The intermediate breeding material ‘JJ625LG’ was developed to diversify the grain shape characteristics of Korean japonica rice cultivars. ‘JJ625LG’ was derived from a cross between ‘HR30198-AC33 (DGS79),’ a japonica breeding material with extra-long and spindle-shaped grains, and ‘Boramchan,’ a high-yielding japonica cultivar with excellent cultivation stability and medium-short and semi-round grains. By employing both bulk and pedigree breeding methods, strong selection pressure was applied to eliminate undesirable traits inherited from ‘DGS79,’ such as very late heading, long awns, and susceptibility to lodging. Consequently, elite lines with long spindle-shaped grains on a japonica background were selected. These lines subsequently underwent yield performance and local adaptability tests, during which their agronomic traits were comprehensively evaluated, leading to the final selection of ‘JJ625LG.’ The heading date of ‘JJ625LG’ was August 16th, three days later than that of ‘Nampyeong’. Its culm length was similar to ‘Nampyeong.’ ‘JJ625LG’ exhibited a higher number of spikelets per panicle, fewer panicles per plant, and heavier 1,000-grain weight than brown rice. Additionally, it showed strong resistance to bacterial blight (races K1, K2, and K3) but was susceptible to viral diseases and insect pests, indicating the need for further improvement in these areas. Its grain yield was comparable to that of ‘Nampyeong.’ With a brown rice grain length of 6.34 mm, ‘JJ625LG’ was classified as a long-grain type and had a grain length-to-width ratio of 2.64, reflecting a spindle-shaped morphology. It carried the GW2-gs3-qSW5 allele combination associated with grain shape, which is a genetic profile not found in existing Korean japonica cultivars. Although its milling recovery rate was similar to that of ‘Nampyeong,’ the presence of many broken rice due to its long grain shape resulted in a lower percentage of head rice. The eating quality of ‘JJ625LG’ was excellent, with its grains exhibiting the sticky and soft texture typical of japonica rice and receiving high scores in sensory evaluation. As the first intermediate breeding material in Korea with long and spindle-shaped grains in a japonica background, ‘JJ625LG’ is expected to contribute significantly to diversifying the traditionally narrow grain shape spectrum of Korean japonica rice cultivars (Registration No. 10166).

Bakanae disease, caused by various Fusarium species, poses a significant threat to global rice production, with its incidence increasing in major rice-producing regions. Currently, no rice varieties exhibit complete resistance to this disease. Enhancing resistance in rice cultivars could serve as a cost-effective and sustainable alternative to fungicide application. Developing resistant rice varieties may offer a practical solution to mitigate yield losses and reduce dependency on chemical treatments. ‘Jinokchal’ was derived from the cross between ‘Milyang299’, which harbors bakanae disease-resistant QTL qBK1. and ‘Baekokchal’ in 2014. A promising line, YR31624-5B-2, was then selected and designated as ‘Milyang366’ in 2019. The local adaptability test of ‘Milyang366’ was conducted at five locations from 2020 to 2022, and the cultivar was subsequently named ‘Jinokchal. ’ The heading date of ‘Jinokchal’ was August 13, classifying it as a medium-late maturing cultivar. The culm was 77 cm long and had 108 spikelets per panicle. The 1,000 grain-weight of brown rice is 22.7 g, which is heavier than that of ‘Sinseonchalbyeo’. This variety is resistant to blast, rice stripe virus, and bacterial blight, but susceptible to insect pests. The yield potential of ‘Jinokchal’ was approximately 497 kg/10a at the ordinary fertilizer level in the local adaptability test over three years. ‘Jinokchal’ is moderately resistant to bakanae disease and harbors the qBK1 gene derived from the tong-il type rice ‘Shingwang’ (Registration No. 8135).

The rice cultivar ‘Chamdongjin’ was developed to enhance the disease resistance of ‘Sindongjin’. ‘Sindongjin’, developed by the RDA in 1999, is a mega-variety with a unique grain size and excellent taste, and has been cultivated in the largest area in Korea since 2018. As ‘Sindongjin’ has been cultivated in a large area recently, problems such as pest damage are increasing, and the necessity to develop alternative cultivars is emerging. Accordingly, the multiple disease-resistant, mid-late maturing rice cultivar ‘Chamdongjin’, carrying the bacterial blight resistance gene Xa21 into the genetic background of ‘Sindongjin’, was developed. ‘Chamdongjin’ was developed by the backcrossing method using the donor parent ‘HR27195-59-3-5-5’, harboring the bacterial blight resistance genes Xa3+Xa21 and the recurrent parent ‘Sindongjin’. ‘Chamdongjin’ was selected through the pedigree method, yield trials, and local adaptability tests, with a high selection pressure for agronomic trait similarities with ‘Sindongjin’. In order to effectively improve the disease resistance, marker-assisted selection for disease resistance genes and bioassays for bacterial blight, blast, and stripe virus were performed in parallel. ‘Chamdongjin’ was confirmed to have three disease-resistance genes, Xa3+Xa21+Stvb-i. Most of agronomic traits of ‘Chamdongjin’ were similar to ‘Sindongjin’, while ‘Chamdongjin’ showed enhanced disease resistance against bacterial blight and panicle blast compared to ‘Sindongjin’. ‘Chamdongjin’, like ‘Sindongjin’, possessed a grain size-related gene, the gs3 allele, and exhibited larger grains than general Korean japonica cultivars. In addition, ‘Chamdongjin’ showed a similar or higher level of palatability compared to ‘Sindognjin’, indicating the excellent quality characteristics. In the genetic background analysis using 787 KASP markers, ‘Chamdongjin’ showed 96.3% homozygosity with ‘Sindongjin’, indicating that it had a more similar genetic background to ‘Sindongjin’ than to other existing cultivars. ‘Chamgdongjin’ is expected to be widely cultivated as an alternative to ‘Sindongjin’, which could maintain the brand value while preventing the disease damage caused to ‘Sindongjin’ (Registration No. 9310).

