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Fruit and seed diversity of domesticated carob (Ceratonia siliqua L.) in Morocco
Mohamed Mahmoud Sidina
a
, Mohammed El Hansali
a
, Nadia Wahid
b
, Aziz Ouatmane
b
,
Abdelali Boulli
b
, Abdelmajid Haddioui
a,
*
a
Laboratoire de Gestion et Valorisation des Ressources Naturelles, Equipe de Ge
´ne
´tique et Biotechnologie Ve
´ge
´tale, Universite
´Sultan Moulay Slimane,
Faculte
´des Sciences et Techniques de Be
´ni Mellal, B.P 523, Be
´ni Mellal, Morocco
b
Equipe d’Environnement et Valorisation des Agro Ressources, Universite
´Sultan Moulay Slimane, Faculte
´des Sciences et Techniques de Be
´ni Mellal,
B.P 523, Be
´ni Mellal, Morocco
1. Introduction
The carob tree (Ceratonia siliqua L.) is an evergreen species with a
large distribution around the world and a controversial origin.
Zohary (1973) suggested that the Mediterranean region has been
one of its domestication centres. Carob has been cultivated for
thousands of years as a forage crop or food for human consumption
(Zohary, 2002). Recently, this species has attracted much attention
and became economically important. Pods and seedsare used as row
material in food, pharmaceutical and cosmetic industries (Batista
et al., 1996; Vourdoubas et al., 2002; Barracosa et al., 2007). It has
been introduced and grown in many dry areas of the world.
However, its cultivation and production are centered in Spain, Italy
and Portugal (Batlle and Tous, 1990). Consequently, in the northern
side of the Mediterranean basin many cultivars were characterized
(Orphanos and Papaconstantinou, 1969; Batlle and Tous, 1990;
Albanell et al., 1996; Russo and Polignano, 1996; Barracosa et al.,
2007). The characterization was focusedgenerally on morphological
traits. In Morocco, the production of carob was estimated only to 8%
of the world production. This production considered as the fourth
range in the worldis mainly fromnatural domesticated trees in agro-
forestry systems (Batlle and Tous, 1997). Indeed, the carob
distribution in Morocco is centered in the north selvage of the
Atlas chain, the Rif Mountain and in some valleys of the south-west
of the Anti-Atlas confined to arid and semi-arid bioclimates with an
extension to sub-humid bioclimate in some stands (Emberger and
Maire, 1941; Aafi, 1995). At low altitude, surrounding small
aggregate of ruralpopulations, carob trees were empiricallyselected
and propagated. In the agro-forestry systems, carob cultivation
remains still traditional and sporadicwith no grafting or silvaculture
treatment and no fertilization. Trees are only rainfed conditions.
Furthermore, based on exploitation of carob, farmers have selected
ecotypes characterized by alimentary, medicine and forage pur-
poses maintained.Local ecological conditionsare typically restricted
Scientia Horticulturae 123 (2009) 110–116
ARTICLE INFO
Article history:
Received 10 February 2009
Received in revised form 10 July 2009
Accepted 13 July 2009
Keywords:
Ceratonia siliqua
Domesticated carob
Morocco’s ecoregions
Fruit diversity
Seed diversity
ABSTRACT
The carob tree (Ceratonia siliqua L.) is an important economic resource for Morocco’s rural populations.
This species is used in reforestation actions and its cultivation in modern orchards is being undertaken to
valorize marginal lands and substitute for drought sensitive species. However, little data is available on
its intra-specific variability and its adaptability. Morphological characters of pods and seeds from 13
ecoregions of private-domesticated carob were used to assess phenotypic variation of this species. These
stands extend from south-west to north-east and cover a wide range of Morocco’s ecoregions. Pods
length, width, thickness, seeds number, pulp weight, seeds yield and seeds length, width, thickness and
weight were measured for 390 trees (30 trees per ecoregion). Statistically significant differences were
found between ecoregions for all characters which were examined, what indicates a high phenotypic
diversity. Principal component analysis (PCA) and hierarchical cluster of all ecoregions lead to identify
two major and opposite groups (the northern ecoregions; and the central and south-western
ecoregions). Ecoregions of the north of Morocco exhibited the largest and the thickest pods with the
highest pulp weight while other ecoregions have relatively short pods but largest proportion of seed
yield. Similarly, the northern ecoregions are characterized by the heaviest seeds. A correlation matrix
between morphological characters, geographic parameters and precipitation exhibits a positive and a
negative correlation of pods thickness and pulp weight with the latitude and the altitude, respectively.
