‘Amissal’ is a regionally specialized rice cultivar developed to strengthen the competitiveness of local rice and is characterized by its distinct long-grain japonica type. It was bred through a single backcross between ‘Boramchan’—a high-yielding japonica cultivar with excellent cultivation stability used as the recurrent parent—and ‘HR30198-AC33’ (DGS79), a breeding stock with extra-long and spindle-shaped grains used as the donor parent for japonica grain shape diversification. Population and pedigree breeding methods were used during the breeding process. During the selection stage, molecular marker-assisted selection targeting the major grain shape genes, GS3 and qSW5 was applied, enabling the identification of lines carrying the gs3-qSW5 allele combination associated with long grain shape. ‘Amissal’ was developed through yield trials, local adaptability tests, selection trials addressing regional needs, and on-farm research aimed at developing long-grain japonica rice for export. The heading date of ‘Amissal’ was August 17, two days later than that of ‘Nampyeong’. Compared to ‘Nampyeong’, ‘Amissal’ exhibited greater biomass due to longer culms, more spikelets per panicle but fewer panicles per hill, and a heavier 1,000-grain weight. It demonstrated strong resistance to bacterial blight (races K1, K2, and K3) but was susceptible to viral diseases and insect pests. In terms of yield, it outperformed ‘Nampyeong’. The average brown rice grain length was 6.14 mm, classifying it as long-grain type. The length-to-width ratio was 2.43, corresponding to a semi-spindle shape, which clearly distinguishes it from existing Korean japonica cultivars. While its milling recovery rate was similar to that of ‘Nampyeong’, a high proportion of broken rice due to its long grain shape resulted in a lower head rice. ‘Amissal’ had low protein content and provided the sticky and soft texture typical of japonica rice, with excellent scores in sensory evaluation tests. As a differentiated, regionally specialized rice cultivar featuring a long-grain japonica type and superior eating quality, ‘Amissal’ is expected to contribute to the advancement of the local rice industry, particularly through applications in rice export and the utilization of broken rice and rice straw (Registration No. 10167).

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).

The decrease in seed vigor and grain quality during storage has become an increasingly critical issue due to the extended storage periods resulting from declining rice consumption and climate change in Korea. Despite its importance, few studies have investigated rice seed aging in a large number of Korean rice cultivars. In this study, 53 japonica rice cultivars were evaluated for seed germination, vigor, and grain quality-related traits under accelerated-aging conditions. Seed germination rate was evaluated 7 days after imbibition, following accelerated aging treatments at 42℃ and 95% relative humidity for 8, 12, and 16 days. The average germination rates were 72.9% in the control (0 d), 71.7% after 8 days, 59.0% after 12 days, and 5.6% after 16 days of treatment. Grain quality-related traits, including texture and pasting properties, were also evaluated in rice subjected to the accelerated aging treatment. Adhesiveness and stickiness decreased, whereas hardness and toughness increased, as seed aging progressed. Cluster analysis based on germination rates after accelerated aging identified three distinct clusters, with cultivars in Cluster 3 maintaining a high germination rate of 70.6% even after 12 days of aging, showing clear differences from the other clusters. A principal component analysis (PCA) was conducted to investigate the relationship between germination rate and grain quality-related traits. The results showed that the germination rate and hardness tended to be negatively associated across all three clusters. These results suggested that cultivars with higher germination rates tend to maintain a softer cooked rice texture after aging. Our results provide insight into the relationship between seed aging and grain quality, highlighting elite cultivars that maintain both germination ability and grain quality during storage as valuable resources for breeding programs.

Rapid climate change has diversified the dynamics of brown planthoppers, necessitating the development of rice cultivars with enhanced resistance. Brown planthoppers contribute to reduced grain yield and quality, and the rapid ecological changes caused by global warming are expected to exacerbate this damage. In Korea, rice cultivars resistant to brown planthoppers have primarily been bred using Bph1, bph2, and Bph18. Despite the known resistance of Bph3 to brown planthoppers, this gene is underutilized in rice breeding programs. Therefore, in this study, we aimed to analyze the association between brown planthopper resistant genes and rice agronomic traits by breeding segregated populations incorporating Bph3, Bph18, and BPH26. Segregated populations were derived from crosses between ‘Jeonju686’ (carrying Bph3 and BPH26) and ‘JJ621MR’ (carrying Bph18). Our analysis revealed that Bph18 was significantly associated with a reduced fertility rate. However, Bph3 did not significantly affect fertility-related traits. As Bph3 has been reported to confer strong resistance to brown planthoppers, it is expected to be actively utilized in future resistance breeding programs. Ultimately, maximizing the efficiency of molecular breeding techniques is expected to provide valuable insights into the development of rice cultivars with enhanced resistance to brown planthoppers.

