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).

The cultivation of early maturing rice in the plain areas in Korea is increasingly diversifying its cropping systems. Early maturing rice cultivars are usually vulnerable to bacterial blight (BB) and rice stripe virus (RSV) compared to mid- and mid-late maturing rice cultivars. To enhance the resistance of early maturing rice against BB and RSV, ‘IS592BB’ was developed by introgression of resistance genes, Xa3, Xa21, and Stvb-i into the genetic background of ‘Unkwang’, an early maturing rice cultivar with excellent agronomic characteristics. ‘IS592BB’ was derived from a backcross between ‘Unkwang’ and the F1 cross between ‘Unkwang’ and ‘SR31206-12’ (‘Unkwang’/‘SR30075’) and selected through the pedigree method, yield trials, and local adaptability tests. Using bioassay and marker-assisted selection to BB and RSV, Xa3, Xa21, and Stvb-i were pyramided in ‘IS592BB’. ‘IS592BB’ exhibited high-level and broad-spectrum resistance against BB, including the K3a race, the most virulent race in Korea, and also showed a resistance reaction to RSV. ‘IS592BB’ was found to be an early maturing rice cultivar with similar agronomic characteristics to ‘Unkwang’ such as early maturing, lodging tolerance with short culm, erect plant architecture, blast resistance, and high-yielding performance. In the genetic background analysis using 771 KASP (Kompetitive Allele-Specific PCR) markers, ‘IS592BB’ was confirmed to be the near-isogenic line (NIL) of ‘Unkwang’ with a 93.6% recovery rate. ‘IS592BB’ was successfully introgressed with the Xa3+Xa21+Stvb-i genes into ‘Unkwang’ without linkage drag negatively affecting its agronomic characteristics. ‘IS592BB’ would enhance the adaptability of early maturing rice in the plain area through its multiple disease resistance (Registration No. 7648).

The cultivation of early maturing rice in the Honam plain area of Korea is increasing to diversify the cropping systems. The cropping systems of this rice are usually classified as early, ordinary, and late cultivations based on transplanting time. The characteristics of varieties vary depending on the cultivations. To evaluate the performance of varieties and interpret the relationships between genotype and environment, nine yield and 17 panicle-related traits of six early maturing rice varieties (Jopyeong, Odae, Unkwang, Haedamssal, Jinkwang, and Haedeul) were characterized on early, ordinary, and late cultivations. Heading date was longer in order of early, ordinary, and late cultivations. The cumulative mean temperature of growth stage was similar for all cultivations. The variation in the number of spikelets per panicle (NS) was mainly due to the variety and the traits related with secondary rachis-branch were affected more by variety than the traits related to primary rachis-branch. The varieties with the highest yield were Haedamssal on early maturing cultivation and Unkwang on ordinary and late cultivations. Haedamssal displayed a panicle-number type plant architecture with relatively higher number of panicles per hill (PN) and average NS. Unkwang exhibited panicle-weight type with many NS and less PN. Additive main effects and multiplicative interaction analysis revealed that, NS and HD were mostly affected by genotype and environment, respectively. Among yield-related traits, NS contributed the most to enhanced yield of varieties in all cultivations. NS could be the target trait of breeding programs intended to improve the yield potential of early maturing rice adaptable to the Honam plain area. However, proper PN should be considered because PN, which was negatively correlated with NS, also affected the yield.

‘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).

‘Seongsan’, an early multi-resistant japonica rice cultivar developed from a cross between ‘Jopyeong’ and ‘Jungmo 1012’, was developed by the rice breeding team of the National Institute of Crop Science, Rural Development Administration. The average heading date at the ordinary planting was July 25th in seven test spots. In response to physiological stresses, premature heading rate was very low and viviparous germination rate was relatively low (15.7%). In response to biotic stresses, ‘Seongsan’ showed resistance to bacterial blight pathogen K1 to K3, rice stripe virus, and blight leaf. The milled rice of ‘Seongsan’ was translucent with relatively clear non-glutinous endosperm and medium short grain. The cooked rice had good palatability compared with that of ‘Chucheong’. The milled rice yield of this variety was approximately 5.52 MT/ha in a three-year local adaptability test. ‘Seongsan’ was an early maturing multi-resistant rice with good grain quality, and it was expected to be used as a representative for maturity diversification of rice cultivation area (Registration No. 7277).

