Main Objectives of Breeding Programmes
New Mandarin and Mandarin-like Cultivars Released in the Last 15 Years
The first examples of citrus breeding programmes are found in Italy at the end of the XIX century when very strong infections of Phytophtora Spp destroyed all trees of orange (Citrus sinensis L. Osbeck), lemon (C. limon L Burm. f.) and mandarin (C. deliciosa Ten.), which at that time were propagated by seed, and in Florida when a frost caused huge damages to the citrus industry.
The Phytophtora problem was solved by using sour orange (C. aurantium L.) as rootstock, while Swingle and Webber in Florida tried to introduce the cold resistance character of Poncirus into orange. It is known that no seedling producing edible fruits was obtained among this progeny, consisting of numerous inter-generic hybrids, but the citrange "Troyer" and "Carrizo" were selected, which were later on and still are much used as rootstocks.
Usual methods of Citrus breeding, and therefore also of mandarin breeding, are the singling out and selection of natural or induced mutations, the nucellar selection and the hybridisation.
The singling out and selection of natural improved mutants have always carried out a fundamental role in the development of the Citrus industry in the world. Meaningful examples of mutants are the satsuma varieties "Ueno" and "Miyagawa", the mandarin varieties, "Tardivo di Ciaculli" and "Avana seedless" and the clementine varieties "Arrufatina", "Clemenpons", "Hernadina", "Marisol", "Nour", "Nules", "Oronules" "Comune ISA", "Fedele", "Spinoso", "Rubino" e "Tardivo.
Treatments by mutant agents, such as chemical substances or ionising rays, can induce artificial mutations. For instance, bud woods of the clementine "Monreal", treated by gamma rays, produced several types of mutants, among which the almost seedless varieties "Monreal verde" and "Monreal rosso" that grow well even in the areas where the clementine "Comune" grows with difficulty.
If poly-embryonic genotypes are used in crossing as female parent, several nucellar seedlings similar to the mother plant are produced and very few or no hybrids. This characteristic, which is very frequent in most of the cultivated citrus species, allows to obtain virus free seedlings similar to the mother plant (even if infected) and also to select improved mutants which can be obtained by the nucell. The citrus improvement by nucellar selection takes a lot of time because of the very long juvenile phase, the late start into bearing and the high thorniness. The wait is often repaid with the singling out of some seedlings better than the parent both for yield efficiency and fruit quality. The satsuma varieties "Mihu" and "Okitsu" are nucellar selections of "Miyagawa". In Italy, the Istituto Sperimentale per l'Agrumicoltura of Acireale (ISA) obtained several nucellar selections from different citrus species or clone and, as regards mandarin, the most diffused originated from "Mandarino tardivo di Ciaculli" (nuc.60-22A-2, nuc.60-22A-7, 19 CN. L, 18 CN. L, 3DN6 N L.) and "Mandarino Avana apireno" (nuc. 62- Ap-9, nuc.-62-Ap-14).
The hybridisation to create new genotypes is conditioned by the heterozygous, which causes a strong variability of the characters in the progeny, by the nucellar embryony and by the long non productive juvenile phase which prevents carrying out the selection of the seedlings before they are 5 - 7 years old. In any case the best results of hybridisation in the Citrus species were obtained by artificial cross of various mandarin-like species. Important examples of hybrid selections are: In Italy "Palazzelli", "Primosole", "Simeto", "Desiderio", "Bellezza" and "Sirio"; In U.S.A. "Kara", "Wilking", "Kinnow", "Sunburst" and "Fortune"; In Israel "Yafit", "Norit" and "Edit"; in Japan "Nankou", "Hakaya", "Tsunokaori", "Benimadoca", "Ariake", "Amakusa", "Hareyaka", "Mihocore", "Yoku" and "Shiranuhi", which are almost all hybrids between satsuma, clementine or mandarin-like. Other important hybrids are those which can be obtained by the crossing between mandarin-like and grapefruit, that is the tangelos, and by mandarin-like and sweet orange which are called tangors. These hybrids have been largely cultivated and it is sufficient to mention the tangelos "Orlando", "Minneola", "Nova", "Mapo" and "Cami"; the latest two diffused in Italy. As regards the tangors, only the Japanese "Kiyomi" variety, obtained by artificial cross, was diffused, while much more important are those ones considered natural hybrids such as "Ellendale" in Australia, "Temple" in U.S.A., "Iyo", "Miyauki Iyo" and "Otani Iyo" in Japan, "Murcott" in Brazil, "Ortanique" in Morocco and more recently also in Italy and other Mediterranean countries.