Rice cultivar ‘Saeodae1’ was generated by crossing ‘Saeodae’, which has good taste and a medium-short round grain, and ‘Unbong51’ which has a combined disease resistance and translucent grain. The aim of this was to develop an early maturing rice cultivar with medium-short round grain and high quality rice which adapts to the mid-northern inland plain, northern-middle highland, northern-east coastal region of Korea, and was undertaken by the rice breeding team of Cheolwon Substation, National Institute of Crop Science (NICS), RDA, in 2022. In the normal growing season in the mid-northern inland plain of Korea, the heading date of ‘Saeodae1’ was July 25 around the same time in ‘Odae’. ‘Saeodae1’ had a 75 cm culm length, 1 cm longer than that of ‘Odae’, and 75 spikelets per panicle, similar to that of ‘Odae’. The ripened grain ratio (84.7%) of ‘Saeodae1’ was higher than that (72.5%) of ‘Odae’. The head rice ratio (60.9%) of ‘Saeodae1’ was higher than that of ‘Odae’, which is advantageous in securing yield. 1,000 grain weight (25.9 g) was similar to that of ‘Odae’, but it has a smaller degree of white core rice, leading to an improved consumer preference. ‘Saeodae1’ exhibited resistance to blast and bacterial blight (K1, K2, K3 races), but was susceptible to the K3a race of bacterial blight, stripe virus, dwarf and black streak dwarf viruses, and plant-hoppers. The milled rice of this variety was translucent, with a medium-short grain shape. The cooked rice grains of ‘Saeodae1’ exhibited a good palatability index (0.13) and similar amylose content (18.2%) to that of ‘Odae’. Grain milling characteristics, including head rice milling recovery ratio and head rice ratio (82.0%) were better than those of ‘Odae’. Average milled rice productivity of ‘Saeodae1’ was 5.59 t/ha at six sites in the normal growing season (Registration No. 10182(2024.5.14.)).

The rice cultivar ‘JJ644wx’ was developed to improve disease resistance and lodging tolerance of Korean japonica glutinous rice cultivars. ‘JJ644wx’ was derived from a cross between ‘HR27814-B-47-1-1’ (‘Sinjinbaek’), a multiple disease-resistant mid-late maturing elite line, and ‘HR29676-AC29’, a medium-maturing glutinous line with lodging tolerance. To shorten the breeding period, an anther culture method was applied to F₁ plants. ‘JJ644wx’ was selected through the pedigree method, yield trials, and local adaptability tests, with high selection pressure for disease resistance and lodging tolerance. The heading date of ‘JJ644wx’ was August 11th, four days later than that of ‘Sinseonchal’. ‘JJ644wx’ exhibited strong tolerance to lodging with a short culm length. The 1,000-grain weight of brown rice of ‘JJ644wx’ was heavier than that of ‘Sinseonchal’, and its yield was 553 kg/10a, which was 10% higher than that of ‘Sinseonchal’. ‘JJ644wx’ had a higher milling performance than ‘Sinseonchal’, but a lower head rice ratio due to a higher percentage of broken rice. ‘JJ644wx’ tended to be situated between ‘Sinseonchal’ and ‘Dongjinchal’ in terms of pasting and texture characteristics. ‘JJ644wx’ is the only Korean japonica glutinous rice cultivar resistant to the most virulent bacterial blight race, K3a; it also showed resistance to rice blast and stripe virus. ‘JJ644wx’ is expected to be a valuable resource that could contribute to improving the cultivation stability of Korean japonica glutinous rice in response to climate change (Registration No. 9606).