Seed yield and weight are negatively and positively correlated to pod width, pod thickness and pulp
weight, respectively. In addition, seed weight is positively correlated with the latitude. The geographic
pattern of the carob tree and its variability are discussed in this paper.
ß2009 Elsevier B.V. All rights reserved.
* Corresponding author. Tel.: +212 23 48 51 12; fax: +212 23 48 52 01.
E-mail addresses: haddioui@fstbm.ac.ma,ahaddioui@yahoo.fr (A. Haddioui).
Contents lists available at ScienceDirect
Scientia Horticulturae
journal homepage: www.elsevier.com/locate/scihorti
0304-4238/$ – see front matter ß2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.scienta.2009.07.009
to a small region, generally less than 1 km
2
in size which is
particularly affected by a significant factor such as being on one side
or the other of a mountain range characterized by humid and cool
local conditions or by dry warm conditions, respectively.
The geographic situation of Morocco, surrounded by the
Mediterranean sea at the north, the Atlantic ocean at the west
and the desert at the south-west provides a wide range of
bioclimate, where carob species exhibit unusual adaptability to
warm and cold frosty bioclimates. It is associated with Argania
spinosa in warm arid bioclimates in the south-west, with Tetraclinis
articulata in warm and semi-arid bioclimate in the high Atlas, with
Quercus rotundifolia in temperate sub-humid bioclimate in the high
and the middle Atlas and with Quercus suber in cool sub-humid
bioclimate in the Rif Mountain (Gharnit et al., 2004). The ability of
this species to grow in such contrasting climatic and edaphic
conditions suggests a high degree of adaptability and a significant
variability among its members.
Recently the commercial value of carob has increased and carob
became a plant of multipurpose use (Carlson, 1986; Roukas, 1994;
Corsi et al., 2002; Makris and Kefalas, 2004; Sandolo et al., 2007). In
fact, it is used in reforestation program serving both environmental
and economic objectives in dry regions, used to valorize marginal
Fig. 1. Map of Morocco showing locations of the carob ecoregions analyzed ((*) stands, (*) ecoregions).
M.M. Sidina et al./ Scientia Horticulturae 123 (2009) 110–116
111
lands or as substitute for drought sensitive species. Its ecophy-
siological behaviour has been described as more resistant to water
stress compared to other Mediterranean species (Winer, 1980;
Nunes et al., 1992; Rejeb, 1992; Sakcali and Ozturk, 2004).
Noteworthy that if many research reports are available for this
species in several areas over the world, little or no data related with
its variability and adaptability is available in Morocco. Therefore, it
has become imperative to establish a research program aiming at
the evaluation of the genetic diversity in the Moroccan carob
germplasm.
This paper provides an investigation of pods and seeds
morphological characters variability throughout a wide distribu-
tion of domesticated carob in Morocco. Given the importance of
this species for the development of marginal areas, study would
provide interest in knowledge of its variability, adaptability and
cultivars characterization.
2. Materials and methods
2.1. Sampling and measurements
This work was carried out on different geographic regions of
domesticated carob trees in agro-forestry systems, which are
representative of the species distribution in Morocco. Based on
previous study (Boulli et al., 2001; Wahid et al., 2006) in which
climatic data were analyzed all over Morocco, a stratified sampling
method were used in which topography, vegetation homogeneity
and altitude were taken in to account. 40 sites throughout Morocco
were chosen and regrouped in 13 geographic entities named
ecoregions (Fig. 1). Each entity (ecoregion) is here defined as a
region characterized by similar topographic and climatic condi-
tions with a homogeneous flora. Geographic characteristics such as
altitude slice, central latitude and longitude as well as the mean
precipitation of these ecoregions are summarized in Table 1. The
material collection was carried out during summer 2002 as part of
a large research program including genetic diversity and ecophy-
siological studies. For each ecoregions 30 trees were randomly
chosen and sampled. 2 to 5 kg of healthy pods was sampled from
the middle part of the tree crown. 10 pods per tree and 5 seeds per
pod were examined. A total of 300 pods and 1500 seeds per
ecoregion were measured. Analysis of morphological variations
was based on the 10 character measurements related to pods and
seeds. The characters of pod that were measured are length, width,
thickness, seed number, pulp weight, and seed yield. For seed, we
have measure length, width, thickness and weight.
2.2. Statistical analysis
Analysis of morphological variations was based on the totality
of the 10 character measurement related to pods and seeds.