Artificial hybridisation to create triploids is a promising method for production of seedless cultivars in citrus and thus in mandarin improvement programmes. In fact the female and male gametes of triplod genotypes are sterile because of the distorted trim of chromosomes. Triploid hybrids can be produced by the cross between female tetraploid parents and diploid male parents. But by this kind of cross only few hybrids and many nucellar seedlings are produced due to the high polyembryony level of the tetraploid female parent. On the contrary if monoembryonic zygotic diploid genotypes as female parent and tetraploid genotypes as male parent are used, several immature seeds are produced. The immature embryos, rescued and grown in vitro, generate triploid hybrids producing seedless fruits. In Italy the ISA has recently introduced "Tacle", an interesting triploid clementine x Tarocco hybrid, and in Israel the spontaneous triploid hybrid "Winola" was selected among a population of diploid hybrids between the mandarin "Wilking" and the tangelo "Minneola".
The use of modern biotechnologies based on in vitro culture of individual cells, of protoplasts, of tissues and on recombining DNA, allows to overcome some of the limiting factors of conventional breeding. In fact it gives the possibility of creating new genotypes by the direct transfer of useful genes and of carrying out the selection at cellular and molecular level.
Most citrus species are able to regenerate plants in vitro by organogeny from explants of cotyledons, epicotyls, buds, roots and juice vesicles. The rootstocks Citrange "Troyer", "Carrizo" and "Flying Dragon" are normally propagated since several years from axillary's buds. In the case of polyembryonyc Citrus it is possible to regenerate plants by somatic embryogenesis from the nucell tissue.
Through the in vitro culture of undeveloped ovules extracted from ripe fruits, (in vitro) embryogenic callus, embryos and plantlets from polyembryonic citrus species and varieties which produce seedless fruits can be obtained . These ovules are a first phase of the seeds that later on are not able to grow due to lack of fertilisation. They contain several nucellar embryos in the first phase of development, which if cultivated in vitro in proper substrates, originate the cycle of regeneration ovule-callus-embryo-plant. Through this technique, utilised especially in Italy (ISA), Japan, USA, several somaclonal varieties and selections of different citrus species were obtained.
The mutation of cells grown in vitro are defined somaclonal variation. This phenomenon is of great importance, as important as the natural mutations, because small positive genetic modifications into the somaclones can be caused, such as thorn-free, less vigour, shorter phase of juvenility, earlier starting into bearing, better yield efficiency and fruit size, earlier ripening, without modifying the most important peculiarities of the variety or the species.
Another important technique is the somatic hybridisation, which consists in the fusion of two protoplasts, one originated from embryogenyc callus and the other from leaf-mesophyll. The fusion is made through the use of the polyethylene glycol (PEG) or through electrofusion, which is based on the potential differences between electric fields. Therefore the somatic hybrids are allotetraploid (2n + 2n = 36 chromosomes) having entirely the chromosomes of the two genotypes. Many somatic hybrids were obtained in Florida, Japan, Israel, Spain and Italy. These tetraploid plants may have direct cultivar potential; however, their greatest value will be as pollen parents to be crossed with selected monoembryonic diploids to produce seedless triploids.
A hexaploid somatic hybrid has recently been obtained in China from electrofusion between diploids of Citrus sinensis and its sexually incompatible relative, Clausena lansium. This is the first report of hexaploid somatic hybrid plant regeneration from fusion between diploids in Aurantioideae
The somatic hybridisation is very important for creating new rootstocks. In Florida somatic hybrids have been obtained between rootstocks belonging to the genus of citrus or citrus allied, to incorporate in one single plant the characteristics of resistance to "Tristeza", to Phytophtora ssp., to nematodes or to calcareous soil, which are separately present in one of the two rootstocks.
The main objectives of the mandarin breeding programmes carried out by the most important research institutions in the world are: enlargement of the ripening season (earlier and later ripening cultivars), seedlessness, easy peeling, high rind colour, low tendency to alternate bearing, good flavour, better standardization of the fruit (shape and size), of the fruit chemical composition and of its post-harvest behaviour and resistance to the most dangerous pests and diseases.
Because most of the above mentioned traits can be found as natural mutations, especially those ones regarding the fruit, many of the actual cultivars were singled out by private farmers or nurserysts though officially they were often introduced or released by scientific institutions. Same kind of mutations can be obtained by mutant agents, but more frequently and in a much more limited space than it happens in nature.