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)

‘Haepum’ is a bacterial blight-resistant, medium maturing rice cultivar with high grain quality. It was derived from a cross between ‘Iksan493’ (cultivar name ‘Jinbaek’) and the F₁ cross between ‘Iksan495’ (‘Dacheong’) and ‘Iksan496’ (‘Jungmo1005’). Of these three cultivars, ‘Jinbaek’ is a bacterial blight-resistant mid-late maturing rice cultivar with high grain quality, ‘Dacheong’ is a mid-late maturing rice cultivar with multiple resistance to disease and insects, and ‘Jungmo1005’ is a mid-late maturing rice cultivar with lodging tolerance. To develop fixed lines, the anther culture method was applied to F₁ plants. The cultivar ‘Haepum’ was selected using the pedigree method, yield trials, and local adaptability tests. The heading date of ‘Haepum’ was August 11^th, three days earlier than that of ‘Nampyeong’ cultivar. Haepum’ is a cultivar tolerant to lodging and it has short culms. Due to its low rate of viviparous germination, ‘Haepum’ could be useful for preventing pre-harvest sprouting in cultivation of medium maturing rice in the southern plain area of Korea. ‘Haepum’ carries two bacterial blight resistance genes (Xa3 and xa5), and in our study, it exhibited high-level and broad-spectrum resistance against bacterial blight, including K3a, the most virulent race in Korea. ‘Haepum’ is also resistant to the rice stripe virus and moderately resistant to rice blast. The yield of ‘Haepum’ was similar to that of ‘Nampyeong’. ‘Haepum’ showed excellent grain appearance and good taste of cooked rice, and therefore it could contribute to the development of bacterial blight-resistant rice cultivars of improved quality. ‘Haepum’ would be suitable for cultivation in the southern plain area of Korea as well as in bacterial blight-prone areas. (Registration No. 6068)

‘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).

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).

‘Jungmo1045’, a multi-resistant japonica rice cultivar developed from a cross between ‘Hanggeumnuri’ having a good eating-quality and high yield and ‘SR30071’ having brown planthopper (BPH) resistance, was developed by the rice breeding team of NICS, RDA in 2015. This cultivar has about 121 days growth duration from transplanting to harvesting in west-southern coast, Honam and Youngnam plain of Korea. It has 73cm culm length and 22cm panicle length. In reaction to biotic and abiotic stresses, it shows resistance to bacterial blight pathogen races from K1 to K3, stripe virus and brown planthopper. The milled rice of ‘Jungmo1045’ exhibits translucent, relatively clear non-glutinous endosperm and medium short grain. It has good palatability of cooked rice compared with ‘Nampyeongbyeo’. The milled rice yield performance of this variety is about 5.74 MT/ha in local adaptability test for three years. ‘Junngmo1045’ would be useful genetic resources for multi-resistance breeding program against disease and insect and eco-friendly cultivation.

‘Manbaek’ is a bacterial blight resistant mid-late maturing rice cultivar with high grain quality. ‘Manbeak’ was derived from anther culture using the backcross combination, Hopum*2/SR30075. ‘Hopum’ is a mid-late maturing rice cultivar with high grain quality and ‘SR30075’ is a pyramid line carrying three bacterial blight resistance genes. ‘Manbaek’ was selected through the pedigree method, yield trials, and local adaptability tests. ‘Manbeak’ carrying two bacterial blight resistance gene Xa3 and xa5 showed high-level and broad-spectrum resistance against bacterial blight. ‘Manbaek’ was resistant to K3a, mostly virulent race in Korea, and exhibited resistance reaction against 16 Korean bacterial blight isolates. ‘Manbaek’ was a mid-late maturing rice. The heading date of ‘Manbaek’ was August 19th, which was 5 days later than that of ‘Nampyeong’. Manbaek’ was a lodging-tolerant rice with short culm and dark green leaf. Due to the low viviparous germination, ‘Manbaek’ could be a useful material to prevent pre-harvest sprouting. ‘Mabeak’ was resistant to bacterial blight and rice stripe virus, but susceptible to other virus diseases and insect pests. The yield of ‘Manbaek’ was similar to ‘Nampyeong’. ‘Manbaek’ showed excellent grain appearance and good tastes of cooked rice, so that it could contribute to improving the quality of bacterial blight resistant cultivars. ‘Manbaek’, bacterial blight resistant cultivar with high grain quality, is suitable for the cultivation at bacterial blight prone area and has been utilized in the breeding programs for enhancing the resistance against bacterial blight (Registration No. 6069).