“Baromi2” is an improved resistant early maturing rice variety with floury endosperm, and is suitable for dry milling. This variety was developed in 2019 by crossing “Suweon542,” which is ideal for dry milling, and “Jopyeong” by the rice breeding team at the National Institute of Crop Science, Rural Development Administration. The heading date of “Baromi2” was July 27 in the Honam Plains, 17 d earlier than that of “Seolgaeng.” The culm length of “Baromi2” was 76 cm, which was almost the same as its check variety “Seolgaeng”; additionally, its panicle length, panicle number, and 1,000 grain-weight of brown rice were 23 cm, 11, and 18.4 g, respectively. “Baromi2” showed strong resistance against rice blast, bacterial blight, and stripe virus disease, but was susceptible to dwarf and brown and small brown planthoppers. The milled rice yield of “Baromi2” was approximately 475 kg/10a in the local adaptability test for 3 years in the late planting culture. The grain hardness of “Baromi2” with a floury endosperm was 2 and 3 times lower than that of “Seolgaeng” with opaque endosperm and “Jopyeong” with transparent endosperm, respectively. The rice flour of “Baromi2” exhibited superior physicochemical characteristics with respect to granule size and damaged starch content compared with any other check varieties. These results inferred that “Baromi2” was suitable for dry milling and for the processed rice industry, owing to its lower milling costs and eco-friendly milling methods (Registration No. 9052).

‘Jonong’ is an early maturing whole crop silage (WCS) japonica rice cultivar characterized by a short growth duration and numerous spikelets. It was developed to enhance the adaptability of WCS rice to double-cropping systems. ‘Jonong’ is derived from a cross between ‘Binhae Col.#1’ and ‘Deuraechan’; ‘Binhae Col.#1’ is a semi-early maturing China rice germplasm with numerous spikelets on dense panicles, whereas ‘Deuraechan’ is a high-yielding japonica rice cultivar with numerous spikelets on long panicles. To diversify the genetic variation and shorten the breeding period, an anther culture method was applied to the F₁ plants. ‘Jonong’ was selected through the pedigree method, yield trials, and local adaptability tests, with a high selection pressure for short growth duration and high biomass. The average heading date of ‘Jonong’ was August 1^st, which is 11 days earlier than that of ‘Nokyang’, the standard cultivar for WCS rice. Moreover, the growth duration of ‘Jonong’ is the shortest among all Korean WCS rice cultivars. The culm length of ‘Jonong’ is 88 cm, which 4 cm longer than that of ‘Nokyang’ and the highest among all Korean early maturing rice cultivars. ‘Jonong’ has 149 spikelets per panicle, which is 30 more than that of ‘Nokyang’, and is the highest among all Korean early maturing rice cultivars. ‘Jonong’ exhibits stable premature heading and is tolerant to lodging. It is moderately resistant to leaf blast and resistant to the rice stripe virus. The feed value of ‘Jonong’ in terms of total digestible nutrients is good and comparable to that of ‘Nokyang’. Furthermore, compared with ‘Nokyang’, ‘Jonong’ shows a similar level of dry matter yield and a higher rough rice yield. Therefore, ‘Jonong’, an early maturing WCS japonica rice with short growth duration and numerous spikelets, would be suitable for cultivating in winter forage crop-rice double cropping systems (Registration No. 7274).

Rice is the most important staple food in Korea. Rice blast, caused by Magnaporthe oryzae, is one of the most devastating diseases in the rice-growing world and in Korea. Eighteen major blast resistance genes were screened in 33 leading Korean japonica varieties using 44 DNA markers. The 33 leading japonica varieties are cultivated in 659,642 ha (90.4%), and a variety of Samkwang is cultivated widely on a nation-wide scale. Four resistance genes, Pia, Pib, Pi19, and Pb1, were detected in 10-21 varieties, and the R-genes of Pii, Pish, Pita/Pita-2, Piz/Piz-t, Pi35, and Pi65(t), were present in 2-5 varieties. Five R-genes, Pit, Pi5, Pi9, pi21, and Pi40, were not detected in the Korean japonica rice varieties. A total of six varieties, two mid-late flowering varieties, Ilmi and Saeilmi, a medium flowering variety Gopum; and three early flowering varieties Jopyeong, Haedamssal, and Haedeul; were resistant to blast nursery screening over 12 years. A variety of Gopum harbored alleles for Piz/Piz-t, and three early flowering varieties, Jopyeong, Haedamssal, and Haedeul, had extensive loci of the multiple-gene family Piz/Piz-t, Pi9, and Pi40 on chromosome 6. Two mid-late flowering varieties, Ilmi and Saeilmi, harbored the Pita-2 gene, and Gopum had Pita. In the japonica rice breeding program, an effective means for enhancing stable resistance to blast would be introduced to 2-3 R genes among resistance genes Pit, Pi5, Pi9, pi21 and Pi40 which were not identified in Korean japonica rice varieties, and resistance genes Pita/Pita-2, Piz-t/Piz-5, to 2-3 R genes among and Pi20 that showed stable resistance in monogenic IRBL lines.