Variations among and within ecoregions were analyzed using
ANOVA-one way after testing for normality and homogeneity of
variance.
Correlation between morphological parameters and environ-
mental factors such as altitude, latitude, longitude and precipita-
tion was evaluated using Pearson’s correlation coefficient
(Snedecor and Cohran, 1968). Ecoregions ordination and classifi-
cation were performed using the principal component analysis
(PCA) and the hierarchical cluster analysis, respectively. The PCA
was performed on the matrix of mean values of measured
characters while the hierarchical cluster was based on Pearson’s
correlation matrix. The statistical analysis of the data was carried
out using the SPSS software windows version 9.0.
3. Results
The overall mean values for all parameters measured and their
standard deviations are presented in Table 2. High levels of
variation were found considering the 13 ecoregions studied. As
shown in Table 2, the variance analysis exhibited significant
differences between ecoregions based on all morphological
characters.
Morphological traits related with pod’s size seem to be the most
variable. In fact, pods length varied among ecoregions from
10.09 cm for Ait Berrhil to 14.36 cm for Tafraout, the mean seed
number varied from 7.97 for Ait Berrhil to 11.88 for Berkane and
the seed yield shows the highest variation, since it varied from
17.47% for Nador to 29.44% for Taza. In general, the longest, the
thickest and the largest pods and the highest pulp weight belong to
the northern ecoregions: Berkane, El Houceima, Nador and
Chefchaouen (Table 2). However, these ecoregions exhibited the
lowest seed yield. In addition, seed characteristics also varied
between ecoregions. Mean values corresponding to seeds length,
width, thickness and weight varied respectively from 0.69 cm
(Marrakech) to 0.91 cm (Nador), 0.58 cm (Essaouira) to 0.75 cm
(Issafene), 0.31 cm (Essaouira) to 0.45 cm (Berkane and Nador) and
0.15 g (Ait Berrhil, Agadir and Beni Mellal) to 0.22 g (Nador and
Chefchaouen). This result shows that the heaviest seeds belong to
the northern ecoregions (Berkane, El Houceima, Nador and
Chefchaouen).
Correlation among all morphological traits, altitude, latitude,
longitude and precipitation are summarized in Table 3. Pod length
is correlated positively with pod width, pod thickness, pulp weight,
seed number and seed weight with respective linear regression
coefficients of r= 0.723, 0.554, 0.790, 0.757 and 0.655. Further, pod
length and seed yield showed a negative correlation (r=0.500).
Seed weight is also correlated with most pod and seed characters
except with seed number and seed thickness which shows a low
correlation (r= 0.379). Seed yield exhibits a negative correlation
with all pod and seed characters and is highly significant with pod
Table 1
Geographic and meteorological conditions of ecoregions of domesticated carob (Ceratonia siliqua L.) used in the study.
Ecoregions Code Geographic region Latitude N Longitude W Altitude (m) Rainfall (mm)
Ait Berrhil P1 High Atlas (south-west) 30837
0
8820
0
200–400 250
Issafene P2 Anti-Atlas (south-west) 30808
0
8852
0
850–950 200
Tafraout P3 29842
0
8859
0
1000–1200 190
Agadir P4 West coastal 30841
0
9833
0
150–350 300
Essaouira P5 31820
0
9840
0
100–200 300
Marrakech P6 High Atlas mountain 31829
0
7843
0
700–1000 500
Beni Mellal P7 Middle Atlas mountain 32830
0
6803
0
500–800 550
Fes P8 33830
0
4856
0
1100–1300 600
Taza P9 34808
0
4808
0
500–600 700
Berkane P10 North-east 34854
0
2815
0
150–350 350
El Houceima P11 North coastal 35811
0
3857
0
50–250 327
Nador P12 35809
0
2859
0
50–250 350
Chefchaouen P13 Rif mountain 35812
0
5816
0
350–550 700
M.M. Sidina et al./ Scientia Horticulturae 123 (2009) 110–116
112
width, pulp weight, pod thickness and seed weight respectively
r=0.812, 0.770, 0.700 and 0.644.
The correlation between morphological characters and geo-
graphic characteristics shows a positive and significant correlation
between pod thickness, pulp weight and seed weight with latitude
(r= 0.711, 0.667 and 0.689, respectively), while the longitude
is negatively correlated to these morphological characters
(r=0.690, 0.608 and 0.620, respectively) and correlated also
to seed thickness (r=0.607). The seed yield is correlated
positively with altitude and precipitation (r= 0.517 and 0.528,
respectively). The pod thickness and pulp weight are correlated
with the altitude (r=0.524 and 0.506, respectively).