Jungmo1019 early maturing rice variety was developed by the rice breeding team of the Department of Southern Crop, NICS, RDA in 2011. This cultivar was derived from the cross Hwayeongbyeo//Hitomebore/Nampyeongbyeo made in 2005 and the production of doubled haploid rice plant from anther culture in F₁ generation. Testing in the replicated yield trial in 2008, a promising line YR25312Acp62 was selected and it was designated as the Milyang246. The early traus plauting local adaptability test of Milyang246 was carried out at three location in 2011 and it was named as Jungmo1019 showing a high head rice ratio and early–maturity eco-type. Number of spikelet/panicle and 1,000 grain weight of brown rice was slightly lower than those of Jopyeongbyeo. This variety is resistant to bacterial blight, rice stripe virus disease but susceptible to major insect and pests. The milled rice yield of Jungmo1019 is 4.52MT per ha at the early transplanting of the local adaptability test. This line should serve as a useful source for improving head rice ratio at early transplanting cultivation in southern plain area.

This experiments were carried out to know the response to Brown Planthopper(BPH) resistance genes at rice seedling stage using Biotype 1 for develoment of resistant cultivars. Varieties with Bph1, Bph3 and Bph18 genes showed a very strong resistance response, BpH2, Bph6, bph7 and Bph9 genes exhibited moderate resistance. Bph5 and Bph8 gene retention varieties and Nampyeongbyeo showed a very weak sensitivity in response to BPH. After 72 hours, Nampyeong(no gene) and IR72(Bph3 gene) were showed a feed-preference 690% and 0%, respectively. Results of Antixenosis and seedling resistance response to BPH were grouped into similar by specific resistance genes. Ten days after inoculation, BPH survival rate of vareities with resistance genes were below 30%, whereas Nampyeongbyeo was more than 70%. The results showed that Bph3 and Bph18 genes are highly resistant response against BPH, these genes are very useful for improve the rice cultivars with various resistance genes

‘Ondami’, a japonica rice cultivar developed from a cross between Hitomebore having a high grain quality and Sangju27 adaptable to southern mid-mountainous area was developed by the rice breeding team of Sangju Substation, NICS, RDA in 2013. The heading date of ‘Ondami’ is july 27 which is same with ‘Odae’ in Southern mid-mountainous area, mid mountainous, southern alpine area and north-east coastal area of South Korea. ‘Ondami’ has 70cm culm length, 19cm panicle length which is 2cm shorter than those of ‘Odae’ and 78 spikelets per panicle. In reaction to biotic and abiotic stresses, it shows strong resistance to blast, but is susceptible to bacterial blight, virus diseases, and insect pests. The milled rice of ‘Ondami’ exhibits translucent and, relatively clear non-glutinous endosperm, and medium short grain shape. This variety has a higher head rice milling recovery ratio(73.1%) and lower amylose content(18.8%) than that of ‘Odae’. The milled rice yield performance of this variety was about 5.29 MT/ha in ordinary cultivation of local adaptability test for three years. ‘Ondami’ could be adaptable to Southern mid-mountainous area, mid mountainous, southern alpine area and north-east coastal area of South Korea.

