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Morocco is one of the major exporters of small citrus fruits, such as mandarin and Clementine. Seedlessness is a major criterion for this horticultural group. The present study focused on the selection of the best triploid mandarin hybrids characterized by seedless fruits. A series of crosses between ‘Sidi Aissa’ clementine (female parent) and seven mandarin varieties was performed by the National Institute for Agricultural Research. Forty triploid mandarins were obtained and planted in an experimental field at El Menzeh. Varietal evaluation focusedon fruit quality traits during seven years. Statistical analyzes have shown that there are significant differences between the hybrids and for all the traits studied. The number of seeds per fruit is the main criterion that differentiates the triploid tangerine hybrids from the diploid clementine mother plant Sidi Aissa. Thus, the best hybrids selected are : HT11, HT13, HT27, HT43, HT44, and HT49. Among these promising hybrids, two have been listed in the official catalog under the names of HANA (HT11) and AYA (HT44). Likewise, the best crosses are C1 (SidiAissaXWilking) and C2 (SidiAissaXOsceola)., African and Mediterranean Agricultural Journal - Al Awamia, No 129 (2020): Advances in Citrus Research - Special Issue

The objective of the present paper was to evaluate the effect of nitrogen level on yield and fruit quality of citrus and to determine the optimum N fertilizer rates of Navel orange variety budded on Troyer citrange rootstock in field conditions. The orange Navel orchard spaced 7mx7m (204 trees/ha) grown in 1964 on a sandy soil at the experimental station of El Menzeh, INRA Morocco. The experiment was set up in a complete randomized block design with three blocks and the experimental unit was composed on 4 consecutive trees in the row. Four fertilization treatments of N (Kg/ha) (T0 (control): 0, T1: 100, T2: 200, T3: 300) were applied to Navel citrus tree in field conditions over two seasons 2012-2013 and 2013-2014.Fruit yield, fruit weight, fruit size, total soluble sugar (TSS) content, acidity of juice and maturity index of Navel orange were significantly affected by increasing N level. Fruit yield/tree was improved significantly with increase in N rate. Significant highest yields (129.21 and 139.82. kg/tree) were recorded under treatments T2 and T3 respectively. The lowest fruit yield/tree was obtained from untreated control plot. Maximum fruit weight (268.54 and 276.50 g) and fruit size (78.94 and 80.87 mm) was recorded with the same treatments T2 and T3 respectively. Total soluble sugar content was also maximum in trees receiving treatment (T2) and treatment (T3) 12.20 and 11.70°Brix respectively. Significant increase in acidity of juice of fruit Navel orange was also recorded by increasing the rate of N. The highest acidity (1.13 and 1.20%) was achieved by the same treatments T2 and T3 respectively. Two-year studies showed that application of fertilizers at the rate of 200 Kg N/ha would be optimum for achieving higher yield and better fruit quality of Navel orange variety in sandy soil in Gharb area., African and Mediterranean Agricultural Journal - Al Awamia, No 129 (2020): Advances in Citrus Research - Special Issue

Among the Citrus genus, mandarins are characterized by a large diversity of species, but only a few varieties are marketed. The objective of this study is to characterize and evaluate 70 varieties of mandarins from the Citrus germplasm at INRA Kenitra according to morphological and physico-chemical criteria over four consecutive years. Highly significant differences were revealed for all the traits studied. Like Wase, the maturity coefficient made it possible to classify the varieties in three groups (Late, early and half season). These groups offer a large possibility of choice of parents for the creation of seedless mandarins with high yield potential. In addition, the cluster analysis based on qualitative and quantitative data classified all varieties into three large groups, each of which contains phenotypic close varieties. The mandarin germplasm could underlie a varietal creation program and a new strategy of preservation ex situ, African and Mediterranean Agricultural Journal - Al Awamia, No 129 (2020): Advances in Citrus Research - Special Issue