‘Saebonghwang’ was developed as a mid-late ripening rice variety with good cultivation stability and yield in transplanting and under direct seeding cultivation. It was bred by backcrossing ‘Hopum’, which has excellent cultivation stability and adaptability to direct seeding, as a repeat parent, and ‘Hitomebore,’ a Japanese rice variety with excellent taste, as a donor. The heading date of ‘Saebonghwang’ was August 11 under ordinary planting, which is two days earlier than that of ‘Nampyeong’, and August 13 under wet-direct seeding cultivation, which is the same as that of ‘Dongan’. ‘Saebonghwang’ had a culm length of 74 cm under wet-direct seeding cultivation, which is larger than that of ‘Dongan’ (69 cm), and had good cultivation stability, including lodging resistance. ‘Saebonghwang’ is resistant to bacterial leaf blight and rice stripe virus and shows moderate resistance to rice blast. Furthermore, ‘Saebonghwang’ has better grain appearance, superior taste and better milling characteristics than ‘Nampyeong’. The yield of ‘Saebonghwang’ when cultivated under ordinary planting, wet-direct seeding, and double cropping was 5.65, 5.37, and 5.37 MT/ha, respectively. Under wet direct sowing by drone cultivation, ‘Saebonghwang’ showed good initial survival rate and cultivation stability. The yield was 4.49 MT/ha, slightly lower than that obtained under transplanted cultivation (5.03 MT/ha), but was not statistically different; therefore, ‘Saebonghwang’ was adjudged to be adaptable to drone wet-direct seeding. ‘Saebonghwang’ can be used in various ways to suit the working conditions of farms, increase farm work efficiency, and expand the area of wet direct-seeding cultivation (Registration No. 9171).

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).

‘Miwoo’ is a mid-late maturing, high-biomass-yielding rice (Oryza sativa L.) cultivar with high feed value and resistance to multiple diseases and insect pests. It was developed for use as whole crop silage (WCS) from a cross between ‘Suweon519’, a line with high biomass yield and multiple disease resistance, and ‘Suweon518’, a medium flowering, high yielding Tong-il type line, which is resistant to blast (BL), bacterial blight (BB) (race K1), rice stripe virus (RSV) and brown planthopper (BPH). In the central plain region of Suwon, ‘Miwoo’ cultivar exhibited a growth period of approximately 122 days from seeding to heading, culm length of 99 cm, panicle length of 28 cm, 12 panicles per hill, 143 spikelets per panicle, and 1,000-grain weight of 25.9 g as brown rice. This mid-late-flowering rice variety was resistant to lodging during the yellowing ripening stage, an optimal period for harvesting. In addition, ‘Miwoo’ was strongly resistant to leaf and neck blast, BB (race K1, K2, K3, K3a), RSV, BPH and small BPH. Its average dry matter yield over 3 years reached 19.9 MT/ha, which is 36% higher than that of ‘Nokyang’. ‘Miwoo’ is a high-amylose cultivar with 70.7% total digestible nutrients (similar to that of Nokyang) and grows well on the central and southern plains of the Korean Peninsula. It should be harvested 30 days after heading to improve its feed value and digestion rate in livestock. (Registration No. 7683)

‘Keunpum’ is a mid-late maturing, high yielding, giant embryo rice (Oryza sativa L.) cultivar which is adapted to central plains and was developed to be used as (germinated) brown rice. It is resistant to multiple diseases with a good grain quality. This cultivar was derived by crossing a giant embryo rice variety ‘Keunnun’ and a mid-late maturing, multi-disease resistant rice cultivar ‘Samkwang’-it has good palatability of cooked rice. The growth period of this cultivar is approximately 117 d from seeding to heading, with a culm length of 88 ㎝, panicle length of 20 ㎝, 13 panicles per hill, 136 spikelets per panicle, and 1,000-grain weight of 19.1 g brown rice. This variety has low tolerance to cold stress and premature germination similar to ‘Keunnun’ but exhibits high resistance to lodging. In addition, ‘Keunpum’ is resistant to bacterial blight (race K1, K2, K3), rice stripe virus, and is moderately resistant to leaf and neck blast. Its average milled rice yield for three years reached 5.34 MT/ha, which is 10% higher than that of ‘Keunnun’. In the brown and germinated brown rice of this cultivar, the total dietary fiber content are 6.45% and 6.71%, and the GABA (γ-amino butyric acid) content are 6.61 and 39.47 mg/100 g, respectively. In addition, the total contents of polyphenol, flavonoid, and tannin were higher in ‘Keunpum’ brown rice than in ‘Keunnun’. The DPPH and ABTS radical scavenging activities were 75.23, 116.08 mg TE/100g, respectively. These functional components and antioxidant activities play an important role in inhibiting diseases and the aging process of the human body. Therefore, it is expected to be used as a basic data in the manufacture of secondary processed products using germinated brown rice (Grant No. 7684).