‘Jungmo1022’, a japonica rice cultivar, was developed by a cross between ‘Jinbu31’ (IT212616) and ‘Gyodong23’ (IT213764) by the rice breeding team at the National Institute of Crop Science, Korea, in 2000. ‘Jinbu31’ is tolerant to cold, and ‘Gyodong23’ is early maturing with high yield potential. The growth period of ‘Jungmo1022’ in paddy fields was 116 days on the North-middle highland in Korea, shorter than that of ‘Jinbu’. The culm length of ‘Jungmo1022’ was 67 cm, which was 2 cm shorter than that of ‘Jinbu’. There were 91 spikelets per panicle in ‘Jungmo1022’. The elite line was developed by shuttle breeding in a cold screening field at Chuncheon and highland Jinbu sites in order to screen for cold tolerant varieties. Forty-five lines with more than 50% fertility were selected from the F₂ generation in the cold screening field, and the line SR28990-B-2-2-2 was selected by the pedigree breeding method through F₃-F₇ generations cultivated on the North-middle highland in Jinbu. During the yield trial conducted in 2008-2009 yield trial, an early heading, high-yielding, and cold tolerant line ‘Jinbu 48’ was selected for the local adaptability tests conducted from 2010 to 2012. The early maturing and cold-tolerant ‘Jinbu 48’ was superior to ‘Jinbu’ in exhibiting shorter heading delay, reduced culm length, and spikelet fertility under cold temperature. The new line showed a milled rice productivity of 5.69 MT/ha at Jinbu sites under North-middle highland cultivation and was registered as a new cultivar ‘Jungmo1022’ (Registration No. 5563).

‘Cheongwoo’, a late maturing, high biomass-yielding rice (Oryza sativa L.) cultivar with high feed value and multiple disease and insect resistance, was developed for whole crop silage (WCS) use. It was derived from a cross between a high biomass and multiple disease resistant line ‘Suweon519’ and early flowering, high-yielding Tong-il type cultivar ‘Gaya’, which exhibited a brown planthopper (BPH) broad resistance conferred by Bph3 and BPH26. The cultivar was characterized by growth period from seeding to heading of about 130 days, culm length of 87 cm, panicle length of 29 cm, 12 panicles per hill, 135 spikelets per panicle, and 1,000-grain weight of brown rice of 21.4 g in the central plain region, Suwon. This long-leaved green WCS rice variety was sensitive to cold stress, similar to ‘Nokyang’, but resistant to premature germination, and germinated well under low temperature conditions. Furthermore, ‘Cheongwoo’ exhibited high lodging resistance at the yellowing stage, the optimal period for harvesting in the field. Additionally, ‘Cheongwoo’ was resistant to leaf and neck blast, bacterial blight (races K1, K2, K3, K3a), rice stripe virus, BPH, and small BPH. Its average dry matter yield for three years reached 20.6 MT/ha, 38% higher than that of ‘Nokyang’. The content of crude protein (5.32%) and total digestible nutrients (71.2%) was higher than that in ‘Nokyang’. On the Korean Peninsula, ‘Cheongwoo’ grows well in central and southern plains, and should be optimally harvested between 15 and 30 days after heading to improve its feeding value and digestion rate in livestock (Grant No. 7662).

‘Yechan’ is a high grain quality mid-late maturing rice cultivar with lodging tolerance and multiple disease resistance. It was a derived from a cross between ‘Hopum’ and ‘Iksan537’ (cultivar name ‘Haepum’). ‘Hopum’ is a high grain quality mid-late maturing rice cultivar with strong lodging tolerance and ‘Haepum’ is a high grain quality medium maturing rice cultivar with multiple disease resistance. To shorten the breeding period, another culture method was applied to the F₁ plants. ‘Yechan’ was selected through the pedigree method, yield trials, and local adaptability tests, with a high selection pressure for grain quality, lodging, and disease resistance. The heading date of ‘Yechan’ was August 14, one day later than that of ‘Nampyeong’. ‘Yechan’ is a cultivar tolerant to lodging and it has short culms. It has multiple disease resistance against rice blast, rice stripe virus, and bacterial blight, including the K3a race, the most virulent race in Korea. The yield of ‘Yechan’ was similar to that of ‘Nampyeong’. ‘Yechan’ showed excellent grain appearance, superior taste when cooked, and enhanced milling performance; thus, we concluded that it could contribute to the improvement of Korean japonica rice cultivar quality. ‘Yechan’, a high grain quality mid-late maturing rice cultivar with lodging tolerance and multiple disease resistance, would be suitable for cultivation in the southern plain area in Korea and has been utilized in the breeding programs aimed at enhancing the grain quality and stability for the cultivation of Korean japonica rice (Registration No. 7647).

‘Jinhan’, a japonica rice variety, was developed from a cross between ‘Cheolwon68’ (IT218244) and ‘Junghwabyeo’ (IT260473) by the rice breeding team at National Institute of Crop Science in 2015. ‘Cheolwon68’ is early maturing and resistant to blast disease, and ‘Junghwabyeo’ is a cold-tolerant and high-quality variety. The growth duration of ‘Jinhan’ in the paddy field was 116 days in the Northern Central Highland in Korea, which was similar to that of ‘Jinbu’. The culm length of ‘Jinhan’ was 61 cm, which was 10 cm shorter than that of ‘Jinbu’. The panicle of ‘Jinhan’ was composed of 66 spikelets. The viviparous germination rate of ‘Jinhan’ was 33.2%. ‘Jinhan’ showed resistance to blast disease, but was susceptible to stripe virus, dwarf and black-streaked dwarf viruses, and plant hoppers. The milled rice grains of ‘Jinhan’ showed an excellent palatability index (0.23) and lower protein content (5.7%) than that of ‘Jinbu’. The grain milling characteristics of ‘Jinhan’ were similar to those of ‘Jinbu’. ‘Jinhan’ showed a milled rice productivity of 5.43 MT/ha at four sites cultivated in the Northern Central Highland (Registration No. 7318).

