Amaranthus lividus
Extraction with successive solvents: The results indicated that,
the leaves of A. lividus attained a relatively high percentages
of total extractives being 96.45 g%, while the lowest one (15.25 g%) is
recorded in the roots of A. graecizans (Table 6).
Elementary analysis: It is clear that, the highest values of potassium
ion concentration (112.6 mg/100 g dry wt.), iron (198.5 mg/100 g dry wt.),
copper (1.17 mg/100 g dry wt.) and cadmium (0.19 mg/100 g dry wt.) are
recorded in A. graecizans. The sodium ion concentration (276.74
mg/100 g dry wt.), calcium (93.14 mg/100 g dry wt.), magnesium (3.34 mg/100
g dry wt.), manganese (0.45 mg/100 g dry wt.) and zinc (2.03 mg/100 g
dry wt.) are recorded in A. lividus (Fig. 5).
Amino acids investigation: The data obtained from the amino acids
investigations are shown in Table 7. Fifteen amino acids
are detected in each of the studied species, namely: aspartic, threonine,
serine, glutamic, proline, glycine, alanine, valine, leucine, isoleucine,
phenylalanine, tyrosine, histidine, lysine and arginine, in addition to
cystine which is detected only in A. graecizans.
Amaranthus is a cosmopolitan genus comprises almost 65 species,
distributed in the tropical, subtropical and warm regions of the world
(Boulos, 1999). In the present study, the chosen species, namely: Amaranthus
graecizans, A. lividus and A. viridis have high medicinal
and nutritive values (El-Morsy, 2001). The habitat types supporting the
growth of these plants are mainly ruderal habitats including orchards,
cultivated lands and canal banks, which predominate in the agricultural
areas of the Nile Delta region. According to the map of the world distribution
of the arid regions (UNESCO, 1977), in the Nile Delta, summer is warm
with an average temperature ranges between 20 and 30°C, while winter
is mild with an average temperature ranges between 10 and 20°C. Most
of rainfall occurs during winter.
The weed vegetation is classified by cluster analysis into four groups,
each group comprises a number of stands which are similar in their vegetation
and characterized by dominant and/or codominant species as well as by
a number of indicator and/or preferential species. The recognized groups
are: Group A is codominated by Amaranthus graecizans and Portulaca
oleracea, group B is codominated by Amaranthus lividus and
Cynodon dactylon, group C is codominated by Alternanthera
sessilis and Echinochloa crus-galli and group D is codominated
by Aster squamatus, Conyza bonariensis and Paspalum
distichum. These groups may be related to alliance of Digitarietalia
sanguinalis described by Zohary (1973). The associations of weed vegetation
recognized in the present study might be similar to those described by
El-Fahar (1989), El-Ashri (1996) and Omar (2006). The ordination of the
sampled stands by DCA indicated that, group A (Amaranthus graecizans
and Portulaca oleracea) and group C (Alternanthera sessilis
and Echinochloa crus-galli) are more closely related to each other
than group B (Amaranthus lividus and Cynodon dactylon) and
group D (Aster squamatus, Conyza bonariensis and Paspalum
distichum). This may be due to the distinct similarities of the floristic
composition in these vegetation groups. The application of CCA biplot
between the vegetation groups and soil variables indicated that, fine
fraction (clay), bicarbonate, porosity and sodium ions are the most effective
soil variables controlling the distribution and richness of the weed vegetation
in the study area, followed by coarse fraction (sand), salinity (EC),
water-holding capacity and soil reaction (pH). These findings are in accordance
with those of Mashaly and Awad (2003) and Omar (2006).
With regard to seed germination, it is denoted that, Amaranthus graecizans
is more salt tolerant than the other two species, also A. viridis
is more sensitive for salinity than A. lividus. The seed germination
showed distinct sensitivity to continuous darkness, while in continuous
light, the seeds attained their highest values of germination. These observations,
may give an indication that these species are long-day plants. The seeds
had the capacity to germinate between wide ranges of temperature. This
may explain why these species prefer to flourish at early and mid-summer.
The percentage of seed germination of the studied species increased with
rise of water spray or humidity level.
Dealing with the phytochemical investigation, it is notable that the
leaves of the studied species are usually higher in their chemical constituents
than the stems and roots. The highest value of total protein content was
observed in A. viridis, that of total lipid in A. lividus
and that of total carbohydrates in A. gracezans. It may be concluded
from the results of the preliminary phytochemical screening that Amaranthus
plants may be used as sources of potentially useful products. and
that they deserve further investigation to explore the nature of these
products. The results of amino acids investigation provide evidence that
the genus Amaranthus being rich in proteins with essential amino
acids like lysine which is considered as a good candidate for food supply
both as grain crop and as vegetable. In this connection, Amarantin as
storage protein of Amaranthus was isolated by Romero et al.
(1996). Sena et al. (1998) reported that, A. viridis
being an excellent source of protein. The phytochemical results in the
present study, seemed to be comparable with those obtained by Raja
et al. (1997), El-Morsy (2001) and Omar (2006). Consequently, the
selected plant species appeared a promising weeds as a renewable natural
resources and raw materials for different uses in industrial, food, forage
and pharmaceutical purposes.
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