Principal component analysis (PCA), used as an ordination
method, was based on the 10 morphological parameters used. The
three first axes retained explain 85.31% of the total of variation,
with each component explaining respectively 57.06%, 15.7%, and
12.55%. Figs. 2 and 3 illustrated ecoregions and morphological
characters on the plot of the first three-axis space. Theses plots
exhibited the ordination of ecoregions and morphological char-
acters which are distributed along the first component. Fig. 2
shows that ecoregions may constitute two groups; the first one is
composed with the four ecoregions of north Morocco (P10, P11,
P12 and P13). The second one includes all the remaining originated
from the south-western and the central regions of Morocco. Fig. 3
shows that there is an opposition of ecoregions which are
characterized by a high seeds proportion, seed thickness and seed
number to the other with high pod width, pod length, pod
thickness and pulp weight. The second component insulates
ecoregions characterized with high seed thickness, seed width and
seed length from the others.
Hierarchical cluster analysis leads to identify two major groups
(Fig. 4) confirmingthe PCA results. The first group is composed of the
ecoregions belonging to the Rif Mountain (Chefchaouen), the north
coastal (El Houceima and Nador), the north-east (Berkane). All the
remaining ones areranged in the second cluster. Theseare spanning
the south-west of Morocco (Tafraout, Issafene and Ait Berrhil), the
west coastal (Agadir and Essaouira), the High Atlas mountain
(Marrakech) and the Middle Atlas mountain (Beni Mellal, Fes and
Taza). Noteworthy that Tafraout and Essaouira ecoregions seem to
diverge significantly from the others. In fact these could be
considered as marginal ecoregions from the south and the west.
4. Discussion
Morphological traits of pods and seeds constitute a quantitative
marker largely used together with vigour, productivity, disease
resistance, tree sex and precocity as characters differentiating
carob cultivars (Albanell et al., 1996; Yousif et al., 2000; Barracosa
et al., 2007; Naghmouchi et al., 2009). Using 12 fruit and seed
phenotypic characters, Barracosa et al. (2007) reported a high
diversity of 15 carob cultivars in Portugal. In Spanish cultivars,
Albanell et al. (1996) showed a high diversity in the morphological
parameters of pods and seeds. Morphological parameters of pods
and kernel show a high diversity in Tunisian carob population;
type and geographical origin of trees being taken as the source of
variation (Naghmouchi et al., 2009). In the world, about 50 named
cultivars are reported in the literature (Batlle and Tous, 1997)
within which about half were reported in the Mediterranean basin.
In Morocco, unpublished data by Ouchkif showed that
spontaneous populations produce less than 20% of the total
Moroccan production of carob fruit. Domesticated carob in agro-
forestry system which constitutes the major Moroccan production
has never been evaluated up the date. In spite of its economic
importance, Moroccan carobs have been neglected and no genetic
studies were reported in this local germplasm (Batlle and Tous,
1997). The present analysis of fruit and seed proved that a high
Table 2
Means, standard deviations and ‘‘F’’ values from one-way ANOVA of morphological characters determined for pods and seeds of 13 ecoregions of domesticated carob in Morocco.
