Alfalfa has been proven to be one of the most productive forage crops and also
one of the most effective man-planted vegetations to conserve soil and water
and to fix soil nitrogen. Its interest were: Forage very rich in proteins, its
contribution of the fertility of the ground. The various possible uses of Lucerne
forage are direct animal feeding and also industrial treatments: Dehydratation
and now protein extraction, perhaps fiber extraction. The improvement of these
characters is necessary for the feeding of highly productive animals. The
M. sativa complex shows a large genetic variability due to both natural
and human selection under various climates and locations. It`s an autotetraploid,
with 2n = 4x = 32 and allogame species. The genetic progress in this species
is slow because of its autotetraploidy, allogamy synthetic structure of the
varieties. This species is characterized by a great morphological and agronomic
variability (Julier et al., 2000) adopted in the
programs of genetic improvement and the development of the cultivars with a
very significant output (Julier et al., 2000).
Several researchers were discussed around taxonomic classification the alfalfa
(Medicago sativa). Lesins and Lesins (1979) consider
that the complex Medicago sativa gathers three pennies species: Under
species sativa which are characterized by flowers violets with pods without
spines, under species falcata which is characterized by yellow flowers with
pods with spines and under species glomerata which is characterized by flowers
violets and pods with épines. Le Medicago kind is well represented in Tunisia.
It constitutes a genetic inheritance extrémement richeet divérsifié (Seklami
and Hansen, 1990). Contrary to the annual alfalfas, the culture of the perennial
alfalfa is not new in Tunisia. It is very old on the level of the oases of the
country (Le Houerou, 1969). It is the fodder plant most
employed in irrigation. Its culture in dryness is a recent practice going back
only to one score of years (Le Houerou, 1965).
MATERIALS AND METHODS
Plant material: Thirty five populations of the cultivated alfalfa
(Medicago sativa L.) were involved in the study, including 20 local
originating in the Tunisian South and 15 introduced (Table
This study was carried out in experiment field of Institute Arid Area
of Medenine Tunisia. Seeds of different genotype were sowed in April 2005.
The measurements were carried two month after this date. The collect of
vegetable material was realised in July 2005. The young leaflet were extracted,
dried and conserved at 40°C for other use.
Morphological traits: The study of morphological variability is
carried using 9 quantitative descriptors chosen according to the list
of descriptors IPGRI. These parameters can be divided into vegetative
parameters such as the length of the central leaflet (LFC), the width
of the central leaflet (lFC) and the leaf area (SFC), the No. of primary
branches (NBP) and the length of the plant (LP); morphological parameters
in particular the No. of the flowers by plant (NFP) and No. it pods by
plant (NGP) and finally certain parameters reflecting the fodder output
which one can quote the dry weight of the stems (PST) and the dry weight
of sheets (PSF).
The measurements are related to a cycle of development.
|| List of different populations of cultivated alfalfa
Preparation of the extract vegetal
||Heat 1 g of powder at 500°C for 4 h
|| Add 4 mL distilled water and 1 mL of hydrochloric acid
|| Filter the mixture and to adjust with 100 mL by distilled water
This solution will constitute the basic extract for the analysis of sodium
(Na+), potassium (K +) and phosphorus (P).
Sodium content and potassium: The contents of minerals are determined
by photometer with flame. One prepares the standard solutions starting
from solutions mothers, of concentration 1000 ppm.
Phosphorus content: The phosphorus content is determined by spectrophotometer.
One prepares the standard solutions starting from a solution mother H2PO4.
RESULTS AND DISCUSSION
Morphological parameters: The values of the descriptors studied
for the various populations are shown in Table 2 which
enables us to note that:
||The number of the primary branches (varies between 5 and 8) as well
as the length of the plant (varies between 53 and 87 cm) do not show
a variability between the local populations and those introduced:
|| The length of central leaflet varies between 2.6 and 3.45 cm, that
of the width lie between 1.17 and 2.22 cm and the leaf area vary between
2.03 and 5.15
|| The number of inflorescences (ranging between 10 and 200) as well
as the number of the pods (located between 16 and 545) are very significant
at the local and weak populations with means at the introduced populations
||The dry weight of the sheets (which varies between 3 and 14 g) as
that of the stems (which is located between 2 and 6 g) is shown more
interesting at the local populations than that introduced
| Quantitatively tested traits
Hierarchical classification by combining all the parameters: The
various studied populations are arranged in 4 groups by combining the
vegetative and reproductive parameters (Fig. 1).