A programme for developing seedless mutants of existing cultivars is carried out at the University of California - Riverside (UCR) by irradiating buds of seedy but promising cultivars. UCR identified six low seedy very promising mutant selections, actually under evaluation in mixed plantings. Same kind of programme are carried in China at the Cash Crop Station, Xiangxi, where "Fuyu 28" selection was obtained from irradiated (gamma rays) buds of "Ponggan"; at Guandong Fruit Research Institute which identified some promising seedless selections and at Changqing Fruit Farm, Guandong, which recently released the "Huaqing Seedless" and "Huaqing Few Seeded" varieties.
Another approach to developing seedless cultivars involves hybridisation between diploid and tetraploid to produce triploids, which are always essentially seedless, or to produce male sterile hybrid seedlings. The conventional cytological method for triploid identification is a laborious technique involving the preparation of root tips for chromosomal analysis. A useful technique (digital densitometry of isozymes) for distinguishing triploid citrus from large populations of seedlings both quickly and cheaply was set up by the Central Queensland University, in Australia. Interesting studies have been carried out in Japan on the inheritance of seed number and pollen yield in hybrid progenies resulting from crosses involving cultivars of different citrus species, which singled out a positive correlation between mean seed number/fruit in the two parents and that in their progenies. The UCR in USA and ISA in Italy are conducting breeding programmes to produce triploids hybrids and have recently released "Gold Nugget" and "Tacle" and "Clara" cultivars respectively. The UCR has identified seed-specific genes in mandarins (chimerical gene) which if introduced in the mandarin genomic DNA, transgenic mandarin plants could be regenerated.
The inheritance of citrus fruit peeling was studied in a large number of seedlings derived from several crosses among different Citrus species and types, at Fruit Tree Research Station, Kuchinotusu Nagasaki, in Japan. Varieties of mandarins, tangerines, tangor, Naruto, Hyuganatsu and most tangelos tend to produce "loose skin" or easy peeling progenies. Grapefruit, "Hassaku", "Kawachi-bankan", "Tosa-buntan" and "Natsumican" produce half of their progeny "compact skin" and half "loose skin". Crosses between sweet orange and mandarin yielded "loose skin" progeny at high frequency (87%).
Cold resistance is an important goal of citrus breeders. Recent studies conducted in China at the Department of Horticulture, Huazhong University, Hubei, showed that cold-tolerance is controlled by multigenes. Mandarins as a group and especially the "Changsha" mandarin and "Owari" satsuma, have been recognised as cold-tolerant and tend to produce tolerant progenies. The clementines "Robinson", "Page", "Nova" and the newly released "Ambersweet" are also considered cold-tolerant .
Ine China, the mandarin variety Jiouyuezao (C. reticulata) is described in the Jiangxi Province as very hardy germplasm, the tree surviving temperatures as low as -13.4°C, while the mandarins "Tuanianiju" and "Bendizao" and the Satsuma "Xingjin" in Hunan Province are considered hardy because did not suffer damages at -12.1 C°.
In Japan the tangor cultivars "Seihou" and "Tsunokaori" and the mandarin "Hayaka" have been pointed-out as resistant to scab ( Elsinoe fawcetti) by the Fruit Tree Research Station, Nagasaki, as well as the cultivar "Kousyun Ponkan" by the Fruit Tree Research Station, Shimizu, Shizuoka, while in China (Hubei Province) the new released mandarin "Egan" is also considered highly resistant. In Florida the USDA-ARS indicated the "Fallglo" cultivar as resistant to another agent (Sphaceloma fawcetti) causing scab disease.
In Japan the tangor "Kiyomi" has been recently pointed out as resistant to canker (Xanthomonas axonopodis pv citri) by the National Institute of Fruit Tree Science, Nagasaki, while "Nankou" and "Kousyun Ponkan" have been considered resistant to the other agent of canker (Xanthomonas campestris) by National Institute of Fruit Tree Science and the Fruit Tree Research Station, Shizuoka respectively.
In Brazil, in a screening study on a large citrus germaplasm for tolerance to Xylella fastidiosa, the causal agent of citrus variegated chlorosis CVC, the "Murcott" tangor and "Mexerica do Rio", "Ponkan" and "Cravo" mandarins resulted resistant.
