Lemon Citrus Research Articles

Interactions between the citrus bud mite Aceria sheldoni (Acari: Eriophyidae) and the lemon host tree in a Mediterranean area

This study evaluated the relation between the citrus bud mite [Aceria sheldoni (Ewing)] and lemon trees [(Citrus limon (L.) Burm] in two groves, over two seasons in Reggio Calabria (Italy). Random samples of shoots were taken every 10 days and the number of buds, blossoms, fruits, and leaves present on each shoot were counted. Blossoms and fruits were classified as healthy or deformed and the immature and adults stages of the citrus bud mite and associated predatory mites were counted. Observational data indicated that the citrus bud mite does not have a negative influence on the lemon harvest and that the interaction between its populations and the host plant is a mutual symbiosis in which mite populations use the buds as a resource and repay the host plant by positively regulating its productive system. In both lemon groves, three stigmaeid mites [Zetzellia mali (Ewing), Z. graeciana Gonzalez and Agistemus collyerae Gonzalez] were also collected and their density was compared with that of the A. sheldoni. Our study highlights the complexity of relations of the citrus bud mite and lemon trees, and stresses the importance of carefully determining the real influence of the citrus bud mite on host plant harvests.

Antifungal activity of lemon, eucalyptus, thyme, oregano, sage and lavender essential oils against Aspergillus niger and Aspergillus tubingensis isolated from grapes

Today, it is very important to find out the protection of products of natural origin as an alternative to synthetic fungicides. The promising alternative is the use of the essential oils (EOs). Essential oils from plants have great potential as a new source of fungicide to control the pathogenic fungi.The main objective of this study was evaluation of the antifungal activity of lemon (Citrus lemon L.), eucalyptus (Eucalyptus globulus LABILL.), thyme (Thymus vulgaris L.), oregano (Origanum vulgare L.) sage (Salvia officinalis L.) and lavender (Lavandula angustifolia MILLER.) EOs against Aspergillus niger and Aspergillus tubingensis isolated from grapes and their ability to affect the growth. It was tested by using the vapor contact with them. At first both tested isolates were identified by using PCR method. Sequence data of 18S rRNA supported the assignment of these isolates to the genus Aspergillus and species A. niger (ITS region: KT824061; RPB2: KT824060) and A. tubingensis (ITS region: KT824062; RPB2: KT824059). Second, EO antifungal activity was evaluated. The effect of the EO volatile phase was confirmed to inhibit growth of A. niger and A tubingensis. EOs were diluted in DMSO (dimethyl sulfoxide) final volume of 100 μL. Only 50 μL this solution was distributed on a round sterile filter paper (1 x 1 cm) by micropipette, and the paper was placed in the center of the lid of Petri dishes. Dishes were kept in an inverted position. The essential oils with the most significant activity were determined by method of graded concentration of oils - minimum inhibitory doses (MIDs). The most effective tested EOs were oregano and thyme oils, which totally inhibited growth of tested isolates for all days of incubation at 0.625 μL.cm-3 (in air) with MFDs 0.125 μL.cm-3 (in air). Lavender EO was less active aginst tested strains (MIDs 0.313 μL.cm-3). The results showed that the tested EOs had antifungal activity, except lemon and eucalyptus. Sage EO was the only one which decelerated the radial growth of colony of both tested strains after all days of cultivation in comparison with a control sets. Our study provides the support that essential oils can be used to control plant pathogens such as A. niger and A. tubingensis.

Assessing citrus (lemon) based intercropping in the irrigated areas of northern plains of Haryana

On-farm experiment was conducted in the village Badarpursaid of Faridabad district in Haryana to assess the various intercrop combination in the lemon orchard during 2011 to 2014. The lemon variety Baramasi (Citrus limon) was planted in the area of 2,000 sq. m. in the year 2011. During rabi 2011 to rabi 2013–14, different crops like winter vegetables (cabbage and cauliflower), summer crops as muskmelon and fodder maize and kharif crops of maize (cob and fodder) and fodder sorghum were grown as intercrop in the orchard. The comparison was made in terms of net return from the system, crop productivity index and land equivalent ratio. Results showed that the best intercropping system was lemon + fodder maize – muskmelon - cauliflower. There was enhancement in land utilization, cropping intensity and farmers’ income.