Hypoxia caused by water seeding of rice inhibits germination and often leads to serious problems in seedling establishment and early growth. To solve this problem, it is necessary to develop rice cultivars that can stably germinate and grow under anaerobic environments. In this study, we performed QTL analysis on anaerobic germination (AG) tolerance using 139 recombinant inbred lines (RILs) derived from a cross between Milyang23 and Gihobyeo, and identified two QTLs (qAG2.1, qAG2.2) on chromosome 2. The LOD scores at qAG2.1 and qAG2.2 were 3.30 and 5.31, respectively. The phenotypic variances explained by the QTLs were 9.19% and 14.99%, respectively. The japonica cultivar Gihobyeo provided alleles for AG tolerance at both QTLs. While the chromosomal location of qAG2.2 overlapped with previously identified QTLs for AG tolerance, qAG2.1 was detected in a locus that has not been reported previously. The RILs carrying favorable type alleles for the AG tolerance at both QTLs (qAG2.1 + qAG2.2) expressed 41.0% survival rate under the AG condition, which was significantly higher than those of the RILs carrying single QTL, qAG2.1 (22.0%) or qAG2.2 (26.2%). As the favorable alleles for the two QTLs found in this study derived from the japonica cultivar Gihobyeo, it is expected that they would accompany less linkage drag such as shattering and lodging compared to those derived from indica or landraces. The result of this study would provide useful information for improving AG tolerance of japonica rice cultivars that can be used for water seeding cultivation.

Rice blast caused by the fungus Magnaporthe grisea (anamorphic: Pyricularia oryzae) is an important disease in rice and development of resistant varieties to blast is one of the most important goals in rice breeding programs. A japonica rice variety, Palgong, has shown resistance to the Korean blast pathogen since it was developed in 1996. Nine blast resistance quantitative trait loci (QTLs) in Palgong alleles were identified on chromosomes 2, 4, 7, and 11. Four QTLs of qBn2.3, qBn4.2, qBn11.1, and qBn11.2 explained 28–56.7% of total phenotypic variation, while five QTLs of qBn2.2, qBn2.4, qBn4.1, qBn7.1, and qBn7.2 explained 9.7–18.8%. In a previous study, one to four resistance genes were located on the loci qBn2.2, qBn2.3, qBn4.2, qBn11.1, and qBn11.2, however, resistance genes were not located on the loci qBn2.4, qBn4.1, and qBn7.1. A major QTL, qBn11.2, explaining 56.7% of total phenotypic variation was related to the durable resistance of Palgong. Additionally, rice stripe virus resistance of Palgong was assumed to be based on the Stvb-i gene, which is located on a major QTL qBn11.2.

‘Sinjinbaek’ is a bacterial blight (BB)-resistant, mid-late maturing rice cultivar with high grain quality. To diversify the resistance genes and enhance the resistance of Korean rice cultivars against BB, ‘Sinjinbaek’ was developed from a cross between ‘Iksan493’ (cultivar name ‘Jinbaek’) and the F₁ cross between ‘Hopum’ and ‘HR24670-9-2-1’ (‘HR24670’). ‘Jinbaek’ is a BB-resistant cultivar with two BB resistance genes, Xa3 and xa5. ‘Hopum’ is a high grain quality cultivar with the Xa3 resistance gene. ‘HR24670’ is a near-isogenic line that carries the Xa21 gene, a resistance gene inherited from a wild rice species O. longistaminata, in the genetic background of japonica elite rice line ‘Suweon345’. ‘Sinjinbaek’ was selected through the pedigree method, yield trials, and local adaptability tests. Using bioassay for BB races and DNA markers for resistance genes, three resistance genes, Xa3, xa5, and Xa21, were pyramided in the ‘Sinjinbaek’ cultivar. ‘Sinjinbaek’ exhibited high-level and broad-spectrum resistance against BB, including the K3a race, the most virulent race in Korea. ‘Sinjinbaek’ is a mid-late maturing rice cultivar tolerant to lodging. It has multiple disease resistance against BB, rice blast, and stripe virus. The yield of ‘Sinjinbaek’ was similar to that of ‘Nampyeong’. ‘Sinjinbaek’ showed excellent grain appearance, good taste of cooked rice, and enhanced milling performance, and we concluded that it could contribute to improving the quality of BB-resistant cultivars. ‘Sinjinbaek’ was successfully introgressed with the Xa21 gene without the linkage drag negatively affecting its agronomic characteristics. ‘Sinjinbaek’ improved the resistance of Korean rice cultivars against BB by introgression of a new resistance gene, Xa21, as well as by pyramiding three resistance genes, Xa3, xa5, and Xa21. ‘Sinjinbaek’ would be suitable for the cultivation in BB-prone areas since it has been used in breeding programs for enhancing plants’ resistance to BB (Registration No. 7273).