Group 1 (G1): With poor yield. It includes the total of introduced
populations Magali, African, Ameristand 801S, Mamuntanas, Cossouls, Melissa,
Demnat 203, ABT, Prosementi, Rich2, Ecisilia, Siriver, Tamantit, Sardi
and Erfoud1; Some local`s populations: Chenchou, Ghannouch, Chenenni1,
Stiftimia, Douz, Zerkine, Elgolaa and Bouhlel. The characteristics of
this group are: the central leaflet is characterized by a fairly significant
length from 2.35 to 3.5 cm, an average width of 1.12 to 2.53 cm and a
surface fairly significant ranging between 2.03 and 3.93 cm2;
an average height (53 to 77 cm); a number of the inflorescences (10 to
56) and pods (varying from 12 to 67) weak; a dry weight of the stems (between
1.5 and 3.75 g), that of the sheets (2.9 with 5.32 g) weak.
Group 2 (G2): It includes some local`s populations: Essdada, Jersine,
Metwia, Kattana, Chenenni 2, Limaguess, Chenenni 3, Dgach and Nouael.
The characteristics of this group are: a height is very significant (64
with 87 cm); LE central leaflet is characterized by a significant length
ranging between 2.8 and 3.5 cm, an also significant width from 1.4 to
1.8 cm and a significant surface located between 2.7 and 4.2 cm2;
a number of the inflorescences (65 to 179) and pods (250 and 359) significant;
a dry weight of the stems (2.26 with 4.36 g), that of the sheets (8.5
and 14 g) significant.
|| Hierarchical classification of different populations
based on morphologicals traits
Group 3 (G3): It includes 3 local populations: Tboulbou, Hamma
Jerid and Zaafarane. The characteristics of this group are summarized
as follows: a significant height (72 with 82 cm); the central leaflet
is characterized by a significant length ranging between 2.6 and 3.3 cm,
its width are also significant and vary from 1.42 to 2.22 cm and its surface
significant is located between 3 and 5.13 cm2; a number of
the inflorescences (111 to 206) and that of the pods (442 to 545) very
significant; a dry weight of the stems (3.2 and 6.75 g), that of the sheets
(11 and 15.9 g) very significant.
Analyze factorial in principal components (ACP): The factorial
analysis in principal components is a procedure making it possible to
measure the performance of the various parameters. The percentage of inertia
of various axes is shown in Table 3.
The selected plan is formed by the two axes F1 and F2
which provide 71% of total information (Fig. 2).
Populations: Zaafarane, Teboulbou, Hamma Jerid, Nouael, Chenenni
2, Chenenni 3, are correlated with the positive part of F2
axis. This group is characterized thus, by a significant length of plant,
length of central leaflet, surfaces central leaflet and dry weight of
stems; an average No. of primary branches; width of central leaflet means;
very high numbers of inflorescences and pods by plant.
|| Superposition of different populations and the quantitative
traits with the two axis F1 et F2; P-P1: Kattana; P-P2: Chenchou;
P-P3: Cheninni 1; P-P4: Cheninni 2; P-P5: Cheninni 3; P-P6: Teboulbou;
P-P7: Metwia; P-P8: Ghannouch; P-P9: Zerkine; P-P10: Essdada; P-P11:
Bouhlel; P-P12: Degach; P-P13: Hamma jerid; P-P14: Zaafarane; P-P15:
Nouael; P-P16: Jerzinze; P-P17: El golaa; P-P18: Limaguess; P-P19:
Douz; P-P20: Stiftimia; P-P21: Sardi; P-P22: Ecotiposiciliano; P-P23:
ABT; P-P24: Ameristand; P-P25: Erfoud 1; P-P26: Melissa; P-P27: Siriver;
P-P28: Rich 2; P-P29: Demnat 203; PP-30: Tamantit; P-P31: Magali;
P-P32: Magali; P-P33: Mamuntanas; P-P34: Cossouls; P-P35: Africaine;
NG/P: Nuber of Pods by Plants; PST: Dry weight of stems; PSF: Dry
weight of sheets; LP: Length of plant; NI/P: No. of inflorescence
by plant; SFC: Area of central leaflet; LFC: Length of central leaflet;
lFC: Width of central leaflet
The populations Dgach, Kattana, Bouhlel, Essdada, Chenenni 1, Douz, Stiftimia,
Cheneni 3, Ghannouch, Jersine and Limaguess are concentrated of the negative
part of F1 axis. This group is characterized by: Significant length of
the plant and length of central leaflet; a lower No. of primary branches;
a high No. inflorescences and pods by plant.
