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Fruit and seed diversity of domesticated carob (Ceratonia siliqua L.) in Morocco
Scientia Horticulturae 123 (2009) 110–116
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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
A R T I C L E I N F O
A B S T R A C T
Article history: Received 10 February 2009 Received in revised form 10 July 2009 Accepted 13 July 2009
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. ß 2009 Elsevier B.V. All rights reserved.
Keywords: Ceratonia siliqua Domesticated carob Morocco’s ecoregions Fruit diversity Seed diversity
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 seeds are 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
* Corresponding author. Tel.: +212 23 48 51 12; fax: +212 23 48 52 01. E-mail addresses: [email protected], [email protected] (A. Haddioui). 0304-4238/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.scienta.2009.07.009
(Orphanos and Papaconstantinou, 1969; Batlle and Tous, 1990; Albanell et al., 1996; Russo and Polignano, 1996; Barracosa et al., 2007). The characterization was focused generally 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 world is mainly from natural domesticated trees in agroforestry 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 rural populations, carob trees were empirically selected and propagated. In the agro-forestry systems, carob cultivation remains still traditional and sporadic with 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 purposes maintained. Local ecological conditions are typically restricted
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to a small region, generally less than 1 km2 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
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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).
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lands or as substitute for drought sensitive species. Its ecophysiological 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 distribution 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 conditions 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 ecophysiological 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 environmental factors such as altitude, latitude, longitude and precipitation was evaluated using Pearson’s correlation coefficient (Snedecor and Cohran, 1968). Ecoregions ordination and classification 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 Issafene Tafraout Agadir Essaouira Marrakech Beni Mellal Fes Taza Berkane El Houceima Nador Chefchaouen
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13
High Atlas (south-west) Anti-Atlas (south-west)
308370 308080 298420 308410 318200 318290 328300 338300 348080 348540 358110 358090 358120
88200 88520 88590 98330 98400 78430 68030 48560 48080 28150 38570 28590 58160
200–400 850–950 1000–1200 150–350 100–200 700–1000 500–800 1100–1300 500–600 150–350 50–250 50–250 350–550
250 200 190 300 300 500 550 600 700 350 327 350 700
West coastal High Atlas mountain Middle Atlas mountain
North-east North coastal Rif mountain
0.15 0.05 0.18 0.03 0.17 0.05 0.15 0.03 0.16 0.03 0.17 0.03 0.15 0.03 0.16 0.05 0.16 0.05 0.20 0.05 0.20 0.03 0.22 0.04 0.22 0.04 452.65** Statistically significant differences between ecoregions at P < 0.01.
7.97 2.72 8.00 1.88 10.63 2.44 9.84 2.16 9.94 2.50 11.61 2.37 10.81 2.49 9.93 2.84 10.19 2.45 11.88 2.54 11.11 2.63 10.12 2.59 11.12 2.19 70.82** 0.52 0.15 0.53 0.07 0.51 0.10 0.47 0.07 0.53 0.11 0.53 0.12 0.53 0.10 0.48 0.11 0.51 0.09 0.64 0.15 0.61 0.13 0.70 0.11 0.62 0.11 115.50** 1.56 0.37 1.69 0.18 1.74 0.32 1.67 0.25 1.64 0.30 1.64 0.24 1.54 0.22 1.53 0.25 1.50 0.19 1.76 0.36 1.85 0.25 1.88 0.24 1.85 0.22 20.32** 10.09 2.03 11.79 1.85 14.36 2.84 12.49 2.32 13.15 2.82 13.69 2.72 11.99 2.33 11.63 2.33 11.25 2.06 14.27 2.86 14.02 2.42 13.63 2.46 14.02 1.84 95.59** P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 Ait Berrhil Issafene Tafraout Agadir Essaouira Marrakech Beni Mellal Fes Taza Berkane El Houceima Nador Chefchaouen F
4. Discussion
**
Thickness (cm)
0,42 0,08 0,35 0,06 0,38 0,06 0,37 0,06 0,31 0,07 0,41 0,05 0,41 0,05 0,40 0,06 0,40 0,06 0,45 0,07 0,35 0,05 0,45 0,06 0,43 0,08 603.11** 0.61 0.07 0.75 0.07 0.64 0.07 0.63 0.06 0.58 0.06 0.66 0.06 0.63 0.06 0.63 0.08 0.63 0.08 0.68 0.09 0.62 0.07 0.73 0.08 0.71 0.08 652.89**
Width (cm) Length (cm)
0.79 0.08 0.85 0.07 0.84 0.09 0.89 0.10 0.77 0.09 0.69 0.09 0.83 0.08 0.84 0.09 0.84 0.09 0.89 0.11 0.83 0.09 0.91 0.08 0.90 0.09 299.98** 23.04 7.56 23.06 4.12 22.71 5.78 23.33 6.75 21.49 7.72 26.13 8.08 25.06 6.55 25.18 7.68 29.44 5.60 21.84 8.24 19.81 5.28 17.47 4.12 21.93 5.35 62.24**
Seeds
Seeds yield % Pulp weight (g) Seed number Thickness (cm) Width (cm) Pods
Length (cm)
Code Ecoregions
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.