‘Bodrami’ is a brown rice cultivar suitable for cooking, developed by crossing ‘Hwaseong’ and ‘Congsengla’ cultivars at Rural Development Administration, Korea, in 2003. Cooked brown rice of ‘Bodrami’ naturally has a soft texture, and after 24 hours of warm treatment, it maintained its soft texture and it was evaluated that the taste and texture of cooked brown rice were better than that of another rice cultivar. ‘Bodrami’ is a mid-maturing rice cultivar. The average heading date in ordinary planting was August 11^th in Suwon, Korea, which also exhibits strong to blast leaf and rice stripe virus, and brown rice yield of ‘Bodrami’ had a yield of 5.56 MT/ha in ordinary planting. The advantages of eating brown rice are high intake of GABA (which is excellent for controlling blood), γ-oryzanol (which is good for Antioxidation), rice embryos (rich in fiber), and rice bran (rich in minerals). Another advantage of ‘Bodrami’ is that, compared to glutinous rice varieties (which is a higher glycemic index), it has a lower glycemic index and a smooth texture. The consumption of white rice has been decreasing recently, while interest in brown rice has been increasing as a consequence of these advantages. ‘Bodrami’ was developed in response to recent changes in consumption preferences. (Registration No. 5644)

‘Baegilmi’ is an extremely early maturing rice variety that can be harvested within 100 days after transplanting, and also exhibits strong blast resistance and good grain appearance. From a mutant population of ‘Koshihikari’ treated with ethyl methanesulfonate, a promising line, ‘Suweon 559’, was selected through pedigree breeding and yield trials, and subsequently registered as ‘Baegilmi’. According to the 3-year (2012–2014) regional adaptability tests, the average heading date of Baegilmi in ordinary planting was July 14^th, which was 23 and 9 days earlier than that of the check varieties ‘Hwaseong’ and ‘Odae’, respectively. The milled rice yield of ‘Baegilmi’ was 4.53 MT/ha in ordinary planting (83% and 98% of ‘Hwaseong’ and ‘Odae’, respectively). ‘Baegilmi’ had a culm length of 75 cm (10 cm shorter than ‘Hwaseong’), a panicle length of 21 cm (similar to ‘Hwaseong’), and 12 panicles per plant (two fewer than ‘Hwaseong’). The brown rice of ‘Baegilmi’ was slightly more slender than ‘Hwaseong’, with a 1,000 grain weight of 20.6 g and length/width ratio of 1.92. The milled rice of ‘Baegilmi’ was translucent, with a protein content of 8.4% (1.7% higher than ‘Hwaseong’) and an amylose content of 18.6% (similar to ‘Hwaseong’). ‘Baegilmi’ exhibited strong blast resistance, but was susceptible to bacterial blight, viral diseases, and insect pests. The release of ‘Baegilmi’ is expected to provide a useful early-maturing rice variety that can be used in diverse cropping systems in paddy fields (Registration No. 6805).

“Hyangcheola” is a new japonica rice variety developed as a cross between “Joryeong” and “Seolhyangchal” by the rice breeding team at NICS in 2014. The heading date of “Hyangcheola” is July 28 in the middle plain area, which is 8 days earlier than that of “Hwaseong.” “Hyangcheola” has a 76 cm long culm, which is 8 cm shorter than “Hwaseong” and has 86 spikelets per panicle. The viviparous germination rate of “Hyangcheola” was 27.9%. It showed resistance to stripe virus but susceptibility to bacterial blight (K1, K2, and K3 races), dwarf and black streak dwarf viruses and planthoppers. The milled rice of this variety exhibits translucent and medium short grain shape. The protein content of “Hyangcheola” was 8.2%, which was 1.5% higher than that of “Hwaseong.” “Hyangcheola” is a rice with a fragrant aroma. The content of iron in 100 g of brown “Hyangcheola” rice was 15.12 mg, which is 3.69 mg higher than that of “Hwaseong,” and the zinc content was 32.24 mg, which is 8.75 mg more than that of the comparative variety “Hwaseong.” The average milled rice yield of “Hyangcheola” was 4.8 MT/ha at our sites under ordinary cultivation (Registration No. 6807).

‘Yeongwoo’, a mid-late flowering, high dry matter yielding rice (Oryza sativa L.) cultivar with high feed value and multiple disease-insect resistance, was developed for whole crop silage (WCS) use. It was derived from a cross between a high biomass and brown planthopper (Bph) resistant ‘SR25848-C99-1-2-1’ and high yielding Tong-il type, ‘Yongmun’ which had diseases resistance. This cultivar had about 117 days growth period from seeding to heading, 99 cm culm length, 26 cm panicle length, 11 panicles per hill, 125 spikelets per panicle, and 1,000-grain weight of 23.6 g as brown rice in the central plain region, Suwon. This wide and long leafy WCS rice variety was weak to cold stresses, similarly to ‘Nokyang’ but was resistant to lodging in the field, strong to viviparous germination, and good under low temperature germination. In addition, ‘Yeongwoo’ was resistant to leaf and neck blast, bacterial blight (race K1, K2, K3, K3a), rice stripe virus, Bph, and small Bph. Its average dry matter yield for three years reached 20.0 MT/ha, 32% higher than that of ‘Nokyang’. This cultivar had 5.3% crude protein and 71.7% total digestible nutrients, which was slightly lower than that of ‘Nokyang’. In the Korean peninsula, ‘Yeongwoo’ grew well in the central and southern plain and was could be harvested between 15 to 30 days after heading to improve the feeding value and digestion rate of livestock (Grant No. 6800).