The Role of Image Enhancement in Citrus Canker Disease Detection

Digital image processing is employed in numerous areas of biology to identify and analyse problems. This approach aims to use image processing techniques for citrus canker disease detection through leaf inspection. Citrus canker is a severe bacterium-based citrus plant disease. The symptoms of citrus canker disease typically occur in the leaves, branches, fruits and thorns. The leaf images show the health status of the plant and facilitate the observation and detection of the disease level at an early stage. The leaf image analysis is an essential step for the detection of numerous plant diseases. The proposed approach consists of two stages to improve the clarity and quality of leaf images. The primary stage uses Recursively Separated Weighted Histogram Equalization (RSWHE), which improves the contrast level. The second stage removes the unwanted noise using a Median filter. This proposed approach uses these methods to improve the clarity of the images and implements these methods in lemon citrus canker disease detection.

In Vitro Inhibition Capacity in Ca Oxalate Formation by Lemon (Citrus Lemon) Juice

This research aims to determine the inhibition capacity of lemon juice (Citrus lemon) in the formation of calcium oxalate in a variety of concentrations of 5%, 7.5%, 10% which is then compared to pure citric acid. Lemon juice contains citric acid that can inhibit calcium oxalate’s formation. Inhibitory activity found in lemon juice is examined by observing its inhibition capacity towards the formation of calcium oxalate crystal. At the end of the treatment process the turbidity level is compared to citric acid acting as an inhibitor in the formation of calcium oxalate and then the percentage of the inhibition capacity is calculated. Result of the study shows that the optimum concentration of the lemon juice (Citrus lemon) and citric acid is 10%. The inhibition capacities in calcium oxalate formation by lemon juice with concentration variations of 5%, 7.5%, 10% are 47.06%, 73.68%, 94.19% and by citric acid with concentration variations of 5%, 7.5 %, 10% are 29.90%, 30.85%, 42.30%. It can be concluded that the higher the concentration of lemon juice and citric acid used the higher the inhibition capacity of calcium oxalate. Based on the inhibition capacity percentage, lemon juice is more effective in inhibiting the formation of calcium oxalate compared to citric acid and it can function as an alternative to prevent the formation of kidney stone. © 2015 JNSMR UIN Walisongo. All rights reserved

Avaliação histomorfométrica e da proliferação celular em úlceras de córnea superficiais, induzidas em coelhos, após o uso de colírio de Citrus lemon

O objetivo do presente estudo foi avaliar e comparar, por meio de histomorfometria e imuno-histoquímica para PCNA (Antígeno Nuclear de Proliferação Celular), o processo de reparação corneal de úlceras superficiais induzidas em coelhos e tratadas com colírios de óleo essencial de Citrus lemon (CL). Foram utilizadas 40 fêmeas da espécie leporina, constituindo-se quatro grupos experimentais de 10 animais cada. Todos os animais foram submetidos à indução da úlcera superficial experimental por meio da aplicação tópica de n-heptanol. Em dois grupos foram instilados colírios à base de óleo essencial de Citrus lemon, em diferentes concentrações, sendo 3% (GL3) e 5% (GL5). Outro grupo foi tratado com Tween 80 8% (GT), que é o diluente utilizado na produção dos colírios de CL; o grupo controle (GC) recebeu apenas substituto da lágrima. Todos os colírios foram aplicados quatro vezes ao dia. Os grupos experimentais foram distribuídos em dois subgrupos, com cinco animais cada, de acordo com os períodos finais de avaliação. O primeiro subgrupo (M1) foi avaliado após 24 horas e o segundo (M2), após cinco dias. Nas comparações entre os momentos iniciais e finais, os grupos tratados com substituto da lágrima, Tween 80 8% e colírio à base de óleo essencial deCitrus lemon 5% promoveram aumento na espessura epitelial na periferia da córnea e maior percentual de proliferação celular. Não houve diferença de celularidade entre os tratamentos. Os colírios à base de óleo essencial de Citrus lemon, nas diferentes concentrações, promoveram a reepitelização corneal, sem causar lesões adicionais ao epitélio ou estroma corneal, podendo ser utilizado na superfície ocular.