Ecoregions Code Pods Seeds
Length (cm) Width (cm) Thickness (cm) Seed number Pulp weight (g) Seeds yield % Length (cm) Width (cm) Thickness (cm) Weight (g)
Ait Berrhil P1 10.09
2.03
1.56
0.37
0.52
0.15
7.97
2.72
4.03
2.08
23.04
7.56
0.79
0.08
0.61
0.07
0,42
0,08
0.15
0.05
Issafene P2 11.79
1.85
1.69
0.18
0.53
0.07
8.00
1.88
4.71
1.12
23.06
4.12
0.85
0.07
0.75
0.07
0,35
0,06
0.18
0.03
Tafraout P3 14.36
2.84
1.74
0.32
0.51
0.10
10.63
2.44
6.22
2.11
22.71
5.78
0.84
0.09
0.64
0.07
0,38
0,06
0.17
0.05
Agadir P4 12.49
2.32
1.67
0.25
0.47
0.07
9.84
2.16
4.89
1.39
23.33
6.75
0.89
0.10
0.63
0.06
0,37
0,06
0.15
0.03
Essaouira P5 13.15
2.82
1.64
0.30
0.53
0.11
9.94
2.50
6.42
3.88
21.49
7.72
0.77
0.09
0.58
0.06
0,31
0,07
0.16
0.03
Marrakech P6 13.69
2.72
1.64
0.24
0.53
0.12
11.61
2.37
5.81
2.70
26.13
8.08
0.69
0.09
0.66
0.06
0,41
0,05
0.17
0.03
Beni Mellal P7 11.99
2.33
1.54
0.22
0.53
0.10
10.81
2.49
4.89
1.73
25.06
6.55
0.83
0.08
0.63
0.06
0,41
0,05
0.15
0.03
Fes P8 11.63
2.33
1.53
0.25
0.48
0.11
9.93
2.84
4.48
2.06
25.18
7.68
0.84
0.09
0.63
0.08
0,40
0,06
0.16
0.05
Taza P9 11.25
2.06
1.50
0.19
0.51
0.09
10.19
2.45
4.05
1.19
29.44
5.60
0.84
0.09
0.63
0.08
0,40
0,06
0.16
0.05
Berkane P10 14.27
2.86
1.76
0.36
0.64
0.15
11.88
2.54
9.50
4.98
21.84
8.24
0.89
0.11
0.68
0.09
0,45
0,07
0.20
0.05
El Houceima P11 14.02
2.42
1.85
0.25
0.61
0.13
11.11
2.63
9.43
3.43
19.81
5.28
0.83
0.09
0.62
0.07
0,35
0,05
0.20
0.03
Nador P12 13.63
2.46
1.88
0.24
0.70
0.11
10.12
2.59
10.35
3.32
17.47
4.12
0.91
0.08
0.73
0.08
0,45
0,06
0.22
0.04
Chefchaouen P13 14.02
1.84
1.85
0.22
0.62
0.11
11.12
2.19
8.72
2.97
21.93
5.35
0.90
0.09
0.71
0.08
0,43
0,08
0.22
0.04
F95.59
**
20.32
**
115.50
**
70.82
**
204.28
**
62.24
**
299.98
**
652.89
**
603.11
**
452.65
**
**
Statistically significant differences between ecoregions at P<0.01.
M.M. Sidina et al./ Scientia Horticulturae 123 (2009) 110–116
113
phenotypic variation characterizes the Moroccan carobs. Seed
yield of domesticated carob is higher (17.47–29.44%) than values
concerning spontaneous one (15%) reported by Ouchkif (unpub-
lished data). These differences between domesticated and
spontaneous species strongly supported the level of selection
pressure by farmers during carob exploitation since no special
cultural practices are used. The comparison of pods-related
characters with those of the Mediterranean region described in
(Batlle and Tous, 1997) shows an overlap of pods length, width and
thickness. However, carob of northern Moroccan ecoregions
(Berkane, El Houceima, Nador and Chefchaouen) seems to be
similar to cultivars of the northern side of the Mediterranean basin
(Albanell et al., 1991; Barracosa et al., 2007). The north Moroccan
ecoregions are characterized by the longest, the largest, the
deepest pods, the largest number of seeds per pod and their pods
contain the largest pulp proportions. The other ecoregions of the
south-west and the centre are characterized by relatively short
pods and low pulp proportions. Thus, the seed yield is relatively
higher in these ecoregions than those scored in the north ones. The
similarity of carob characteristics in both sides of the Mediterra-
nean basin (north of Morocco and south Europe), suggests material
exchange between the two regions. In addition, our data is in
agreement with the (Batlle and Tous, 1997) hypothesis and
strongly supported its dissemination in the north African
countries, Spain and Portugal through out the Arabic civilizations.
The PCA plot (Fig. 2) and the hierarchical cluster (Fig. 4) show
that Moroccan domesticated carob constitutes two geographically
distinct groups based only on pod and seed morphological traits. In
the whole range of its distribution, including domesticated and
natural carob in Morocco, there is a high degree of biodiversity.
Many ecotypes are morphologically recognised by farmers, named
as El Horr, El Beldi, EL Hamiri and Dial Eddib some of which are
hybrids between domesticated and spontaneous trees. The
dominant vernacular name in the northern ecoregions is El Horre.
All over its range in Morocco, carob trees grow on a diversified
soil substrate and show an indifference to the lithological nature of
the soil. The other factors influencing species distribution in
Morocco, precipitation and temperature are the most important.