Not many examples of breeding programme for insect resistance exist. The Institute of Botany, Academia Sinicia, Taipei, Taiwan, recently obtained three putatively transgenic plants from excised nucelli of mandarin "Blanco" cv. Ponkan co-cultured with Agrobacterium tumefaciens containing a plasmid with the Coleoptera-specific insecticidal gene from B. thuringiensis ssp. Tenebrionis. The three plants expressing the gene are actually grown for further insect-resistance tests. In a field study conducted in the Indian Punjab to screen numerous citrus species and cultivars, the varieties Carrizo, Sacatan, Savage, Troyer, Yama Citrange, Citrumelo (P. trifoliate x grapefruit), Campbell Valencia, Pomary and Robidoux were found resistant to Phyllocnistis citrella and therefore considered an interesting source of germplasm for resistance to this insect.
The common objective of the breeding programmes is to create citrus rootstocks resistant or tolerant to pests and diseases, to increase the adaptability to different soil and environmental conditions, to impart to the scion high yield, superior fruit quality and size, and other essential traits.
The potential of conventional methods of improvement of citrus rootstock is limited by biological factors that inhibit breeding and selection, such as heterozygous and inbreeding depression, pollen and ovule sterility, sexual incompatibility, apomixes and nucellar polyembryony, juvenility. However the USDA, ARS, US Horticultural Research Laboratory has carried out over time a programme for new rootstock development that focused on sexual hybridisation at the diploid level to produce improved genetic combinations. It recently released two hybrids "US-852" [Changsha mandarin (C. reticulata) x English Large Flowered Trifoliate Orange (Poncirus trifoliata)] and "US-812" (Sunki mandarin x Benecke trifoliate orange), which make healthy trees, excellent fruit quality and are very productive.
The IVIA in Spain has released two rootstocks in 1998 and two in 2000 obtained by sexual hybridisation. They are "Forner Alcaide 5" (F&A 5) , "Forner Alcaide 418" (F&A 418), Forner Alcide 13" (F&A 13) and "Forner Alcaide 517" (F&A 517) which all are resistant or tolerant to CTV and salinity. Moreover the "F&A 5" (Cleopatra mandarin x P. trifoliata) is resistant to the citrus nematode and has good tolerance to calcareous soils and flooding. The "F&A 13" (Cleopatra mandarin x P. trifoliata) is susceptible to citrus nematode but highly tolerant to salinity and flooding. The "F&A 418" (Troyer citrange x common mandarin) is dwarfing rootstock with good tolerance to calcareous soils, susceptible to the citrus nematode and induces to scion big fruit on the grafted variety. The "F&A 517" (King mandarin x P. trifoliate) is also a dwarfing rootstock and has good tolerance to calcareous soils and salinity.
Somatic hybridisation by protoplast fusion techniques is a new way to create new improved citrus rootstocks which can overcome the barriers imposed by the reproductive peculiarities of citrus. Most of the scientific institutions involved in breeding for the rootstock improvement utilize this technology. It is well developed by University of Florida, IFAS, CREC, by CIRAD, in France, by I.V.I.A. in Spain, by ISA and Centro di Studio per il Miglioramento Genetico degli Agrumi, CNR, in Italy.
Sixty somatic hybrids (SH) have been produced by protoplast fusion at CREC, Florida. SH containing Flying Dragon germplasm were extremely dwarfed and precocious, those containing sweet-orange parentage were consistently resistant to Phytophtora, while hybrids of Fortunella, Citropsis, Atalantia, Microcitrus and Citrus ichangensis parentage were resistant to Radopholus citrophilus nematode. Moreover seeds from SH germinated well and produced vigorous seedlings.
CIRAD in France selected a vigorous and tristeza-resistant intergeneric somatic hybrid between Poncirus trifoliata and Citrus deliciosa, which is resistant to citrus tristeza closterovirus.
The biotechnologies applied to citrus breeding open new enthusiastic prospects for the improvement of the citrus industry, even if they can not give immediate results. Therefore, at present and in the near future, the conventional breeding methods remain at the base of the citrus breeding programmes.
The biotechnologies actually can give significant results in breeding by the transfer of genes which control the resistance to diseases, insects and herbicides, but their application for the improvement of quantitative traits, such as yield efficiency and fruit quality, do not seem to be immediate.
A balanced integration of the two methods of breeding, conventional and biotechnologies, is probably the best way to follow for the development of the citrus industry.
Of all the citrus cultivars officially released in the world over the last 15 years, the mandarin and mandarin-like are certainly the most numerous. As showed in the "Annex -list of the cultivars", 13 cultivars were released in China, 11 in Italy, 11 in Japan, 8 in Spain 4 in USA, 5 in Israel, 6 in Australia, 1 in France, 1 in New Zealand, 1 in Morocco,1 in Argentina.
Only few of them are successfully cultivated in the country where they were released and even a more limited number is afterwards disseminated to countries where a citrus industry exists.