We examined the combined influence of irrigation regime and rootstock on Phytophthora spp. population density in citrus rhizosphere under field conditions. We carried out the study in a young orchard of Clementine, variety Sidi Aissa, grafted onto five rootstocks:, i.e. carrizo citrange, citrange C35, Citrus macrophylla, sour orange and the hybrid Cleopatra mandarin x citrange Carrizo 30577. Three water regimes were applied: Control (T0) irrigated at 100% of ETc, and deficit irrigation (T1) and (T2) at 75% and 50% of ETc, respectively. Results show that Phytophthora spp. Inoculum density varied significantly between the different irrigation regimes and rootstock genotypes. Phytophthora spp. density was significantly lower under the more severe deficit irrigation T2 than under T0 or T1. Also, a significant and positive correlation was found between soil moisture and inoculum density of Phytophthora spp. in the rhizosphere of C. macrophylla and Carrizo citrange rootstocks. Among rootstocks, the highest population densities of Phytophthora spp. were demonstrated for C. macrophylla and sour orange rhizosphere under 100% ETc regime, while no inoculum was evidenced from the root zone of C. macrophylla under 50% ETc. Results showed that Carrizo citrange and C. macrophylla were more sensitive to soil moisture indicating that watering regime is a key factor to minimize Phytophthora spp. density in the rhizosphere of these rootstocks. Results also revealed that Carrizo citrange and C. macrophylla rootstocks can be recommended under deficit irrigation in order to reduce Phytophthora spp. infection in citrus orchards., African and Mediterranean Agricultural Journal - Al Awamia, No 129 (2020): Advances in Citrus Research - Special Issue

Mineral nutrition is one of the most important components of citrus production management. The volume of production and fruit quality are closely related to mineral nutrition given to citrus trees. The objective of the present study was to evaluate the effect of different nitrogen, phosphorus and potassium levels on yield, fruit size, fruit weight and fruit quality (juice content, sugar content, acidity and maturity index) of the clementine (Citrus reticulata Blanco) var. Sidi Aissa grafted onto sour orange (Citrus aurantium L.). The study was conducted in field condition in Tadla region, Morocco. Treatments consisted of four different levels of nitrogen (N: 0, 30, 110, 250 kg/ha), phosphorus (P2O5: 0, 10, 45, 100 kg/ha) and potassium (K2O: 0, 30, 110, 240 kg/ha) in an incomplete factorial randomized block design. The results of this study showed that the different levels of nitrogen, phosphorus and potassium had significant effects on all the parameters studied. The highest values for yield, fruit size, fruit weight and fruit quality (juice content, total soluble sugar, acidity and maturity index) were obtained with 110 kg/ha, 10 kg /ha and 110 kg/ha of N, P2O5 and K2O respectively. The results of this study provide new knowledge to optimize the yield and fruit quality of clementine Sidi Aissa with better nutrient management in the field conditions of Tadla region., African and Mediterranean Agricultural Journal - Al Awamia, No 129 (2020): Advances in Citrus Research - Special Issue

Ahmed Fadili, Abdelali Halimi, Hicham Benyahia, Fatima Zaoui Department of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Medicine, Mohammed V University, Rabat, Morocco Purpose: The purpose of the present study was to evaluate a semiautomated segmentation tool designated for the volume measurements of teeth root; this method is based on three-dimensional and focused to follow-up the root’s volume when an orthodontic treatment occurred. Materials and methods: In order to evaluate a semiautomated segmentation tool, a cone beam computed tomography (CBCT) was selected with 20 intact teeth (10 maxillary and 10 mandibular teeth), CBCT images were imported into the ImageJ software, and the root volumes were measured using two methods (the semiautomated segmentation and the manual segmentation). Both segmentations are carried out by two experts; the manual segmentation served as a reference method and considered as the “gold standard”. The data were analyzed using the Bland–Altman analysis to compare the agreement between methods, and the intraclass correlation coefficient (ICC) was used to assess the interobserver reliability. Results: The Bland–Altman analysis revealed the agreement between measurements on semiautomated segmentation and manual segmentation, with a mean bias of –2.09mm3 and the 95% limits of agreement of –11.38 to 7.21mm3. The ICC was 0.999 for semiautomated segmentation method and 0.999 for manual segmentation method. Conclusion: The use of stereology employing the ImageJ software and CBCT images provide an accurate and reliable semiautomated segmentation, leading to an approach of volume quantitative analysis to evaluate and follow-up the root’s volume when orthodontic treatment occurred. Further clinical studies are necessary to explore this method. Keywords: three-dimensional imaging, segmentation, accuracy, orthodontic treatment, ImageJ software, root resorption