Joil’ is a multiple disease resistant early maturing rice cultivar with high grain quality. ‘Joil’ was derived from a single cross between ‘Unbong37’ (cultivar name ‘Unmi’) and ‘HR23156-26-2-3-5’. ‘Unmi’ is an early maturing rice cultivar with high grain quality and resistance to rice blast and stripe virus. ‘HR23156-26-2-3-5’ is an early maturing elite rice line with lodging resistance and cold tolerance. ‘Joil’ was selected through the pedigree method, yield trials, and local adaptability tests. ‘Joil’ was an early maturing rice. The heading date of ‘Joil’ was July 16 in early transplanting cultivation, which was 2 days later than that of ‘Jopyeong’. ‘Joil’ was a lodging resistance rice with a short culm and showed better tolerance to viviparous germination than that of ‘Jopyeong’. ‘Joil’ was a multiple disease resistant rice with resistance against rice blast, bacterial blight, and stripe virus. ‘Joil’ showed higher yield in both early and late-transplanting cultivations than those of the standard rice cultivars ‘Jopyeong’ and ‘Geumo’. ‘Joil’ had enhanced grain quality under high temperature ripening conditions in early transplanting cultivation. The cooked rice had good grain appearance and taste attributes, and this cultivar had a higher head rice ratio than that of ‘Jopyeong’. ‘Joil’, a multiple disease resistant early maturing rice cultivar with high grain quality, would be suitable for early transplanting cultivation in the southern plain area (Registration No. 6792).

The ‘Seonpum’ is a rice variety derived from a cross between ‘Junam’ which has translucent milled rice and mid-late maturity and ‘Iksan457’ that the elite line has a bacterial blight resistance and medium maturing property by the rice breeding team at NICS, RDA in 2003. The heading date of ‘Seonpum’ is August 11 and four days later than check variety, ‘Hwaseong’. It has 84 cm of culm length and 124 spikelets per panicle. This variety showed similar cold tolerance to ‘Hwaseong’ while exposed to cold stress. ‘Seonpum’ showed resistance to blast disease, stripe virus and K1, K2 and K3 race of bacterial blight, but susceptible to K3a race, other viruses and planthoppers. The milled rice of this variety exhibits translucent, clear non-glutinous endosperm and short grain shape. It has similar protein content (6.7%) and amylose content (19.4%) to that of ‘Hwaseong’. ‘Seonpum’ showed better palatability index of cooked rice than that of ‘Hwaseong’. Its milled rice recovery rate is similar to those of ‘Hwaseong’. However, whole grain rate of milled rice is higher than that of ‘Hwaseong’. ‘Seonpum’ has 5.74 MT/ha of milled rice productivity in ordinary cultivation. ‘Seonpum’ could be adaptable to the middle plain area in Korea. (Registration No.6810).

To diversify the grain size and shape of japonica rice, we developed the Breeding Materials with Diverse Grain Size and Shape (BM_DGS) and characterized the grain and yield-related traits. We used the donor parents Jizi1560 and Jizi1581, japonica germplasm with extremely large grain size. Four cross combinations between the each donor parents and Korean high yielding japonica rice cultivars, Deuraechan and Boramchan, were constructed and anther culture method was applied. Among 290 doubled haploid lines, we selected 91 elite lines with diverse grain size and shape and designated to the BM_DGS. The grain size and shape of BM_DGS exhibited beyond the characteristics of previously developed Korean rice cultivars. The alleles of major grain-related genes, GW2, GS3, and qSW5, in BM_DGS showed two types, wild type or loss-of-function mutant type. The loss-of-function mutant alleles, gw2, gs3, and qSw5, had an effect on increasing grain size. The phenotypic variation of grain length was mostly controlled by GS3 alleles, and grain width and thickness were influenced by the combinations of GW2 and qSW5 alleles. 1,000-grain weight was determined by the combinations of GW2, GS3, and qSW5. The grain-related genes influenced the phenotypic variation of yield-related traits. The result of this study could be useful to elucidate the relationship between the grain-related genes and agronomic traits. And the BM_DGS are being utilized in the breeding programs to diversify the grain size and shape in japonica rice.

‘Nokwoo’, a mid-late maturing, high dry matter yielding rice (Oryza sativa L.) cultivar with a good early growth and low-temperature germinability, was developed for whole crop silage (WCS) use. It was derived from a cross between a leafy tropical japonica ‘LK1A-2-12-1-1’ with high biomass and good germinability in low temperature and new plant type (NPT), ‘IR72225-29-1-1’ which had low tillering trait, large panicle, dark green leaf, thick and sturdy stem and vigorous root system. This cultivar had about 123 days growth period from seeding to heading, 122㎝ culm length, 29㎝ panicle length, 9 panicles per hill, 144 spikelets per panicle and 1,000-grain weight of 24.4 g as brown rice in central plain region, Suwon. This wide and long leafy WCS rice variety was weak to cold stresses similar to ‘Nokyang’ but was a little resistant to lodging in the field, strong to viviparous germination and good to low temperature germination. In addition, ‘Nokwoo’ was resistant to leaf and neck blast but susceptible to bacterial blight, rice stripe virus and brown planthopper. Its average dry matter yield for three years reached 16.5 MT/ha, 14% higher than that of ‘Nokyang’. This cultivar had 5.3% crude protein and 68.8% total digestible nutrients a little low compared to ‘Nokyang’. In Korea peninsular, ‘Nokwoo’ grows well in central and southern plain and is good to harvest between 15 to 30 days after heading to improve its feeding value and digestion rate of livestock (Grant No. 6072).