In chronic renal failure, to reduce the burden on the kidneys, it is necessary to provide patients with therapy based on a low-protein diet. To cope with this situation, low and easy to-digest protein rice variety is helpful. ‘Geongyang2’, low glutelins rice cultivar, was developed by the National Institute of Crop Science (NICS), RDA, Miryang, Korea in 2012. ‘Geongyang2’was derived from a cross between ‘Junambyeo’and‘Chugoku 173’ as a source of low glutelin and amylose. The pedigree of ‘Geongyang2’was YR24174-B-B-B-B-46 and designated as the ‘Milyang262’ in 2009. The local adaptability test of ‘Milyang262’ was carried out at six locations from 2010 to 2012. ‘Geongyang2’ is a mid-maturing ecotype with 65cm in culm length and the number of spikelet/panicle and 1,000 grain weight of brown rice were slightly lower compared to those of ‘Nampyeongbyeo’. ‘Geongyang2’ is resistant to bacterial blight and virus disease while susceptible to major insect and pest. The glutelin and amylose contents of ‘Geongyang2’ were 63.1% and 11.5%, respectively. The milled rice yield of ‘Gyeongyang2’ is 4.61MT/ha at the ordinary transplanting of the local adaptability test. This cultivar would be adaptable to the plain paddy field of middle, honam and yeongnam province of Korea under ordinary cropping system.

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.

A rice variety ‘Dabo‘ is a japonica rice (Oryza sativa L.) with good eating quality, lodging tolerance, and resistance to rice stripe virus (RSV) and blight bacterial disease(BB). It is developed by the rice breeding team of Yeongdeog Substation, National Institute Crop Science, RDA in 2012. This variety derived from a cross between ‘Yeongdeog31’ with good plant type and ‘Milyang165’ with good eating quality conducted in 2001/2002 winter season. A promising line, YR23160-31-2-1-5-B-3, selected by pedigree breeding method was designated as the name of ‘Yeongdeog53’ in 2009. After the local adaptability test was carried out at seven locations from 2010 to 2012, ‘Yeongdeog53’ was released as the name of ‘Dabo’ in 2012. ‘Dabo’ is short culm length as 69 cm and medium-growth duration. This variety is resistant to races, K1, K2, and K3 of bacterial blight and stripe virus and moderately resistant to leaf blast disease. ‘Dabo’ has translucent and clear milled rice kernel without white core and belly rice, and good eating quality as a result of panel test. The yield potential of ‘Dabo’ in milled rice is about 5.90 MT/ha at ordinary fertilizer level of local adaptability test. This cultivar would be adaptable to south plain, east-south costal area, and south mid-mountainous area.

This study was conducted to develop the early maturing rice lines with genes conferring resistance to bacterial blight and rice stripe virus to enhance the adaptability in plain area. Unkwang carrying Xa3 was used as a recurrent parent and SR30075 carrying Xa4+xa5+Xa21+Stvb-i was used as a donor parent. RL1(Resistant Line, BC₁F₇), RL2, RL3, RL4, and RL5(BC₂F₆) were bred through bio-assay of K3a race inoculation and phenotypic selection of agronomic traits. The presence of introduced genes was confirmed by testing the resistance levels against bacterial blight and rice stripe virus and then double-checked by using DNA marker. RL1 has all target genes, Xa3+xa5+Xa21+Stvb-i. RL2, RL3, and RL5 have Xa3+Xa21+Stvb-i whereas RL4 has only Xa21. Rice lines carrying Stvb-i showed resistance reaction to rice stripe virus. The combinations of bacterial blight resistant genes(Xa3+xa5+Xa21 and Xa3+Xa21) were found to be promising, as the rice lines carrying these genes enhanced a strong resistant reaction against 16 bacterial blight isolates. Also, the inoculation of K3a race did not alter the brown rice yield, ripened grain ratio and kernel quality of brown rice compared to control. Although RL1 containing all the target resistance genes showed excellent resistance performance, it is not suitable to cultivate in plain area due to instability to lodging, 80% yield level than Unkwang, and low grain quality. RL5 backcrossed twice with Unkwang was found to be a promising line due to its effective resistance gene combination, Xa3+Xa21+Stvb-i and good agronomic traits such as stability to lodging, higher yield and quality compared to Unkwang.

