The newly developed citrus cultivar, ‘Miraehyang’, was bred at the Citrus Research Center of the National Institute of Horticultural and Herbal Science (Jeju, Korea) by crossing ‘Ehime Kashi No.28’ (maternal parent) and ‘Hayaka Ponkan’ (paternal parent). The first fruiting of ‘Miraehyang’ occurred in 2016, and field evaluations were conducted until 2021. After final selection in 2021, the cultivar was officially registered for plant variety protection in 2024. The tree exhibits strong vigor, an open growth habit, and high fruit-bearing capacity. When grown in a plastic greenhouse, ‘Miraehyang’ showed minimal occurrence of puffing and fruit-cracking. New shoots emerged in late March, and flowering began in late April, with full bloom occurring in mid-May. The average fruit weight was between 150-200 g, and the fruit shape slightly flattened with a small apex. Coloring started in mid-October and completed by mid-December, resulting in a deep orange hue. The fruit is rich in juice with thin membranes, providing a tender texture. Under unheated greenhouse conditions, the fruit matured in mid-to-late December and had a soluble solids content of 12-13°Bx and acidity of approximately 1.0%. Peel thickness averaged at 3.3 mm, similar to that of ‘Ehime Kashi No.28’, but with improved ease of peeling. This cultivar is male-sterile, producing seedless fruit when grown alone. Similar to its maternal parent, ‘Ehime Kashi No.28’, ‘Miraehyang’ is susceptible to citrus canker but resistant to scab. ‘Miraehyang’ is expected to gain high consumer preference due to its ease of cultivation, superior peelability, and outstanding fruit quality and appearance (Variety registration number: 10180).

The lemon cultivar ‘Jeramon’ is a nucellar seedling obtained through controlled pollination, with ‘Frost Lisbon’ as the seed parent and ‘Meyer’ as the pollen parent. ‘Jeramon’ had its first fruit set in 2012 and was selected in 2015 after evaluating its characteristics for three consecutive years. The ‘Jeramon’ tree was vigorous, upright-spreading, and flowered three times a year (mid-May to Early June, late June to early August, and early September). The average fruit weight was 120 g. The rind thickness was approximately 5 mm, which was thicker than that of common citrus cultivars, including Satsuma mandarin and late-maturing cultivars. The rind and pulp were pale yellow at full maturity. Total soluble solid ratio and acidity were 8.5% and 11°Brix, respectively, which were higher than that of ‘Frost Lisbon’. ‘Jeramon’ is self-compatible, producing approximately 10 polyembryonic seeds per fruit (Registration No. 9060).

In this study, we investigated the variety-dependent survival of citrus seedlings and analyzed the pomological characteristics of fruits and thorn lengths following irradiation with gamma rays. Scions from the seedlings of the following citrus varieties, ‘Yuzu’, ‘Noeulhyang’, ‘Sarahyang’, ‘Namgam’ (nucellar), and ‘Meiwakumquat’ irradiated with gamma rays at 0, 60, 80, and 100 Gy were grafted onto trifoliate orange. At 6 months after grafting, the survival rates of ‘Yuzu’ and ‘Noeulhyang’ exposed to 100 Gy were 49.5% and 34.8%, and that of ‘Sarahyang’ and ‘Namgam’ (nucellar) exposed to 80 Gy were 51.6% and 46.8%, respectively. ‘Meiwakumquat’ exhibited the lowest survival among the varieties used in this study. Therefore, we classified ‘Meiwakumquat’ as highly susceptible to gamma radiation; ‘Noeulhyang’, ‘Sarahyang’, and ‘Namgam’ (nucellar) as intermediately susceptible; and ‘Yuzu’ as the least susceptible. We assessed the effects of gamma radiation on the pomological traits in irradiated ‘Tambit1ho’ and ‘Yuzu’. Among the 72 irradiated ‘Tambit1ho’ seedlings, the average seed number (number of seeds per fruit) varied between 0 and 18.6, whereas that in the unirradiated seedlings was between 8 and 18. Among the irradiated seedlings, the average seed number was less than 1.0 in eight seedlings. In addition, we observed variations in weight, rind and segment hardness, and sugar and acid contents. The thorn length of the flush in unirradiated ‘Yuzu’ was between 1.3 and 6.0 cm, whereas that of flush in gamma-irradiated seedlings was between 0.1 and 6.1 cm. Among the irradiated ‘Yuzu’ seedlings, the thorn length was less than 0.1 cm in two seedlings.

The ‘Minihyang’ mandarin is a new hybrid of ‘Kinokuni’בPonkan’ bred at the Citrus Research Institute, National Horticultural and Herbal Science, Korea. It has a small fruit size (30-40 g) and a high sugar content (12-14°Brix). Herein, a chemical characterization of ‘Minihyang’ was conducted. Free sugar, which determines sweetness, is a key component of food taste. Analysis of free sugar showed that the most abundant component was sucrose (8.81±0.45 g/100 g), followed by glucose (1.23±0.11 g/100 g), and fructose (1.23±0.08 g/100 g). Among the 20 free amino acids analyzed, arginine and asparagine accounted for 71% of the total amino acid content, displaying both amino acids at the highest content of 77.14 mg/100 g. The major flavonoids in citrus fruits differ between varieties, showing the differences among cultivars. The flavonoid contents of ‘Minihyang’ were higher in the peel than in the flesh, and hesperidin was identified as the major flavonoid, with 1,133.7 and 689.8 mg/100 g extracted from the peel and flesh, respectively. Furthermore, nobiletin and tangeretin, which are only present in citrus species, were identified in the peel. Volatile component analysis revealed that limonene content, a characteristic component of citrus fruits, was highest in the flesh of ‘Minihyang,’ accounting for approximately 75-80% of all volatile compounds. Notably, the order was fresh limonene>terpinene>terpinolene. Overall, this study revealed many functional compounds in the ‘Minihyang’ mandarin hybrid.

A new citrus cultivar ‘Tamdosamho’ is a hybrid obtained from a cross of ‘Kiyomi’ (Citrus unshiu×Citrus sinensis, the seed parent) and ‘Sunburst’ (Citrus reticulate, the pollen parent) at the Citrus Research Institute of the National Institute of Horticultural and Herbal Science in 2004. ‘Tamdosamho’ had the first fruit set in 2010 and field evaluation has been conducted until 2012. The tree of ‘Tamdosamho’ was vigorous and had a lot of fruit bearing. The average fruit weight was 230g and its shape was flatten-oblate with a little neck. The fruit peel color was dark orange, and peel coloration began in mid-October and fully developed in early December. The fruit matured in mid-February from cultivation under plastic film house. Total soluble solid and acidity of which was 14.0 °Brix and about 1 % respectively. The thickness of the rind was about 2.5 mm on average and was thinner than that of satsuma mandarin (Citrus unshiu), so removing the peel was easy. This cultivar had characteristic of self-incompatibility and parthenocarpy and didn’t bear seeds from monoculture but if it be fertilized by the pollen of other cultivars could be seedy. In the case of cultivation in the open field, the fruits could be damaged by cold temperature and then ‘Tamdosamho’ is recommended for cultivation under plastic film house. (Variety registration number: 6158)