Interspecific and intersubspecific crosses have been an important strategy for rice breeding programs to obtain useful characters by expanding genetic diversity. However, the wide cross routinely causes undesirable characters in rice, such as spikelet sterility and poor quality. In this study, we developed near-isogenic lines of R-gene (Xa4+xa5+Xa21+Pi40+Bph18) introgression population to investigate the genetic relationship between the occurrence of poor characters and R-genes induced by MAS. The ANOVA analysis revealed that Pi40, Bph18, and Xa4 were associated with spikelet fertility (SF), ratio of ripened grain (RRG), third internode length (TIL), panicle extraction (PE), and protein content (Pro), whereas others showed no association with the 14 traits tested. In the three-way ANOVA, the impact of two R-genes (Pi40 and Bph18) on the poor characters was independent, with no interaction with others. Quantitative trait locus (QTL) analysis identified QTLs for PE and TIL traits near Pi40, and in particular, QTLs for five traits (SF, RRG, TIL, PE, and Pro) were negatively affected around Bph18. The occurrence of a poor character in R-gene pyramiding lines could be associated with linkage drag caused by the Bph18 gene. We speculate that the development of DNA markers that effectively eliminate poor characters will not only improve breeding efficiency using MAS, but will also help improve traits of japonica rice through wide crossing.

Early maturing rice is widely utilized to diversify cropping systems in the Honam Plain, Korea. It is based on the principle of a short growth duration. There is concern regarding quality deterioration of early maturing rice owing to the high temperature during the ripening stage as compared to that for mid and mid-late maturing rice. This study was conducted to analyze six pasting property-related and eight quality traits of six early maturing rice varieties (Jopyeong, Odae, Unkwang, Haedamssal, Jinkwang, and Haedeul) on early, ordinary, and late cultivations, and to interpret the relationships between genotypes and environments. As the cultivation time increased, the ratio of head rice (HR) and glossiness of cooked rice (Toyo value, TY) increased. The cumulative mean temperature of the ripening stage showed a strong negative correlation with HR and TY at all cultivation times. Pasting temperature, peak viscosity (PV), trough viscosity, final viscosity, and breakdown (BD) decreased, whereas setback (SB) increased as the cultivation time was delayed. Pasting properties were affected more by climate conditions in the ripening stage than during the growth stage. Additive main effects and multiplicative interaction analysis revealed that pasting property-related and quality traits were affected more by environment than genotype. Jinkwang and Haedamssal in early and ordinary cultivation and Jinkwang and Haedeul in late cultivation exhibited higher HR and TY and a lower protein content. They also showed higher PV and BD and lower SB, which are characteristics of good eating quality japonica rice. Jinkwang, Haedamssal, and Haedeul are premium-quality, early maturing rice varieties that were recently developed. The cultivation of these varieties could improve the grain quality of early maturing rice at high temperatures during the ripening stage in the Honam Plain.

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).

‘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).

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.

Rice research in Korea during the past 100 years has gone through tremendous changes and improvements as the country underwent a turbulent history of transformation. Full-scale R&D modernization began in the 1970s, when the government focused policy on achieving self-sufficiency in rice in order to establish the foundation for national economic growth. A major landmark was reached by the development of the rice variety “Tongil” and its cultivation technology, which was at the core of the unprecedented Korean “Green Revolution”. Since achieving self-sufficiency in rice, the breeding goal of Korea moved from increasing yield to improving grain quality as more consumers began to seek high quality food products in the 1980s. This change led to the establishment of the high quality rice breeding platform for enhancing the global competitiveness of Korean rice to cope with the opening of domestic rice market in the 2000s. Currently, the major breeding goals in rice are developing premium quality cultivars for table rice and specialized cultivars for boosting processed food industry. To date, the National Institute of Crop Science has released a total of 300 rice cultivars, including 202 table rice and 98 specialized usage cultivars. Diverse technologies have been developed and utilized for breeding new rice cultivars to meet changing needs. In the next 100 years of rice breeding, the convergence of traditional crop improvement technologies and the new breeding technologies utilizing recent advances in biotechnology will play a crucial role in enhancing breeding efficiency.

‘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).

‘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).

‘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)