‘Chindeul’, a new japonica rice cultivar developed from a cross between HR22538-GHB-36-4 having brown planthopper (BPH) resistance and Iksan471 having a good eating-quality and high yield, was developed by the rice breeding team of Department of Rice and Winter Cereal Crop, NICS, RDA in 2012. This variety has about 124 days growth duration from transplanting to harvesting in west-southern coast, Honam and Youngnam plain of Korea. It has 83 cm culm length and tolerance to lodging. In reaction to biotic and abiotic stresses, it shows resistance to bacterial blight pathogen races from K1 to K3, stripe virus and brown planthopper. The milled rice of ‘Chindeul’ exhibits translucent, relatively clear non-glutinous endosperm and medium short grain. It has lower protein content of 5.9% and good palatability of cooked rice compared with Nampyeongbyeo. The milled rice yield performance of this variety is about 5.61 MT/ha in local adaptability test for three years. ‘Chindeul’ would be useful genetic resources for multi-resistance breeding program against disease and insect.

‘Huimangchan’ is a new japonica rice variety developed and registered by the rice breeding team of Department of Rice and Winter Cereal Crop, NICS, RDA in 2011. This variety was derived from the three-way cross of ‘Milyang165’, ‘Shindongjin’ and ‘YR19105-Acp222’. This variety has about 126 days of growth duration from transplanting to harvesting in Honam and Youngnam plain of Korea. It is about 91 cm in culm length and tolerance to lodging. In reaction to biotic stresses, it shows moderate resistance to blast, resistance to bacterial blight pathogen races from K1 to K3, and rice stripe virus, but susceptible to other major diseases and insect pests. The milled rice of ‘Huimangchan’ has high quality, midium short grain. The milled rice yield of this variety is about 6.18 T/ha in local adaptability test for three years. ‘Huymangchan’ would be adaptable to Middle plain, Honam plain and Youngnam plain area of Korea.

‘Sanhomi’, a new japonica rice cultivar developed from a cross between Sangmibyeo and F₁ plant derived from the cross between Sangju24 and Hwayeongbyeo having bacterial blight and rice stripe virus resistance was developed by the rice breeding team of Sangju Substation, NICS, RDA in 2012. This variety has about 114 days of growth duration from transplanting to harvesting in southern mid-mountainous area of South Korea. It has 70 cm culm length and tolerance to lodging. In reaction to biotic and abiotic stresses, it shows multiple resistance to blast, bacterial blight and rice stripe virus. The milled rice of ‘Sanhomi’ exhibits translucent and, relatively clear non-glutinous endosperm, and medium short grain. This variety has a higher milled rice recovery (67.3%), better palatability of cooked rice and similar amylose content (19.9%) compared with Odaebyeo. The milled rice yield performance of this variety was about 5.60 MT/ha in local adaptability test for three years. ‘Sanhomi’ would be adaptable to southern mid-mountainous of South Korea.

This study was conducted to develop breeding lines carrying bacterial blight resistance genes, Xa2, Xa3, xa5, and Xa21 for enhancing the resistance of early maturing glutinous japonica rice. Resistant lines were developed by backcrossing into early maturing glutinous elite cultivar, Sangjuchalbyeo and phenotypic selection for bacterial blight resistance and agronomic traits. Selected lines were confirmed the incorporation of the resistance genes using DNA markers and evaluated the resistance reaction against four Korean and eleven Philippine bacterial bight races. HR24465 line carrying Xa2 was resistant to Korean races K1, K2, and Philippine race 9a. HR24666 line carrying Xa3 was moderately resistant or resistant to races except for Korean race K3a and Philippine race 6. Resistant lines carrying xa5 were resistant to all races except for Philippine race 6. HR24669 line carrying Xa21 was moderately resistant or resistant to races except for Korean race K1 and Philippine race 10. Yield-related traits of breeding lines exhibited similar characteristics to Sangjuchalbyeo. These resistant lines could be useful breeding materials for improving the resistance of early maturing glutinous japonica rice against Xanthomonas oryzae pv. oryzae.