Following populations: Sardi, Esicilia, ABT, Ameristand, Erfoud, Melissa,
Siriver, Rich 2, Demnat 203, Tamentit, Magali, Prosemet, Mamuntanas, Cossouls,
Africane, Chenchou and Elgolaa are concentrated to the positive part of
the F1. This group of populations is characterized by: low
length of plant, low No. primary branches, No. inflorescences and pods
by plant; low length and width of central leaflet; average surface central
leaflet; low dry weight of the stems and the sheets.
Sodium contents: The sodium contents of the various populations
are represented by Table 4 which shows that the sodium
contents vary between 06 and 0.159%.
Hierarchical classification: The sodium contents are analyzed
by the software SPSS which group all the populations in 3 groups carried
by the dendrogramme from Fig. 3.
||Sodium percentage for the different populations of Lucerne
|| Hierarchical classification with Na+ composition
Group 1 (G1): Included: Erfoud, Cossouls, Metwia, Degach, EcotipoSiciliano,
Sardi, Melissa, Ghannouch, Douz, Siriver, Demnat 203, Erfoud, Cossouls,
Metwia, Essdada, Zaafarane, Kattana, Ameristand 801S, Prosementi, Jersine,
Staftimia, Cheninni 2 and Hammajerid which are characterized by high percentages
of sodium (ranging between 0.092 and 0.139%).
Group 2 (G2): Included populations: Chenenni1, Rich 2, African,
Bouhlel, Nouael and Tamantit which are characterized by low contents (located
between 0.061 to 0.08%).
Group 3 (G3): Included only one population, it is Mamuntanas which
is characterized by content very high sodium (0.159%).
Potassium contents: The potassium contents for the various
populations are shown in Table 5, the potassium contents
varied between 1.08 and 2.64%.
||Potassium percentage (%) for the different populations
|| Hierarchical classification with K+ composition
Hierarchical classification: The potassium contents are analyzed
by the software SPSS which made it possible to group the various populations
in 3 groups carried by the dendrograme of Fig. 4.
Group 1 (G1): Gathers the populations: Prosementi, African, Dgach,
Zaafarane, Melissa, Jersine, EcotipoSicilia, Metwia, Bouhlel, Hamma jerid,
Nouael, Stiftimia, Essdada, Limaguess, Cossouls, Zerkine and Elgolaa,
which are characterized by potassium contents (ranging between 2.16 and
Group 2 (G2): Included: Chenenni 3, Mamuntanas, Ghannouch, Sardi,
Tamentit, Magali, Chenenni 2, Douz, Rich 2, Tboulbou, Ameristand 801S,
Demnat 203, Kattana, Erfoud 1, Siriver, Chenenni1 and Chenchou, of which
average contents potassium (ranging between 1.32 and 2.05%).
Group 3 (G3): Included only one population; it is ABT805 which
is characterized by the lowest potassium content (1.08%).
Phosphorus contents: The phosphorus contents for the various populations
of alfalfa are shown in Table 6 which shows that the
phosphorus contents at these populations vary between 0.06 and 0.259%.
Hierarchical analysis: The phosphorus contents are treated by
software SPSS version 12.0, the various populations were arranged in three
groups carried by the dendrogramme from Fig. 5.
Group 1 (G1): Formed by Tamentit, Cossouls, Bouhlel, Elgolaa,
Ghannouch, Degach, Stiftimia, Tboulbou, Chenenni 2, Chenenni 3 and Zaafarane
Limaguess, Prosemet, Essdada, Kattana, Esicilia, Mamuntanas, Melissa,
Ameristand 801S, Rich 2, Erfoud 3, Jersine, Siriver, Hamma jerid, Nouael,
Sardi, Chenenni1, Magali, Chenchou and Metwia which are characterized
by average contents phosphorus (vary between 0.175 and 0.2%).
Group 2 (G2): Formed by only two populations which are
ABT 805 and Demnat 203 and which is characterized by low contents of phosphorus
(ranging between 0.06 and 0.07%).
||Hierarchical classification with phosphorus composition
|| Phosphorus percentage for the different populations
Group 3 (G3): Formed by three different populations which are:
African Zerkine, Douz and which is characterized by high percentages of
phosphorus (ranging between 0.24 and 0.274%).
Combination of various minerals: Software SPSS 12.0 allows the
classification of the various populations studied by combining three minerals
according to the dendrograme of Fig. 6, presenting 3
Group 1 (G1): Included: Erfoud 3, Siriver, Chenenni1, Chenchou,
Ghannouch, Sardi, Chenenni 2, Tboulbou, Tamantit, Rich 2, Magali and Douz
which are characterized by average contents of potassium, sodium and phosphorus.