‘Jungmo1038', a mid-late maturing, high dry matter yielding rice (Oryza sativa L.) cultivar with glabrous leaf and hull, was developed for whole crop silage (WCS) use. It was derived from a cross between ‘SR24592-HB2319’ with high biomass, smooth leaf and hull and good germinability in low temperature and new plant type (NPT), ‘IR73165-B-6-1-1‘ which had low tillering trait, large panicle, dark green leaf, thick and sturdy stem and vigorous root system. This cultivar had about 125 days growth period from seeding to heading, 99cm culm length, 20cm panicle length, 13 panicles per hill, 119 spikelets per panicle and 1,000-grain weight of 23.3 g as brown rice in central plain region, Suwon. This hairless WCS rice variety was weak to cold stresses similar to ‘Nokyang’ but was resistant to lodging in the field, strong to viviparous germination and good to low temperature germination. In addition, ‘Jungmo1038’ was resistant to leaf and neck blast but susceptible to bacterial blight, rice stripe virus and brown planthopper. Its average dry matter yield for three years reached 17.2 MT/ha, 21% higher than that of ‘Nokyang’. This glabrous cultivar had 6.6% crude protein and 62.4% total digestible nutrients a little low compared to ‘Nokyang’. In Korea peninsular, 'Jungmo1038' grows well in central and southern plain and is good to harvest between 15 to 30 days after heading to improve its feeding value and digestion rate of livestock(Grant No. 5634).

‘Jungmo1024’ is a blast resistant early maturing rice cultivar with high temperature tolerance during grain filling stage. ‘Jungmo1024’ was derived from a sodium azide treatment on ‘Suweon472’, a high yielding japonica elite line which was latterly registered as ‘Namil’. Comparison with the agronomical traits of ‘Namil’, ‘Jungmo1024’ was uniquely characterized as the induced gained function due to the reduced culm length, increased tiller number, strong blast resistance and especially high temperature tolerance during grain filling stage. The high temperature tolerance of ‘Jungmo1024’ was supported by two years experiments by comparing the head rice ratio produced in ordinary paddy field and green house condition. The heading date of ‘Jungmo1024’ was July 29 in central plain area, which was 9 days earlier than that of ‘Hwaseong’. The milled rice yield performance of ‘Jungmo1024’ was about 4.98 MT/ha in local adaptability test for three years. ‘Jungmo1024’ had 69 cm in culm length, which was 15 cm shorter than that of ‘Hwaseong’, 20 cm in panicle length, 16 in tiller number, and 22.3g in 1,000 grain-weight of brown rice. ‘Jungmo1024’ exhibited strong rice blast resistance, but do not have any clear resistance gene sources against bacterial blight, viral diseases and insect fests. ‘Jungmo1024’, nevertheless, would be a useful rice cultivar could be used as a donor line for the breeding programs for developing southern plane adaptable early maturing rice cultivars with enhanced rice blast resistance, lodging tolerance, and especially high temperature tolerance during grain filling stage.

A doubled haploid (DH) lines derived from the cross between high-yielding japonica rice cultivars ‘Deuraechan’ and ‘Boramchan’ was developed to increase diversity of panicle and yield-related traits and select high-yielding lines. Panicle and yield-related traits of DH population consisting of 163 lines and 13 selected high-yielding lines were analyzed using correlation, principal component, and path analysis. Among panicle-related traits, number of spikelets on secondary rachis-branches (SRBs) was more highly correlated with and had more positive effect on number of spikelets (NS) than number of spikelets on primary rachis-branches (PRBs) per panicle. In the DH population, NS had the most positive effect on yield, whereas panicle number per hill (PN) was in the selected lines. PN was significantly positive correlated with ratio of ripened grain (RGG) in both case. The enhancement of ripening and increase of total spikelets number by increasing PN had more effect on yield than increase of total spiekelts number by increasing NS in the selected lines. Among 13 lines, four lines, AC60, AC152, AC156, and AC161 showed higher yield than Deuraechan (481 kg/10a) and Boramchan (558 kg/10a). Deuraechan exhibited panicle-weight type with low tiller and heavy panicles and Boramchan was slightly panicle-number type with more PN and higher RGG. Selected high-yielding lines showed medium characteristics of parents with improved yield potential. These elite lines could be utilized to develop high-yielding japonica rice.

‘Jungmo1029’, a late-maturing, high biomass and multiple disease resistant rice (Oryza sativa L.) cultivar, was developed for whole crop silage (WCS) use. It was derived from a cross between ‘Gillim collection1’ with high biomass and ‘Junam’ which has some of diseases resistant genes. This elite cultivar had about 127 days growth period from seeding to heading, 105 cm culm length, 11 panicles per hill, 163 spikelets per panicle and 1,000-grain weight of 21.5 g as brown rice. This WCS rice variety was weak to cold stresses similar to ‘Nokyang’ but was tolerant to lodging in the field. In addition, ‘Jungmo1029’ was resistant to leaf and neck blast, bacterial blight except race K3a and rice stripe virus but susceptible to brown planthopper. Its average dry matter yield for three years reached 17.1 MT/ha, 14% higher than that of ‘Nokyang’. This stay green cultivar had good quality for WCS with low acid detergent fiber and high total digestible nutrients similar to ‘Nokyang’. ‘Jungmo1029’ was suitable for cultivation in the central and southern plain area of the South Korean peninsula and required to harvest 15~30 days after heading to improve the digestibility of cattle (Registration No. 5104).