Utilization of home remedies to relieve Nausea and Vomiting among Pregnant Women

Background: Nausea and vomiting affect a large proportion of women in early pregnancy, yet because it is a physiological symptom it is often missed by health professionals, leaving women to find their own coping mechanisms. Many pregnant women try a range of complementary and alternative therapies and natural remedies. Aim: aim of the study was to assess home remedy utilized to relieve nausea and vomiting among pregnant women. Subjects and Methods: A descriptive cross sectional study design was adopted in this study among two hundred pregnant women attending antenatal clinics for follow- up in the 6 Maternal and Child Health Centers (MCH) in Port-Said City. A specially designed questionnaire was used to collect the data in the period between January and May 2014. Results: More than fifty of the users reported utilizing home remedies during pregnancy. The most commonly used remedies were Peppermint, lemon (citrus), vegetables, and Zangabel( Ginger). Conclusion: A large percentage of the women in the study used home remedies during pregnancy. Many of them believed that home remedies are safer on the health of their fetus than medical treatment during pregnancy. Recommendations: To develop a health education program directed toward pregnant women to increase their awareness about the benefits and harms of home remedies in ante-natal care clinics especially for herbs commonly used and the importance of consultation of health care provider before taking any type of herbs during pregnancy, since many of these herbal remedies are self-prescribed based on the woman’s own information or belief.

The Use of Alginate in Lemon Extract Effervescent Powder Production

<p>Study on the use of alginate in lemon (Citrus medica var lemon) extract effervescent<br />powder production has conducted. The aims of the research are to determine the optimum<br />concentration of alginate used in lemon extract effervescent powder to produced best<br />product and acceptance consumen.The lemon extract effervescent powder formula<br />consisted of lemon extract powder, sucrose, aspartame, salt and effervescent mix (citric<br />acid-tartrat acid-sodium bicarbonat). The alginate used in this study was extracted from<br />Sargassum filipendula sea weed. The concentration of alginate used in lemon effervescent<br />powder production was varied from 1; 2; 3 and 4%. The parameters observed to see the<br />quality of the product were moisture content, ash content, pH, viscosity and organoleptic </p><p>of dietary fiber, sugar content, vitamin C content, total titratable acids, TPC and E.Coli<br />to the best product. The result showed that the higher the concentration of alginate used<br />in lemon effervescent powder production, the higher viscousness and the lower the<br />organoleptic value. The optimum concentration of alginate used in the lemon extract<br />effervescent powder processing was 1%. The characteristic this product 7.60% moisture<br />content, 0.86% insoluble dietary fiber , 7.92% soluble dietary fiber, 3.74% sugar content,<br />55,26 mg/100 g vitamin C, 134.15 mL 0.1 NaOH/100 mL total titratable acids, 20 cPs<br />viscosity, <2.5x102 coloni/mL TPC and E.Coli negative.<br />Keywords: Alginate, characteristic, effervescent powder, lemon extract</p>

First report of Citrus bent leaf viroid in the United Arab Emirates.

Citrus species are among the three top fruit trees in the United Arab Emirates (UAE), with a combined total pro- duction of 12230 tons in 2011. Leaf samples were collected from four lemon (Citrus lemon L.) and five sweet orange (C. sinensis (L.) Osbeck) groves located in Al-Ain (south east of Abu Dhabi, UAE). Sampled trees showed weakened growth, but no typical symptoms of viroids and were tested for the presence of viroids by multiplex RT-PCR using two sets of primers specific for Citrus exocortis viroid (CEVd) and Cit- rus bent leaf viroid (CBLVd) (Al-Harthi et al., 2013). Testing disclosed the association of CEVd with 15 of 16 lemons in four groves, and with 18 of 18 sweet oranges in five groves. CBLVd was detected in six of 16 lemons in three groves and in five of 18 sweet oranges in three groves. To sequence PCR products, simplex RT-PCR was carried out with each primer set and two positive samples for CEVd and two for CBLVd. Amplifications produced fragments of the expected size, 371 bp for CEVd and 234 bp for CBLVd. PCR products were pu- rified and sequenced by Macrogen (Korea). CEVd sequences from the UAE were identical to each other and shared 99% nucleotide similarity to CEVd isolate CEVd-XNM-XY (Gen- Bank accession No. DQ431993), while the CBLVd sequence was identical to that of CBLVd isolate 201-1-2 Uy (accession No. AF428053). Sequences of both viroids from the UAE were deposited in GenBank (accession No. pending) This is the first record of CBLVd in the UAE. Presence of citrus viroids in Al-Ain, the most important agricultural area in the UAE, necessitates a larger scale study to characterize their distribution, pathogenicity and economic impact.