Group 2 (G2): Formed by: Ameristand 801S, Demnat 203, Kattana
and ABT 805 which are characterized by high percentages of sodium, averages
out of potassium and contents fairly weak phosphorus.
Group 3 (G3): Formed by: Limaguess, Cossouls, Zerkine, Elgolaa
Chenenni 3, Mamunts, Metwia, Hamma Jerid, Jersine, Esicilia, Bouhlel,
Essdada, Stiftimia, Nouael, Degach, Zaafarane, Prosemet, Melissa and African,
which is characterized by high percentages of sodium and potassium and
average contents phosphorus.
||Hierarchical classification by combing all parameters
At the alfalfa (Medicago sativa L.) the new studied parameters
made it possible to differentiate the various populations. The groups
highlighted are distinguished geographically. The introduced populations
form a separated group with weak performances. The local populations present
average performances at high. Variability is rather weak or null on the
level of parameters (LP, NBP, LFC, lFC and SFC). However on the level
of the parameters of reproductions (NIP and NGP) as well as parameters
of output (PST and PSF), variability remain significant and can constitute
a parameter of characterization of genetic variability.
The importance of a number of pods was stressed by other study (Laouar
and Abdelguerfi, 2000). The morphological characterization of the alfalfa
was approached by other research tasks of which those on Medicago truncatula
and Medicago laciniata on Medicago ciliaris on Medicago polymorpha
and Medicago orbicularis and out of Medicago sativa L. in the
area of Ouargla (Algeria) which shows that the variety Gabès 2355 is relatively
more productive than the other local populations. It is characterized by a fresh
weight, a dry weight, a number of ramifications, a height of the plant, a No.
of the inflorescences by plant and a No. of seeds by relatively significant
plants and a No. of seeds. Other quantitative parameters were studied at Medicago
sativa L. by Jenczewski et al. (1999),
in particular, leaf area, the length and the diameter of the stem, the number
of primary branches and the vegetative productivity. This study shows significant
differences inter populations and finds that these parameters can characterize
variability. In addition 17 criteria relating to the development vegetative
and reproductive were studied at 28 populations of Medicago polymorpha and
they are analyzed by statistical procedures (variance analysis, varied analysis
multi…), it was shown that the parameters of flowering (precocity, a number
of flowers by inflorescence) contribute more to the structuring of variability.
The composition out of sodium, potassium and out of phosphorus shows a significant
variability between the populations. In this study the sodium contents vary
from 0.061 to 0.159 %, those out of phosphorus lie between 0.06 and 0.274%,
whereas those out of potassium vary between 1.08 and 2.67%. These results agree
with those obtained by Mauriès (2003). This same researcher
showed that the alfalfa is rich in other minerals, in particular, the magnesium
whose contents vary between 0.12 to 0.22% and the calcium whose content varies
from 1.1 to 1.9%.
It proved that the alfalfa (Medicago sativa L.) is richer in potassium
than out of sodium or phosphorus. This gradient of content of minerals,
also, is obtained at Artemisia bleached on Grass alba. According
to the variability of the mineral composition at the plants can be allotted
to the nature of the ground which can change a site of taking away to
the other, to the climatic conditions which vary from one place to another
(pluviometry, altitude, temperature) and the age of the plant without
forgetting the period of the collection.
The highest content sodium characterizes the introduced population, Mamuntanas.
Whereas the lowest content (0.06%) characterizes the two populations:
Chenenni1 and Rich2. For potassium, the majority of the local populations
are characterized by high contents (between 2.16 and 2.64%), whereas the
majority of the introduced populations are characterized by average contents
with weak (between 1.08 and 2%). The phosphorus content is average for
all the populations (ranging between 0.175 and 0.2%), except for Zerkine,
Douz and African which show the rather high contents (0.24 and 0.274%).
However the two introduced populations, ABT 805 and Demnat 203 are characterized
by the lowest contents (between 0.06 and 0.07%). It was shown that the
alfalfa produced in the irrigated perimeters is richer in potassium than
that produced in the oases, whereas the phosphorus contents remain almost
identical in the two agro systems. For its part showed that the sodium
contents, out of potassium and phosphorus are variable on the level of
the 4 populations of alfalfa originating in the Tunisian south. In addition
this author showed that under the combined action of the saline stress
and the irradiation by the R have γ has provoqu a
3rd enrichment of air fabrics out of Na+ more particularly
on the level of the sheets and stems. The high Na amounts+ in
the medium of watering, generated a certain competition on the level of
the sites of absorption of K+ and thus limited the absorption
of this essential element for the growth and the development of the plant.