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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 geographic 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 characters 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) confirming the 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 are ranged in the second cluster. These are 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.
4.03 2.08 4.71 1.12 6.22 2.11 4.89 1.39 6.42 3.88 5.81 2.70 4.89 1.73 4.48 2.06 4.05 1.19 9.50 4.98 9.43 3.43 10.35 3.32 8.72 2.97 204.28**
Weight (g)
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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 agroforestry 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
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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) Pod width (2) Pod thickness (3) Pulp weight (4) Seed number (5) Seed yield (6) Seed length (7) Seed width (8) Seed weight (9) Seed thickness (10) Altitude (11) Latitude (12) Longitude (13) Precipitation (14)
1 0.723** 0.554* 0.790** 0.757** 0.500* 0.157 0.247 0.655* 0.052 0.136 0.311 0.259 0.100
1 0.723** 0.813** 0.257 0.812** 0.409 0.504* 0.844** 0.058 0.353 0.311 0.238 0.258
1 0.919** 0.371 0.700** 0.418 0.537* 0.903** 0.480 0.524* 0.711** 0.690** 0.002
1 0.552* 0.770** 0.406 0.382 0.895** 0.296 0.506* 0.667* 0.608* 0.076
1 0.012 0.001 0.045 0.379 0.297 0.070 0.514* 0.490 0.406
1 0.392 0.296 0.644* 0.012 0.517* 0.238 0.175 0.528*
1 0.466 0.486 0.326 0.232 0.430 0.435 0.032
1 0.676* 0.415 0.122 0.233 0.294 0.006
1 0.379 0.302 0.689** 0.620* 0.074
1 0.019 0.455 0.607* 0.381
1 0.383 0.213 0.165
1 0.916** 0.570*
1 0.445
1
* **
Correlation is significant at the 0.05 level. Correlation is significant at the 0.01 level.
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 (unpublished 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 Mediterranean 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
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.
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. 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).
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Fig. 4. Dendrogram (hierarchical clustering) of 13 ecoregions of Moroccan carob based on morphological traits.