Small scale Coffee Farmer’s Response towards Management of Coffee Pest through Field Level Techniques

Coffee among the Nepalese farmers is one of the breaks-through from the traditional subsistence food crops to agrobased industrial crop. It was planted under multi cropping pattern with fruits species; Musa paradiciaca L (banana), Citrus lemon (Lemon), Artocarpus heterophyllus (jack fruit), Pyrus pyrifolia (pear), and Psidium guajava L (guava), fodders species, cereals and vegetables. Coffee farmers of Gulmi and Lalitpur tried to manage the orchards through shade management, intercropping, optimum manuring, and protection from pests. For this, farmers adopted various management techniques; handpicking and destroying, use of local pesticides, use of pheromones trap. More than 90 % of the coffee farmers were used local pesticides but with random composition and amount. Most preferred botanicals at farmer’s level are; Allium sativum L., Allium cepa L., Azadirachta indica, Eupatorium adenophorum, Utrica dioca L. Artemesia indica, Zanthoxylum Zanthoxylum. Though, these techniques were applied, farmers still were not successful fully to overcome the problem of White Stem Borer (Xylotrechus quadripes). This might be due to untimely application and not proper composition to prepare in large quantity. This prepared pesticide was only effective to control small and soft bodied insects. The using of botanicals was observed to reduce the chances of pest attack and found a significant step toward green pesticides.Journal of Institute of Science and Technology, 2014, 19(2): 37-44

Biochemical characterization of the primary metabolism and antioxidant defense systems of acidic and acidless citrus genotypes during the major stages of fruit growth

Fruits are consumed not just for their taste but also their nutritional value. The major primary metabolites in fruit are sugars and acids, whose contents change during fruit growth and determine ultimate fruit quality. Fruits are also a source of antioxidant metabolites, which are important to human health due to their role in reducing risk of cancer and cardiovascular diseases. Antioxidants are equally important in the plant as they help fight against oxidative stress. Here we investigated the consequences of changes in the primary metabolism in acidic and acidless citrus genotypes during the major stages of fruit growth on the expression of antioxidant enzymes and the markers of cellular oxidation (hydrogen peroxide, malondialdehyde) in acidless (Iaffaoui orange and sweet lemon) and acidic (Salustiana orange and Villafranca lemon) citrus fruits. Glucose and fructose were the major sugars in the acidless lemon. Sucrose was the major sugar in the acidic lemon. Oranges shared a balance of glucose, fructose and sucrose. Malic and citric acid concentrations were higher in acidic lemons than acidless fruits. Acidic genotypes had higher hydrogen peroxide concentrations than acidless genotypes, whereas MDA concentrations were higher in oranges than in lemons. Specific activities of ascorbate peroxidase, catalase, superoxide dismutase and dehydroascorbate reductase were on the whole higher in acidic than acidless fruits. Principal component analysis revealed between-genotype divergence in antioxidant system, giving three groups: acidic lemons, acidless lemons, and oranges.

Green Synthesis and Antimicrobial Activity of Monodispersed Silver Nanoparticles Synthesized Using Lemon Extract

A simple, environmentally benign green synthesis of silver nanoparticles was achieved using lemon fruit extract (Citrus lemon). The synthesized silver nanoparticles were characterized using UV-Vis spectroscopy, infrared spectroscopy, powder X-ray diffraction, and transmission electron microscopy. The predominantly spherical monodispersed 2–10 nm sized silver nanoparticles were obtained for the first time using lemon extract. The antimicrobial activity of silver nanoparticles was also explored. Lemon extract–mediated synthesis is cost efficient, eco-friendly and an easy alternative to conventional methods of silver nanoparticles synthesis.

Pest Control in Green Gram Seeds (<i>Vigna radiata</i>) by Using Plant Extracts

A experiment was conducted to investigate the efficacy of different plant derivatives against the development of the green gram pest Callosobruchus chinensis (L). fed on green gram seeds Vigna radiate for one month period. The leaf extracts of lemon (Citrus lemon), mint (Mentha arvensis) and black pepper seed (Piper nigram) powders were evaluated for their growth, adult mortality and oviposition inhibition of Callosobruhus chinensis. The results revealed that the extracts of all the three plant products caused a considerable reduction in the number of bruchids. Among the treatments Piper nigram were found to be effective in destroying the pest.