With respect to these factors, carob tree occupies hot and
temperate arid and semi-arid bioclimates. Furthermore, in these
bioclimates, precipitations constitute the most important climatic
parameter and a potential limiting factor. However, carob tree
shows an unusual behaviour with respect to precipitations
(Table 1). Based on the size of the area sampled and its diversified
Fig. 2. Principal component analysis of Moroccan ecoregions of domesticated carob
on the space formed by the first three axes performed on the basis of pods and seeds
morphological characters. Floor projection of ecoregions is used to show
contrasting situation of ecoregions on the three axes space.
Fig. 3. Principal component analysis, floor projection of morphological characters
on the space formed by the first three axes (s_propo = seed proportion,
s_number = seed number, s_ thickness = seed thickness, s_width = seed width,
s_length = seed length, s_weight = seed weight, p_teknes = pod thickness,
p_width = pod width, p_weight, = pulp weight, p_length = pod length).
Table 3
Pearson coefficient correlation between geographic parameters, precipitation and morphological characters of pods and seeds of Moroccan carob tree.
Characters 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Pod length (1) 1
Pod width (2) 0.723
**
1
Pod thickness (3) 0.554
*
0.723
**
1
Pulp weight (4) 0.790
**
0.813
**
0.919
**
1
Seed number (5) 0.757
**
0.257 0.371 0.552
*
1
Seed yield (6) 0.500
*
0.812
**
0.700
**
0.770
**
0.012 1
Seed length (7) 0.157 0.409 0.418 0.406 0.001 0.392 1
Seed width (8) 0.247 0.504
*
0.537
*
0.382 0.045 0.296 0.466 1
Seed weight (9) 0.655
*
0.844
**
0.903
**
0.895
**
0.379 0.644
*
0.486 0.676
*
1
Seed thickness (10) 0.052 0.058 0.480 0.296 0.297 0.012 0.326 0.415 0.379 1
Altitude (11) 0.136 0.353 0.524
*
0.506
*
0.070 0.517
*
0.232 0.122 0.302 0.019 1
Latitude (12) 0.311 0.311 0.711
**
0.667
*
0.514
*
0.238 0.430 0.233 0.689
**
0.455 0.383 1
Longitude (13) 0.259 0.238 0.690
**
0.608
*
0.490 0.175 0.435 0.294 0.620
*
0.607
*
0.213 0.916
**
1
Precipitation (14) 0.100 0.258 0.002 0.076 0.406 0.528
*
0.032 0.006 0.074 0.381 0.165 0.570
*
0.445 1
*
Correlation is significant at the 0.05 level.
**
Correlation is significant at the 0.01 level.
M.M. Sidina et al./ Scientia Horticulturae 123 (2009) 110–116
114
ecological conditions, environmental impact must be important.
However, introduction of carob in Morocco is ancient and the
differential effect of environment on carob is believed to be already
included in the morphological differences of present fruits due to
adaptation and anthropologic genetic selection. In addition, in the
sampled region no fertilization or silvaculture treatment was used.
There was no study on polinisation but a delay in the onset of the
growing season has been observed between the south and the
north.
These results show that Moroccan carob which is neglected by
research and development programs until now presents a high
variability. Although there is a potential effect of the climate,
these results show that there is a genetic part in this variability.
Indeed, through its range, carob grows in the most contrasting
ecological conditions, from hot and arid bioclimates such as
Tafraout and Issafen ecoregions with precipitations less than
200 mm to temperate and sub-humid bioclimates in the northern
ecoregions such as Chefchaouen with an annual precipitation rate
of 700 mm. In term of frost resistance, in El Ksiba stand (the most
known stand in the Beni Mellal’s ecoregion) carob shows unusual
behaviour supporting very low winter temperatures of 2 8C.
According to the geographic situation of Moroccan carob
constituting the marginal populations of its centre of diversity,
its ecological adaptability and its economic and environmental
importance, there is a considerable interest in knowledge of the
presence of genetic variation. Indeed, marginal populations might
contain original gene leading trees to grow in extreme environ-
ments that provide available and additional material for current
and future breeding programs.
It is obvious that survey of genetic diversity in Moroccan carob
using agronomic traits (precocity, yield, resistance to biotic and
abiotic factors), biochemical and molecular markers are projected
and would be a complement for this study.
Acknowledgements
This work was supported by grants from the Council of Tadla-
Azilal Region (Morocco) and the International Foundation for
Sciences (D 3033-1 Stockholm, Sweden).
The authors thank Pr. Omar M’HIRIT for the revision of the
manuscript.
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