Introduction : La salinité des sols et des eaux d’irrigation constituent une contrainte abiotique dont les conséquences impactent autant la production que la qualité des agrumes. L’utilisation d’un porte-greffe résistant à ces conditions apparaît la solution la plus adaptée.Objectifs : Cette étude est la comparaison de comportement de génotypes d’agrumes, en termes de résistance à la salinité in vitro au niveau des cals et des cellules cultivées parallèlement sur milieu liquide et solide.Méthodologie et résultat : À cet égard, des cals de quatre génotypes d’agrumes : mandarinier Cléopâtre (citrus reshni hort ex Tan), mandarinier commun (citrus delicosa Ten.), pomelo Star Ruby ruby (citrus paradisi Macfad.cv Star Ruby) et orange Shamouti (citrus sinensis) ont été maintenus sur des milieux MT renfermant des doses de NaCl 0, 50, 100, 150 et 200 mM. Les résultats ont montré que les différents niveaux de stress de salinité ont eu un effet significatif sur la croissance des cellules. En outre, la salinité a augmenté de façon significative le niveau de chlorures des génotypes testés.Conclusions et application des résultats : Un comportement différentiel sur les niveaux de tolérance à la salinité a été révélé, entre génotypes d’une part, et entre types de milieu d’autre part. Le mandarinier Cléopâtre et le pomelo Star Ruby ont montré la meilleure réponse sous stress salin. La culture des suspensions cellulaires peut être un outil efficace pour étudier le comportement des génotypes d'agrumes vis-à-vis la salinité.Mots clefs : Agrumes, salinité, tolérance, cals, suspension cellulaire Introduction: Soil and water salinity is an important abiotic stress that can affect both production and quality of citrus fruits. The use of tolerant rootstocks under these conditions would be a promising solution.Objectives: The aim of this study was to compare in vitro behaviour of four citrus genotypes in terms of salt tolerance using callus and cells grown in parallel on liquid and solid media.Methodology and Results: In this regard, calluses of four genotypes of citrus: Cleopatra mandarin (Citrus reshni hort ex Tan), Willow leaf mandarin (Citrus delicosa Ten.), ‘Star Ruby’ grapefruit (Citrus paradisi Ruby), and ‘Shamouti’ sweet orange (Citrus sinensis) were maintained on MT media containing different NaCl doses, i.e.: 0, 50, 100, 150, and 200 mM. The results showed that the different salt levels used had a significant effect on cell growth, resulting in a decrease in fresh and dry weights. In addition, salinity increased considerably Chloride concentrations in the tested genotypes.Conclusions and application of findings: A differential behaviour of salt tolerance was found between citrus calluses used depending on genotype on one hand, and type of medium on other hand. Compared to the other genotypes, Cleopatra mandarin and Star Ruby grapefruit showed the best performance under salt stress conditions. These results suggest that culture cell suspensions can be an effective tool for studying the behaviour of citrus species under salinity.Keywords: Citrus, salinity, tolerance, callus, cell suspension