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 environments 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
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Russo, G., Polignano, G.B., 1996. Variation of seed and fruit characters in Ceratonia siliqua L. cultivars. Genet. Resour. Crop Evol. 43, 525–553. Sandolo, C., Coviello, T., Matricardi, P., Alhaique, F., 2007. Characterization of polysaccharide hydrogels for modified drug delivery. Eur. Biophys. J. 36 (7), 693–700. Sakcali, M.S., Ozturk, M., 2004. Eco-physiological behaviour of some Mediterranean plants as suitable candidates for reclamation of degraded areas. J. Arid Environ. 57, 1–13. Snedecor, G., Cohran, W., 1968. Statistical Methods. The Iowa State Univ. Press, Ames, IA, USA, 593 pp. Vourdoubas, J., Makris, P., Kefalas, J., Kaliakatsos, J., 2002. Studies on the production of bioethanol from carob. In: The 12th National Conference and Technology Exhibition on Biomass for Energy. Industry and Climate Protection, Proceedings, Amsterdam, pp. 489–493. Wahid, W., Gonza´lez-Martı´nez, S.C., El Hadrami, I., Boulli, A., 2006. Variation of morphological traits in natural populations of maritime pine (Pinus pinaster Ait) in Morocco. Ann. For. Sci. 63, 83–92. Winer, N., 1980. The potential of the carob (Ceratonia siliqua L.). Int. Tree Crops J. 1, 15–26. Yousif, Ali, k., Alghzawi, H.M., 2000. Processing and characterization of carob powder. Food Chem. 69, 283–287. Zohary, M., 1973. Geobotanical Foundations of the Middle East 2 Vols. Stuttgart. Zohary, M., 2002. Domestication of the carob (Ceratonia siliqua L.). Israel J. Plant Sci. 50, 141–145.
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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
A R T I C L E I N F O
A B S T R A C T
Article history: Received 10 February 2009 Received in revised form 10 July 2009 Accepted 13 July 2009
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. ß 2009 Elsevier B.V. All rights reserved.
Keywords: Ceratonia siliqua Domesticated carob Morocco’s ecoregions Fruit diversity Seed diversity
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 seeds are 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
* Corresponding author. Tel.: +212 23 48 51 12; fax: +212 23 48 52 01. E-mail addresses: [email protected], [email protected] (A. Haddioui). 0304-4238/$ – see front matter ß 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.scienta.2009.07.009
(Orphanos and Papaconstantinou, 1969; Batlle and Tous, 1990; Albanell et al., 1996; Russo and Polignano, 1996; Barracosa et al., 2007). The characterization was focused generally 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 world is mainly from natural domesticated trees in agroforestry 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 rural populations, carob trees were empirically selected and propagated. In the agro-forestry systems, carob cultivation remains still traditional and sporadic with 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 purposes maintained. Local ecological conditions are typically restricted
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to a small region, generally less than 1 km2 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
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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
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lands or as substitute for drought sensitive species. Its ecophysiological 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 distribution 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 conditions 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 ecophysiological 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 environmental factors such as altitude, latitude, longitude and precipitation was evaluated using Pearson’s correlation coefficient (Snedecor and Cohran, 1968). Ecoregions ordination and classification 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 Issafene Tafraout Agadir Essaouira Marrakech Beni Mellal Fes Taza Berkane El Houceima Nador Chefchaouen
P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13
High Atlas (south-west) Anti-Atlas (south-west)
308370 308080 298420 308410 318200 318290 328300 338300 348080 348540 358110 358090 358120
88200 88520 88590 98330 98400 78430 68030 48560 48080 28150 38570 28590 58160
200–400 850–950 1000–1200 150–350 100–200 700–1000 500–800 1100–1300 500–600 150–350 50–250 50–250 350–550
250 200 190 300 300 500 550 600 700 350 327 350 700
West coastal High Atlas mountain Middle Atlas mountain
North-east North coastal Rif mountain
0.15 0.05 0.18 0.03 0.17 0.05 0.15 0.03 0.16 0.03 0.17 0.03 0.15 0.03 0.16 0.05 0.16 0.05 0.20 0.05 0.20 0.03 0.22 0.04 0.22 0.04 452.65** Statistically significant differences between ecoregions at P < 0.01.
