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INRA Morocco has an important citrus collection located in several sites in the Kingdom. Citrus germplasm offers a large resource for selecting within local lemon accessions of genes related to disease resistance, stress, production, fruit quality. Which are essential for genetic improvement. Some potential varieties may be of interest to producers. In the present study, twenty-three accessions of a lemon tree (Citrus limon [L.] Burm. F.) planted at El Menzeh collection, are characterized according to the IPGRI and UPOV citrus descriptors. Morpho-pomological variables showed a significant difference between lemon accessions. Only the morphological parameters of leaves, fruits and fruit peel color showed a high variability. Chemical analysis of the juices revealed significant differences among accessions. The data showed that acidity ranged from 0.1% for Sweet and Butnal lemons to 6.6% for Kennedy. While, the Kerkachi, Butnal, Cascade and Allen lemon accessions had the highest levels of both sugar and juice. Likewise, the accessions Doux Acid, Dellys and Kennedy showed fruits with an important size. The fruits of Lisbon, Eureka, Corregia, Ba Ahmed and Valencia had fruits with a low number of seeds or seedless. Our study showed that there was an acceptable pomological variability among the accessions of lemons cultivated in Morocco. Butnal, Allen, Cascade, Sçweet Acid, Dellys, Kennedy, Lisbon, Eureka, Corregia, Ba Ahmed and Valencia lemons were promising in terms of quality. This makes them an important genetic resource for any future lemon program to expand varietal diversification for improved productivity and competitiveness of citrus. Finally, the use of molecular markers is necessary to complete this work and for better differentiation of closely related individuals., African and Mediterranean Agricultural Journal - Al Awamia, No 135 (2022)

Cybridisation is a plant biotechnology tool, which can be used to improve the resistanc of citrus rootstocks to salinity. To validade this approach, cuttings of six diploid cybrids obtained by symmetric fusion as well as their parents were used: Willow leaf mandarin (Citrus deliciosa) + (C. macrophylla), Willow leaf mandarin (Citrus deliciosa) + Citrumelo 4475 (C. paradisi x P. trifoliata), Willow leaf mandarin (Citrus deliciosa Ten.) + Rangpur lime (C. limonia), F (Willow lead mandarin (Citrus deliciosa) + Rangpur lime (C. limonia)), Willow leaf mandarin (Citrus deliciosa) + C35 (C. sinensis x P. trifoliata), Willow leaf mandarin (Citrus deliciosa) + Citrandarin (C. reticula x P. trifoliata) and Poncirus trifoliata. The plants were subjected to different doses of NaCl: 0, 50, 100 and 150 mM. The evaluation of salinity effects on growth parameters and the comparison of Cl accumulation among the genotypes studied led us to conclude that all these parameters were affected. However, cybrids seemed to be tolerant, sensitive or "moderately tolerant" compared to the parental genotypes. Rangpur lime cybrids showed particularly a differential response to salinity. When the cybrid F expressed an impressive resistance, it was found that the other cybrid RL behaves in a similar way to that of the parents. (Texte intégral)

Increasing salinity in Mediterranean soils and the wide spread of citrus tristeza virus have challenged the use of sour orange (Citrus aurantium) and have accelerated the process of seeking alternative rootstocks. In the present study, nine cultivars of citrumelo (Citrus paradisi Macf. x Poncirus trifoliata (L.) Raf.) were evaluated for salt tolerance. Two month-old seedlings were raised under greenhouse conditions and irrigated with a half strength Hoagland solution supplemented with different concentrations of NaCl, i.e., 0 mM, 35 mM and 85 mM. Tolerance was assessed after two months of stress by measuring stem growth, number of leaves, fresh and dry weight organs and leaf water, chlorophyll and chloride contents. A differential behavior was noticed among the seedlings we studied. When using increased concentration of salt in irrigation water, all the parameters were significantly reduced except for leaf chloride content which highly increased in response to stress. At 85 mM, the cultivar SC2 showed a high tolerance resulting in less apparent leaf symptoms, higher growth and higher leaf chlorophyll content when compared to other seedlings. Similarly, the cultivar C4475-C was shown to be a strong root chloride excluder with less than 2.6% DW (dry weight) chloride accumulation at leaf level. By contrast, our results suggest that C4475-A and C4475-B are salt sensitive cultivars regarding to all the parameters studied while the other citrumelos were considered as moderately tolerant. (résumé d'auteur)

Soil and water salinity is an important abiotic stress that can affect both production and quality of citrus. The use of tolerant rootstocks in these conditions would be the solution the most used. The objective of this study was to compare in vitro behavior of four citrus genotypes in terms of tolerance to salinity. The genotypes used were 'Cleopatra' mandarin, 'Chios' mandarin, 'Shamouti' orange and 'Star Ruby' grapefruit. Salt tolerance was evaluated by determination of callus and suspension cells growth, the fresh and dry weight, water content and chloride ion content after one month of culture in solid and liquid media supplemented with NaCl at different concentrations: 50, 100, 150 and 200 mM. At 0 mM NaCl, the results revealed that callus of the four genotypes tested have a similar behavior in term of tolerance to salinity as the suspension cells. However, a differential behavior was observed at high salt concentrations depending on genotypes and the nature of medium. (Texte intégral)