Introduction: Au Maroc, les agrumes sont plantés dans différentes régions à conditions de sol et climats variées. Dans la majorité de ces régions notamment le Souss, le Tadla et le Haouz, les agrumes se trouvent souvent dans des situations de manque d’eau saisonnier. Le recours à l’irrigation est dès lors inévitable pour assurer la production. L’étude du comportement de l’association variété x porte-greffes vis-à-vis le déficit hydrique se situe parmi les voies les plus adaptées pour sélectionner les combinaisons performantes en termes d’utilisation en eau et d’adaptation aux conditions de sécheresse.Objectif: Notre travail vise à étudier la réponse à un déficit hydrique des plants de clémentine Citrus reticulata Swingle var. Sidi Aissa greffé sur cinq porte-greffes d’agrumes différents par le suivi de quelques paramètres physiologiques et morphologiques. Les paramètres évalués ont été la croissance sur quatre mois, la conductance stomatique, la teneur en chlorophylle (SPAD) et la teneur en sucres solubles dans les feuilles dans un but de sélectionner les porte-greffes présentant un potentiel de résistance au stress hydrique. Les porte-greffes testés ont été le Citrus volkameriana, Citrus macrophylla, Citrange C35 (Citrus sinensis (L.) Osb. x Poncirus trifoliata (L.) Raf.), Citrange Carrizo (Citrus sinensis (L.) Osb. x Poncirus trifoliata (L.) Raf.) et l’hybride Mandarin Cléopâtre (Citrus reticulata var. Austera Swingle) x Citrange Carrizo 30577 (Citrus sinensis (L.) Osb. x Poncirus trifoliata (L.) Raf.).Matériel et méthodes Pour chaque porte-greffe, des plants âgés d’un an ont été cultivés en pots de plastique (10 L) dans une serre à El Menzeh, INRA Maroc. Ils ont été soumis à deux régimes hydriques de 100 % et 50 % de la capacité au champ (Hcc) du substrat. L’expérimentation a été disposée en un split-plot à deux traitements. Les paramètres morphologiques mesurés ont été la hauteur de la plante, le diamètre au point de greffage de la tige principal de porte-greffe et celui de la variété. Les paramètres physiologiques étudiés ont été la conductance stomatique, la teneur en chlorophylle (SPAD) et la teneur en sucres solubles dans les feuilles.Résultats: Les paramètres morphologiques et physiologiques ont tous été affectés par le stress hydrique appliqué, mais différemment selon le porte-greffe considéré. Le stress hydrique a induit une augmentation de la teneur en sucres solubles au niveau des feuilles. Le manque d’eau affecte d’une manière significative les caractéristiques physiologiques et morphologiques des plants de la clémentine Sidi Aissa.Conclusion et application: En conditions de déficit hydrique extrême (50 % d’Hcc), un comportement différentiel des porte-greffes a été constaté. Sur la base des résultats que nous avons obtenus, les porte-greffes Citrange Carrizo (Citrus sinensis (L.) Osb. x Poncirus trifoliata (L.) Raf.) et Citrus macrophylla procurent à la clémentine Sidi Aissa les meilleures aptitudes à résister aux conditions de stress hydrique par l’augmentation de la teneur en sucre solubles au niveau des feuilles et par le maintien de la conductance stomatique à des valeurs élevées en conditions de déficit hydrique sévères.Mots clés : sécheresse, écophysiologie, physiologie du stress, porte-greffe, citrus.

Alkalinity of Moroccan soils is the major abiotic constraint on citrus production area. The best choice of citrus rootstocks adequate and resistant is a better solution to avoid this problem. The aim of this study is to develop a fast test of citrus rootstocks screening towards alkalinity. The alkaline stress was applied on ten citrus rootstocks two month old, using irrigation with a Hoagland and Arnon solution added with 1 g CaCO(3)/L and adjusted at various pH levels 6, 7 and 9. Observations concerned symptoms incidence and severity of iron chlorosis after two months of rearing. Results permitted to classify Poncirus trifoliata and Flying dragon as the most sensitive to alkalinity stresses, whereas, Citrus volkameriana and Citrus macrophylla were resistant. These conclusions are equivalent with those obtained with old citrus rootstocks in field trials.