PEST CONTROL IN GREEN GRAM SEEDS ( Vigna radiata ) BY USING PLANT EXTRACTS

A experiment was conducted to investigate the efficacy of different plant derivatives against the development of the green gram pest Callosobruchus chinensis (L). fed on green gram seeds Vigna radiate for one month period. The leaf extracts of lemon ( Citrus lemon ), mint ( Mentha arvensis ) and black pepper seed ( Piper nigram ) powders were evaluated for their growth, adult mortality and oviposition inhibition of Callosobruhus chinensis . The results revealed that the extracts of all the three plant products caused a considerable reduction in the number of bruchids. Among the treatments Piper nigram were found to be effective in destroying the pest.

Pest Control in Green Gram Seeds (<i>Vigna radiata</i>) by Using Plant Extracts

A experiment was conducted to investigate the efficacy of different plant derivatives against the development of the green gram pest Callosobruchus chinensis (L). fed on green gram seeds Vigna radiate for one month period. The leaf extracts of lemon (Citrus lemon), mint (Mentha arvensis) and black pepper seed (Piper nigram) powders were evaluated for their growth, adult mortality and oviposition inhibition of Callosobruhus chinensis. The results revealed that the extracts of all the three plant products caused a considerable reduction in the number of bruchids. Among the treatments Piper nigram were found to be effective in destroying the pest.

FcWRKY70, a WRKY protein of Fortunella crassifolia, functions in drought tolerance and modulates putrescine synthesis by regulating arginine decarboxylase gene

WRKY comprises a large family of transcription factors in plants, but most WRKY members are still poorly understood. In this study, we report functional characterization of a Group III WRKY gene (FcWRKY70) from Fortunella crassifolia. FcWRKY70 was greatly induced by drought and abscisic acid, but slightly or negligibly by salt and cold. Overexpression of FcWRKY70 in tobacco (Nicotiana nudicaulis) and lemon (Citrus lemon) conferred enhanced tolerance to dehydration and drought stresses. Transgenic tobacco and lemon exhibited higher expression levels of ADC (arginine decarboxylase), and accumulated larger amount of putrescine in comparison with wild type (WT). Treatment with D-arginine, an inhibitor of ADC, caused transgenic tobacco plants more sensitive to dehydration. Knock-down of FcWRKY70 in kumquat down-regulated ADC abundance and decreased putrescine level, accompanied by compromised dehydration tolerance. The promoter region of FcADC contained two W-box elements, which were shown to be interacted with FcWRKY70. Taken together, our data demonstrated that FcWRKY70 functions in drought tolerance by, at least partly, promoting production of putrescine via regulating ADC expression.

Chemical composition, insecticidal and biochemical effects of essential oils of different plant species from Northern Egypt on the rice weevil, Sitophilus oryzae L.

The extensive use of synthetic insecticides and fumigants for control stored-product insects has led to the development of resistance. Essential oils from aromatic plants may provide proper alternatives to currently used insect control agents. Essential oils from 20 Egyptian plants were obtained by hydrodistillation. The chemical composition of the oils was identified by gas chromatograph/mass spectrometer. Fumigant and contact toxicities of the essential oils were evaluated against Sitophilus oryzae. The inhibitory effects of the essential oils on acetylcholinesterase and adenosine triphosphatases activities were examined. The oils were composed of monoterpene hydrocarbons (i.e., limonene, sabinene, β-pinene and γ-terpinene) and oxygenated monoterpenes (i.e., terpinen-4-ol, β–thujone, 4-terpineol, α-citral and 1,8-cineole) with the exception of the oil of Schinus terebinthifolius which was contained sesquiterpenes, and the oil of Vitex agnus-castus which contained similar amounts of monoterpenes and sesquiterpenes. In the fumigation assay, the oils of Origanum vulgare (LC50 = 1.64 mg/L air), Citrus lemon (LC50 = 9.89 mg/L air), Callistemon viminals (LC50 = 16.17 mg/L air), Cupressus sempervirens (LC50 = 17.16 mg/L air), and Citrus sinensis (LC50 = 19.65 mg/L air) showed high toxicity to S. oryzae. In the contact assay, the oils of Artemisia judaica, C. viminals, and O. vulgare caused the highest toxicity to S. oryzae with LC50 values of 0.08, 0.09, and 0.11 mg/cm2, respectively. The oil of A. judaica (I50 = 16.1 mg/L) invoked the highest inhibitory effect on AChE activity, while the oils of C. viminals and O. vulgare were the most potent inhibitors to ATPases activity with I50 values of 4.69 and 6.07 mg/L, respectively. The results indicate that the essential oils of A. Judaica, O. vulgare, C. limon, C. viminals, and C. sempervirens could be applicable to the management of populations of S. oryzae.