In any case, my impression is that in general it takes too long before even important citrus cultivars and, therefore, mandarin and mandarin-like cultivars, are introduced into different countries to be tested in field trials and eventually made available to the citrus industry. The same thing happens for the rootstock cultivars.
It is very important for the citrus industry to have a large number of suitable cultivars adaptable to different climate and soil conditions and which increasingly meet the demands of the market. For this reason it is increasingly important for the breeding programmes to create new improved cultivars, suitable for specific area and/or resistant to different pests and diseases. On the other hand, it is also of great importance for each citrus producing country to introduce at the right time the new cultivars, released all over the world, to be tested in field trials.
The national projects carried out in Italy "Recommended fruit cultivars" and more recently "Recommended citrus cultivars" are significant examples. The aim of these projects is to continuously introduce into experimental fields, located in the most important fruit or citrus areas, the new cultivars released in Italy and all over the world, to be evaluated in comparison with the most grown cultivars. An official preliminary evaluation of the scion cultivars is carried out just after the first two cropping years and the final evaluation after five cropping years. As regards the rootstocks, a preliminary result is achieved four years after planting and the final result is obtained 6-7 years after planting. The results are officially published in specialised magazines and are taken very much into consideration by farmers and nurseries.
ANNEX
List and short description of the mandarin and mandarin-like cultivars released in the last 15 years
PRIMOSOLE (released in 1993 - Italy): Type: mandarin hybrid. Parentage: C. unshiu Miho x C. reticulata Carvalhais. Fruit size: Ø 7.0 cm, W 140 g. Shape: oblate. Seed: Seedless. Tree: low vigour. Season: mid-late Oct. Area of cultivation: Italy. Rootstocks: sour orange. Climate: tipical coastal area
DESIDERIO (released in 1996 - Italy): Type: mandarin hybrid. Parentage: C. unshiu Miho x C. clementina Comune. Fruit size: Ø 7.0 cm, W 90 g. Shape: oblate. Seed: Seedless. Tree: medium vigour. Season: mid Oct.- late Nov. Area of cultivation: Italy. Rootstocks: sour orange. Climate: tipical coastal area.
BELLEZZA (released in 1996 - Italy): Type: mandarin hybrid. Parentage: C. unshiu Okitsu x C. reticulata Carvalhais. Fruit size: Ø 8.0 cm, W 145 g. Shape: oblate. Seed: Seedless. Tree: medium vigour. Season: late Oct. - late Dec. Area of cultivation: Italy. Rootstocks: sour orange. Climate: tipical coastal area.
SIRIO: (released in 1996 - Italy): Type: mandarin hybrid. Parentage: C. unshiu Miho x C. clementina Comune. Fruit size: Ø medium-large, W 150 g. Shape: globose. Seed: Seedless. Tree: medium vigour. Season: early Nov. -late Jan. Area of cultivation: Italy. Rootstocks: sour orange. Climate: tipical coastal area.
SIMETO (released in 1993 - Italy): Type: mandarin hybrid. Parentage: C. unshiu Miho x C. deliciosa Avana apireno. Fruit size: Ø 9.0 cm, W 160 g. Shape: quite oblate. Seed: Seedless. Tree: medium vigour. Season: late Nov. - late Dec. Area of cultivation: Italy. Rootstocks: sour orange. Climate: tipical coastal area.
CAMI: (released in 1992 - Italy): Type: mandarin hybrid. Parentage: (C. clementina Comune x C. deliciosa Avana) x Mapo tangelo. Fruit size: Ø 6.5 cm, W: 125 - 150 g. Shape: spheroidal. Seed : Seedless. Tree: medium vigour, upright growth habit. Season: late Dec.-mid Mar. Area of cultivation: Italy. Rootstocks: Troyer citrange.
TACLE: (released in 1999 - Italy): Type: triploid hybrid mandarin. Parentage: C. clementina Monreal x C. sinensis Tarocco 4x. Fruit size: Ø 7.0 cm, W 150 - 180 g. Shape: oblate. Seed : Seedless. Tree: high vigour, upright growth habit. Season: early Jan.-late Feb. Area of cultivation: Italy. Rootstocks: Troyer and Carrizo citrange, sour orange, trifoliata orange, Flying Dragon, Alemow. Note: susceptible to warm wind.
CLARA: (released in 1994 - Italy): Type: tripoid hybrid mandarin. Parentage: C. clementina Monreal x C.sinensis Tarocco 4x. Fruit size: Ø 8 cm, W 200 - 250 g. Shape: oblate-globose. Seed: seedless. Tree: medium vigour, upright growth habit.. Season: late Jan. - mid Mar. Area of cultivation: Italy. Rootstocks: Troyer citrange.