There are farmer’s demands to develop early-maturing cultivar in order to replace Odae variety to mid-northern inland plain and southern mountainous area of Korea. Saeodae was developed by the rice breeding team of Cheolwon Substation, National Institute of Crop Science (NICS), RDA in 2012. This cultivar was derived from the cross between Geuroobyeo and Suweon 472 in 2001 summer season, and selected by a promising line, SR27376-2-2-1-3, was selected and designated as the line of Cheolweon 81 in 2010. The local adaptability test of Cheolweon 81 was carried out at four locations from 2010 to 2012 and it was named as Saeodae. The heading date of Saeodae is July 25 in Cheolwon area, which is 2 days earlier than that of Odae. This variety has 66cm in culm length and 77 spikelets per panicle. Its 1,000 grain-weight of brown rice is 26.5 g, which is similar to that of Odae. Germination rate at low temperature of this variety is about 70%, and viviparous germination is 17.7%. Cold tolerance of this cultivar is still not good, just mediocre. It shows strong lodging resistance. And premature heading, occurrence of wilting during ripening stage, and leaf senescence at maturing are similar to those of Odae. This variety shows resistance to leaf blast disease, but susceptible to bacterial blight, virus disease and insect pest. This variety has translucent and clear milled rice kernel without white core and belly rice. The yield potential of Saeodae was about 5.26 MT/ha at ordinary fertilizer level in local adaptability test for three years. This variety would be adaptable to mid-northern inland plain and southern mountainous area of Korea.

The ‘Jungmo1017’ is a japonica rice variety developed from a cross between Suweon462 which has a good plant architecture, cold tolerance, moderately tolerant to leaf blast and bacterial blight and medium maturing habit, and Yeongdeog34 which has translucent milled rice and good milling properties, by the rice breeding team at NICS, RDA in 2011. The heading date of ‘Jungmo1017’ is August 16 and it is six days later than ‘Hwaseong’. ‘Jungmo1017’ has 65 cm of culm length which is 18 cm shorter than those of ‘Hwaseong’ and 93 spikelet per panicle. The pre-harvest sprouting rate of ‘Jungmo1017’ is 8.6% that is lower than 27.7% of ‘Hwaseong’ on local adaptability test (LAT). It showed resistance to blast diseases and moderately resistant to bacterial blight (K1 race) and stripe virus, but susceptible to other races (K2, K3 and K3a) of bacterial blight, viruses and planthoppers. The milled rice of this variety exhibits translucent, clear non-glutinous endosperm and medium short grain shape. It has better palatability index of cooked rice (0.53) than that of ‘Hwaseong’. ‘Jungmo1017’ showed lower protein content (6.4%) and amylose content (18.0%). ‘Jungmo1017’ could use aseptic-packaged cooked rice or processing cooked rice because its hardness of cooked rice is soft, setback and balance is low and palatability of cold and aseptic rice showed high score. The characters related to milling is better than those of ‘Hwaseong’. ‘Jungmo1017’ showed 5.01 MT/ha of milled rice productivity at 7 sites of middle plain, southern mid-mountainous and south-east coastal area in ordinary cultivation. ‘Jungmo1017’ could be adaptable to the middle plain area in Korea.

Sheonhyangheukmi, black pericarp and aromatic rice (Oryza sativa L.) variety, was developed by the rice breeding team of National Institute of Crop Science (NICS), RDA in 2011. This variety was derived from the cross between Suweon477 and CG2-2-75-4-1-22-3 in 2002 summer season, and selected by a promising line, SR28684-9-2-2-2, was selected and designated as the line of Suweon532 in 2009. The local adaptability test of Suweon532 was carried out from 2009 to 2011 and it was named as Sheonhyangheukmi in 2011. This variety is medium matured with heading date of August 11 in central plain area of Korea. This variety is about 89 cm tall culm length and 122 spikelets per panicle. Its 1,000 grain-weight of brown rice is 17.0 g. This variety is susceptible to leaf blast and and insect pest, but resistant to bacterial leaf blight and moderately resistant to stripe virus disease. This variety has tolerance to unfavorable environment such as cold. Milled rice of Sheonhyanghuekmi is non-glutinous and aromatic endorsperm. This variety has higher anthocyanin content compared to black pigmented variety Heukjinju. The yield potential of Sheonhyangheukmi in brown rice was about 4.75 MT/ha at ordinary fertilizer level in local adaptability test for three years. This variety would be adaptable to the southern plain and middle plain of Korea.

Geonyangmi, low glutelins rice cultivar, was developed by the rice breeding team of National Institute of Crop Science (NICS), RDA in 2011. This cultivar was derived from the cross between Jinmi TR and LGC-1 in 2003 summer season, and selected by a promising line, SR29355-B-51-2-2-1, was selected and designated as the line of Suweon533 in 2009. The local adaptability test of Suweon533 was carried out at three locations from 2009 to 2011 and it was named as Geonyangmi. This variety is a mid-late maturity cultivar. This variety has 90 cm in culm length and 124 spikelets per panicle. Its 1,000 grain-weight of brown rice is 19.3 g which is less than that of Hwaseonbyeo. This variety has tolerance to unfavorable environment such as cold. This variety has translucent and clear milled rice kernel without white core and belly rice. It has low glutelin content compared with Jinmibyeo. This variety is susceptible to leaf blast, bacterial blight, virus disease and insect pest. The yield potential of Geonyangmi was about 4.93 MT/ha at ordinary fertilizer level in local adaptability test for three years. This variety would be adaptable to the plain paddy field of middle of Korea.