Humic Acid–Like Substances Extracted from Compost Improve Fe Nutrition of Lemon Grown on Calcareous Soil: An Environmentally Safe Approach

The short-term effectiveness of soil-applied humic acid–like substances [naturally complexed or uncomplexed with iron (Fe)] extracted from composted poultry (HLSP) and sheep (HLSS) manures in preventing lime-induced Fe chlorosis in Eureka lemon (Citrus lemon L.) cuttings grafted on sour orange (Citrus aurantium L.) was investigated and compared with the commonly applied ethylenediamine di-2-hydroxyphenyl acetate ferric (FeEDDHA). Treatments were untreated plants and plants fertilized with FeEDDHA, HLSP, and HLSS injected into the soil at a total rate of 25 mg Fe per plant each. Chlorophyll concentration index (CCI) of the youngest fully expanded leaves, growth vigor, and leaf Fe concentration were measured. HLSP and HLSS, similar to FeEDDHA, resulted in significantly greater CCI values, growth vigor, and leaf Fe concentration compared to untreated plants. HLSP and HLSS offer potential alternative to FeEDDHA to prevent lime-induced Fe deficiency in Eureka lemon. Concentrates of HLSP and HLSS can be commercially prepared to offer an inexpensive and environmentally safe product.

Phenolic content, antioxidant activities and stimulatory roles of citrus fruits on some lactic acid bacteria

In this study, phenolic compounds and antioxidant activities in citrus fruits and their peels were determined, and their stimulatory roles on some lactic acid bacteria were investigated. Phenolic compounds in citrus fruits such as mandarin, lemon, orange and grapefruit were determined either in the juices or in the peel extracts. Total phenolic content was determined in a spectrophotometer at 685 nm using the adapted Folin-Ciocalteu method. Total flavonoid content was measured using LC/MS (liquid chromatography-mass spectrometry). The effects of the fruit juices and peel extracts on the selected lactic acid bacteria (Lactobacillus delbrueckii NRRL B5448, Lb. casei NRRL B1922, Lb. acidophilus NRRL B4495) were investigated. The tested lactic acid bacteria were significantly affected by chlorogenic acid, hesperidin, naringin and caffeic acid compared to the control samples (P?0.05). Antioxidant properties of fruit samples were also measured using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. The phenolics positively affected the metabolism of bacteria, with the stimulatory effects of the assayed samples being influenced by the phenolic profile.

ANALYSIS OF GENETIC DIVERSITY IN TUNISIAN CITRUS ROOTSTOCKS

Breeding and selection of new citrus rootstocks are nowadays of the utmost importance in the Mediterranean Basin because the citrus industry faces increasing biotic and abiotic constraints. In Tunisia, citrus contributes significantly to the national economy, and its extension is favored by natural conditions and economic considerations. Sour orange, the most widespread traditional rootstock of the Mediterranean area, is also the main one in Tunisia. In addition to sour orange, other citrus rootstocks well adapted to local environmental conditions are traditionally used and should be important genetic resources for breeding. Prior to initiation of any breeding program, the exploration of Tunisian citrus rootstock diversity was a priority. Two hundred and one local accessions belonging to four facultative apomictic species (Citrus aurantium, sour orange; Citrus sinensis, sweet orange; Citrus limon, lemon; and Citrus aurantifolia, lime) were collected and genotyped using 20 nuclear SSR markers and four InDel mitochondrial markers. Sixteen distinct Multi-locus genotypes (MLGs) were identified and compared to references from French and Spanish collections. The differentiation of the four varietal groups was well-marked. Each group displayed a relatively high allelic diversity, primarily due to very high heterozygosity. The Tunisian citrus rootstock genetic diversity is predominantly due to high heterozygosity and differentiation between the four varietal groups. The phenotypic diversity within the varietal groups has resulted from multiple introductions, somatic mutations and rare sexual recombination events. This diversity study enabled the identification of a core sample of accessions for further physiological and agronomic evaluations. These core accessions will be integrated into citrus rootstock breeding programs for the Mediterranean Basin. (Resume d'auteur)