FALLGLO: (released in 1987 - Florida): Type: mandarin hybrid. Parentage: Bower (C.reticulata x Orlando tangelo) x Temple (C. reticulata hybrid). Fruit size:Ø 8.0 cm. W: 150 - 180 g. Shape: oblate, flattened at the stylar end, small navel. Seed n°: 10-12. Tree: high vigour, upright growth habit. Season: late Oct. - late Nov. Rootstocks: Carrizo citrange, Swingle citrumelo. Note: resistant to Sphaceloma fawcetti.
GOLD NUGGET: (released in 2000 - California): Type: mandarin hybrid. Parentage: Wilking (C. deliciosa Willowleaf x C. nobilis King) x Kincy (King x Dancy tangerine). Fruit size: Ø 7.0 cm, W 150 g. Shape: oblate. Seed: seedless. Tree: medium vigour. Season: Jan.-Feb. Rootstocks: Carrizo citrange. Climate: tipical coastal area.
MOR: (released in 1991 - Israel): Type: tangor. Parentage: irradiated budwood of Murcott tangor. Fruit size: Ø 6.5 cm, W 120 g. Shape: oblate. Seed n°: 2-7. Tree: low vigour, upright growth habit. Season: mid Feb.
WINOLA: (released in 1992 - Israel): Type: spontaneus triploid hybrid mandarin. Parentage: Wilking (C. deliciosa Willowleaf x C. nobilis King) x Minneola tangelo. Fruit size: Ø 6-7 cm. W 115-160 g. Shape: oblate. Seed: seedless. Tree: medium vigour, spreading, dropping. Season: late Feb. - mid Mar. Rootstocks: sour orange, Poncirus trifoliata hybrids.
AMAKA: (released in 1996 - Japan): Type: mandarin hybrid. Parentage: Kiyomi tangor (Miyagawa satsuma x Trovita orange) x Encore (King x Willowleaf).
YOUKOU: (released in 1995 - Japan): Type: mandarin hybrid. Parentage: Kiyomi tangor (Miyagawa satsuma x Trovita orange) x C. reticulata Nakano 3 ponkan. Fruit size: W 250-300 g. Shape: oblate. Seed: seedless. Season: Jan.-Feb. Note: resistant to citrus scab (Elsinoe fawcetti) and citrus canker.
AFOURER (released in 1997 - Morocco): Type: mandarin hybrid. Parentage: Murcott tangor x unknown pollen parent. Fruit size: Ø 6 cm. W 80-90 g. Shape: oblate. Seed: Seedless. Season: mid-late Feb. Area of cultivation: Morocco, California. Rootstocks: sour orange, trifoliata orange.
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HAYAKA (released in 1991 - Japan): Type: mandarin hybrid. Parentage: Imamura satsuma x C. reticulata Nakano 3 Fruit size: W 150 g. Shape: oblate. Seed n°:few. Season: early-mid Dec. Note: resistant to citrus scab (Elsinoe fawcetti) and cold.
ARIAKE: (released in 1992 - Japan): Type: tangor. Parentage: C. sinensis Seike navel x C. clementina. Fruit size: Ø 6 cm, W 170-200 g. Shape: oblate. Seed: Seedless. Season: mid-late Dec. Tree: low vigour, spreading habit. Note: resistant to citrus scab (Elsinoe fawcetti).
MIHO-CORE: (released in 1994 - Japan): Type: mandarin hybrid. Parentage: Miho-wase satsuma x Encore (C. nobilis King x C. deliciosa Willowleaf) Fruit size: W 150 - 200 g. Shape: oblate. Seed: seedless. Season: mid-late Dec. Tree: low vigour, spreading growth habit.
NANKOU: (released in 1991 - Japan): Type: hybrid. Parentage: Miho-wase satsuma x C. clementina. Shape: sub-globose. Fruit size: W 130 g. Seed: seedless. Season: mid-late Dec. Note: resistant to Xanthomonas campestris.
AMAKUSA: (released in 1993 - Japan): Type: tangor. Parentage: (Kiyomi tangor x Okitsu Wase) x Page orange. Fruit size: W 170-200 g. Shape: oblate. Seed: seedless. Season: late Dec.- early Jan. Tree: medium vigour.