7.97 2.72 8.00 1.88 10.63 2.44 9.84 2.16 9.94 2.50 11.61 2.37 10.81 2.49 9.93 2.84 10.19 2.45 11.88 2.54 11.11 2.63 10.12 2.59 11.12 2.19 70.82** 0.52 0.15 0.53 0.07 0.51 0.10 0.47 0.07 0.53 0.11 0.53 0.12 0.53 0.10 0.48 0.11 0.51 0.09 0.64 0.15 0.61 0.13 0.70 0.11 0.62 0.11 115.50** 1.56 0.37 1.69 0.18 1.74 0.32 1.67 0.25 1.64 0.30 1.64 0.24 1.54 0.22 1.53 0.25 1.50 0.19 1.76 0.36 1.85 0.25 1.88 0.24 1.85 0.22 20.32** 10.09 2.03 11.79 1.85 14.36 2.84 12.49 2.32 13.15 2.82 13.69 2.72 11.99 2.33 11.63 2.33 11.25 2.06 14.27 2.86 14.02 2.42 13.63 2.46 14.02 1.84 95.59** P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 Ait Berrhil Issafene Tafraout Agadir Essaouira Marrakech Beni Mellal Fes Taza Berkane El Houceima Nador Chefchaouen F
4. Discussion
**
Thickness (cm)
0,42 0,08 0,35 0,06 0,38 0,06 0,37 0,06 0,31 0,07 0,41 0,05 0,41 0,05 0,40 0,06 0,40 0,06 0,45 0,07 0,35 0,05 0,45 0,06 0,43 0,08 603.11** 0.61 0.07 0.75 0.07 0.64 0.07 0.63 0.06 0.58 0.06 0.66 0.06 0.63 0.06 0.63 0.08 0.63 0.08 0.68 0.09 0.62 0.07 0.73 0.08 0.71 0.08 652.89**
Width (cm) Length (cm)
0.79 0.08 0.85 0.07 0.84 0.09 0.89 0.10 0.77 0.09 0.69 0.09 0.83 0.08 0.84 0.09 0.84 0.09 0.89 0.11 0.83 0.09 0.91 0.08 0.90 0.09 299.98** 23.04 7.56 23.06 4.12 22.71 5.78 23.33 6.75 21.49 7.72 26.13 8.08 25.06 6.55 25.18 7.68 29.44 5.60 21.84 8.24 19.81 5.28 17.47 4.12 21.93 5.35 62.24**
Seeds
Seeds yield % Pulp weight (g) Seed number Thickness (cm) Width (cm) Pods
Length (cm)
Code Ecoregions
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.
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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 geographic 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 characters 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) confirming the 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 are ranged in the second cluster. These are 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.
4.03 2.08 4.71 1.12 6.22 2.11 4.89 1.39 6.42 3.88 5.81 2.70 4.89 1.73 4.48 2.06 4.05 1.19 9.50 4.98 9.43 3.43 10.35 3.32 8.72 2.97 204.28**
Weight (g)
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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 agroforestry 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
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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) Pod width (2) Pod thickness (3) Pulp weight (4) Seed number (5) Seed yield (6) Seed length (7) Seed width (8) Seed weight (9) Seed thickness (10) Altitude (11) Latitude (12) Longitude (13) Precipitation (14)
1 0.723** 0.554* 0.790** 0.757** 0.500* 0.157 0.247 0.655* 0.052 0.136 0.311 0.259 0.100
1 0.723** 0.813** 0.257 0.812** 0.409 0.504* 0.844** 0.058 0.353 0.311 0.238 0.258
1 0.919** 0.371 0.700** 0.418 0.537* 0.903** 0.480 0.524* 0.711** 0.690** 0.002
1 0.552* 0.770** 0.406 0.382 0.895** 0.296 0.506* 0.667* 0.608* 0.076
1 0.012 0.001 0.045 0.379 0.297 0.070 0.514* 0.490 0.406
1 0.392 0.296 0.644* 0.012 0.517* 0.238 0.175 0.528*
1 0.466 0.486 0.326 0.232 0.430 0.435 0.032
1 0.676* 0.415 0.122 0.233 0.294 0.006
1 0.379 0.302 0.689** 0.620* 0.074
1 0.019 0.455 0.607* 0.381
1 0.383 0.213 0.165
1 0.916** 0.570*
1 0.445
1
* **
Correlation is significant at the 0.05 level. Correlation is significant at the 0.01 level.
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 (unpublished 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 Mediterranean 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
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.
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. 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).
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Fig. 4. Dendrogram (hierarchical clustering) of 13 ecoregions of Moroccan carob based on morphological traits.
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 environments 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
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