KOUSYUN PONKAN: (released in 1991 - Japan): Type: mandarin. Parentage: developed from nucellar seedlings Fruit size: W 130 g. Shape: oblate Seed n°: 5-15. Season: late Dec.- mid Jan. Tree: high vigour. Note: resistant to citrus scab (Elsinoe fawcetti), citrus canker (Xanthomonas campestris) and citrus tristeza closterovirus.
SEIHOU (released in 1991 - Japan): Type: tangor. Parentage: Kiyomi tangor x Minneola tangelo. Fruit size: W 200 g. Shape: globose. Seed: seedless. Season: mid-late Jan. Tree: medium vigour. Note: resistant to citrus scab (Elsinoe fawcetti).
HAREYAKA: (released in 1994 - Japan) Type: mandarin hybrid. Parentage: Encore (C. nobilis King x C. deliciosa Willowleaf) x C. reticulata Nakano 3 ponkan. Fruit size: W 170-250 g. Shape: oblate. Seeds n°: many (similar Encore). Season: Feb. Tree: high vigour, upright growth habit.
TSUNOKAORI (released in 1991 - Japan): Type: tangor. Parentage: Kiyomi tangor x Okitsu Wase satsuma. Shape: oblate. Fruit size: Ø 6 cm, W 160 g. Seed: seedless. Season: late Mar.-mid Apr. Tree: medium vigour, spreading growth habit. Note: resistant to citrus scab (Elsinoe fawcetti) and cold.
SUNSET (released in 1991 - Australia): Type: mandarin hybrid. Parentage: C. reticulata Imperial x Ellendale tangor. Seed n°: few. Shape: oblate. Season: early-mid.
ELOISE (released in 1993 - Australia): Type: C. reticulata
SUCCESS (released in 1992 - Australia): Type: C. reticulata.
MONARCH (released in 1994 - Australia): Type: C. reticulata
NOVA SL (released in 1995 - Australia): Type: tangelo
IrM1 (released in 1998 - Queensland): Type: tangor
BAY GOLD (released in 1993 - New Zealand): Type: tangelo.
RIPETRI: (released in 1988 - France): Type: Clementine tangerine. Fruit size: Ø medium. Shape: oblate. Season: early.
RISHON (released in 1993 - Israel): Type: mandarin hybrid. Parentage: Temple tangor x C. reticulata Mikhal. Tree: medium vigour. Shape: subglobose. Fruit size: Ø 6 cm, W 95 g. Season: late Sept.- early Oct.
SHANI (released in 1992 - Israel): Type: mandarin hybrid. Parentage: C. reticulata Wilking x C. reticulata Mikhal. Shape: oblate. Fruit size: Ø 6-7 cm, W 115-150 g. Seed n°: 1-9. Season: late Jan.-Feb. Tree: high vigour, spreading. Rootstocks: sour orange, Troyer citrange, Citrumelo, Rangpur lime.
ORAH (released in 1992 - Israel): Type: mandarin hybrid. Parentage: Temple tangor x C. reticulata Dancy. Fruit size: Ø 6-7 cm, W 90 -140 g. Seed n°: 8-29. Shape: oblate. Season: late Dec.-Jan. Tree: moderately spreading. Rootstocks: sour orange,Troyer citrange.
SPINOSO (released in 1997 - Italy): Type: clementine. Parentage: C. clementina Comune bud mutation. Fruit size: Ø 6.0 cm, W 80-90 g. Shape: slightly oblate. Seed: seedless. Tree: medium vigour, spreading, upright growth habit. Season: mid Oct.-mid Nov. Note: susceptible to exocortis viroid.
RUBINO (released in 1994 - Italy): Type: clementine. Parentage: C. clementina Comune bud mutation. Fruit size: Ø 5.5-6.0 cm, W:70-80 g. Shape: slightly oblate. Seed: seedless. Tree: medium vigour, dropping. Season: early Jan.-mid Feb. Rootstocks: sour orange. Note: susceptibility to exocortis viroid.
MARISOL ( Spain): Type: clementine. Parentage. C. clementina Oroval bud mutation. Fruit size: Ø 6 cm, W 110-120 g. Seed: seedless. Tree: open habit. Season: mid Oct. - mid Nov.
ARRUFATINA:(released in 1985 - Spain): Type: clementine. Parentage: C. clementina Nules bud mutation. Fruit size: Ø larger than Nules. Seed: seedless. Tree: medium vigour. Season: mid Nov.
ESBAL (released in 1985 - Spain): Type: clementine. Parentage: C. clementina Fina bud mutation. Fruit size: Ø 5 cm. Seed: seedless. Tree: medium vigour. Season: late Nov.
HERNANDINA (released in 1985 - Spain): Type: clementine. Parentage: C. clementina Fina bud mutation. Ø 5 cm. Seed: seedless. Tree: medium vigour. Season: early Jan - mid Feb.
ORONULES (released in 1990 - Spain): Type: clementine. Parentage: C. clementina Nules bud mutation. Fruit size: Ø 5.0 cm, W 80-90 g. Shape: slightly oblate. Seed: seedless. Tree: high vigour, open habit. Season: mid Jan.
(no pictures)
FEDELE: (released in 1988 - Italy): Type: clementine. Parentage: spontaneous mutation from C. reticulata Comune. Features like Comune except Season: two week earlier (mid Oct-mid Nov.).
CLEMENPONS: (released in 1996 - Spain) Type: clementine. Parentage: spontaneous mutation from Nules. Season: earlier than Nules.
LORETINA (released in 1996 - Spain): Type: clementine. Parentage: spontaneous mutation from Marisol. Season: earlier than Marisol.
SATSUMA (with picture)
CLAUSELLINA (released in 1984 - Spain): Type: satsuma. Parentage: C.unshiu Owari bud mutation. Fruit size: Ø 5 cm. Seed: seedless. Season: mid Jan.
(no pictures)
TEMPRANA (released in 2000 - Argentina): Type: satsuma. Parentage: spontaneous mutation from Okitsu. Season: ten days earlier than Okitsu.
BROWN'S SELECT (released in 1993 - Lousiania): Type:satsuma. Parentage: Kimbrough seedlings selection. Fruit size: medium-large. Seed: Seedless. Season: early-mid Oct.
KIMBROUGH (released in 1990 - Florida): Type: satsuma. Parentage: selection of o.p. seedllings of Owari. Seed: Seedless.
WUHEXUEGANLINGHAO (released in 1998 - China): Type: mandarin. Parentage: irradiation of Xueganlinghao. Fruit size: W 120-153 g. Seed: seedless. Season: early.
ZAOJIN JIAOGAN (released in 1990 - China): Type: satsuma. Parentage: Xingjin selection. Season: mid Sept.
DONGHUAMIJU (released in 1997 - China): Type:mandarin. Parentage: Nanfengmiju clone Shape: oblate. Fruit size: W 44 g. Seed: seedless. Season: late Oct.
GANPENG 1 (released in 2000 - China) Type: mandarin. Parentage: change seedling of Penggan. Fruit size: W 115 g. Seed: seedless. Season: mid-late Nov. Note: resistant to low temperature for a short time (-11 °C).
XUANNAN 1(released in 1991 - China). Type: mandarin. Parentage: Red selection (containing many seeds). Fruit size: W 86 g. Seed n°: 3. Season: late Nov.
FUYU (released in 2000 - China): Type: mandarin. Parentage: irradiation of Ponggan. Seed: Seedless. Season: late Nov.-early Dec. Note: resistant to drought and unfertile soil and to citrus canker.
LESHAN YIYUGAN(released in 1998 - China): Type:mandarin Parentage: selectionn of Yiyugan Fruit size: W: 315 g. Seed: seedless. Tree: compact. Season: early-mid Dec.
WANMI (released in 1991 - China): Type: mandarin. Parentage: Weizhou satsuma x C. sinensis S8. Fruit size: W: 120 g. Shape: subglobose. Season: mid-late Jan.
CHEXI WANLU: (released in 1995 - China) Type: mandarin Parentage: Pongan clonal selection. Fruit size: W 153 - 168 g. Shape: oblate. Seed n°: 5. Season: late Jan-mid Feb.
YANXI WANYOU(released in 1994 - China): Type: mandarin Parentage: sport of Pongan. Fruit size: W 153 - 168 g. Seed: seedless. Season: late Jan.-mid Feb.
MEIZHOU SUMMER JIAOGAN(released in 1993 - China): Type: mandarin Parentage: Jaogan selection. Fruit size: W 150 g. Season: mid May-mid June.
WUHE XUEGAN (released in 1997 - China): Type: mandarin. Parentage: selection of Xinsheng Xuegan. Fruit size: W:180-200 g. Seed: seedless.
TAY 1(released in 1997 - China): Type: mandarin Parentage: Ponkan spontaneous mutation. Fruit size: W large. Seed: seedless.
EGAN 1 (released in 1997 - China): Type: mandarin Parentage: Pongan selection Fruit size: W 130-175 g. Seed: more than Pongan. Note: high resistant to citrus scab (Elsinoe fawcetti).