It is reported that the absence of lipoxygenase-3 (LOX-3) may contribute to a reduction in stale flavor after the storage of rice. To improve the quality of stored rice of the Korean japonica rice cultivar, we conducted a breeding program to develop near-isogenic rice without LOX-3 in the genetic background of Saenuri, a mega variety of Korea. In the first step of the breeding program, we used a donor parent of LOX-3 null, Daw Dam, and a recurrent japonica parent, Sindongjin, to develop HR27873-AC12 by backcross (BC₁), color test for introgression of lox-3, and anther culture for rapid fixation. In the second step, we used the donor parent, HR27873-AC12, and the recurrent parent, Saenuri, to develop HR28896-31-3-1-1 by backcross (BC₁), marker-assisted selection (MAS) for lox-3, and phenotypic selection (PS) for agronomic traits. Finally, in the third step, we developed HR30960-186-2-1-2-1 (Jeonju624), derived from a cross between Saenuri and HR28896-31-3-1-1, by MAS for lox-3 and PS with high selection pressure for agronomic characteristics. Jeonju624 was confirmed with the introgression of lox-3 by molecular marker. Jeonju624 was a mid-late maturing rice with similar agronomic characteristics to Saenuri, lodging tolerance with short culm, erect plant architecture, and resistance to bacterial blight and rice stripe virus. The yield components of Jeonju624 were mostly similar to Saenuri, except for the 1,000-grain weight of brown rice. The appearance of the grain of Jeonju624 was better than that of Saenuri, and the characteristics of cooked rice were similar to those of Saenuri. In the genetic background analysis using 406 KASP (Kompetitive Allele-Specific PCR) markers, Jeonju624 was confirmed to be the near-isogenic line (NIL) of Saenuri with a 95.8% recovery rate. Jeonju624 is the NIL of Saenuri without LOX-3, and overcomes the linkage drag of Daw Dam with similar agronomic characteristics and genetic background to Saenuri. Jeonju624 can be utilized as a practical cultivar to improve the quality of stored rice, breeding material for the introgression of lox-3, and genetic material to elucidate the effect of introgressed genes.

‘Jungmo1033’, a japonica rice variety, was developed by the rice breeding team at the National Institute of Crop Science (NICS) in 1992. It is derived from a cross between a native variety ‘Jagwangdo’, which has translucent milled rice and medium maturity; and ‘Hwayeong’, which is an elite line with bacterial blight resistance and mid-late maturity. The heading date of ‘Jungmo1033’ was August 10 in the middle plain area of Korea, which was two days later than that of ‘Hwaseong’. ‘Jungmo1033’ has a culm length of 79 cm, which was 5 cm shorter than that of ‘Hwaseong’, and 105 spikelets per panicle. ‘Jungmo1033’ showed resistance to bacterial blight (K1, K2, and K3 races) and stripe virus, but susceptibility to the K3a race of bacterial blight, dwarf and black-streaked dwarf viruses, and planthoppers. The milled rice of this variety exhibited translucency and a medium short grain shape. It had an excellent appearance and lower amylose content (19.1%) than that of ‘Hwaseong’. The characteristics related to grain milling were better than those of ‘Hwaseong’, especially head rice milling recovery ratio and head rice ratio (94.8%). ‘Jungmo1033’ showed a milled rice productivity of 5.38 MT/ha at 11 sites under ordinary cultivation conditions. (Registration No. 5723)

“Samkwang1,” a japonica rice variety, was developed as a cross between “Samkwang” and F1 of Suwon152 (IT008283), which has a medium maturing and lodging resistance and Samkwang (IT284608), a high quality variety with bacterial blight resistance and mid-late maturing property by the rice breeding team at NICS in 2015. The heading date of “Samkwang1” was August 8 in the middle plain area, which was 2 days early than that of “Hwaseong.” “Samkwang1” had a culm length of 77 cm, which was 7 cm shorter than that of “Hwaseong,” and it had 128 spikelets per panicle. The viviparous germination rate of “Samkwang1” was 2.1%. “Samkwang1” showed resistance to blast, bacterial blight (K1, K2, and K3 race) and stripe virus, but was susceptible to the K3a race of bacterial blight, dwarf and black streak dwarf viruses, and plant hoppers. The milled rice of this variety exhibits translucent and medium short grains. The cooked rice grains of “Samkwang1” have an excellent palatability index (0.35) and lower protein content (6.2%) than that of “Hwaseong.” The characteristics related to grain milling were better than those of “Hwaseong,” especially the head rice milling recovery ratio and head rice ratio (94.2%). “Samkwang1” showed 5.62 MT/ha of milled rice productivity at 11 sites under ordinary cultivation conditions (Registration No. 6798).

“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).

Rice panicle architecture is an important factor affecting yield potential. Korean rice cultivars have a narrow genetic background for panicle architecture. To enhance the yield potential of Korean rice cultivars, we developed and characterized rice lines with new panicle architecture. Rice with improved panicle architecture has clustered spikelets and dense panicles (CD type). CD rice was derived from a cross between “Binhae Col.#1” carrying dense panicles, and “ARC10319” that has the clustered spikelets gene (Cl). CD rice lines had short and semi-erect panicles with two to five high density spikelets clustered at the tips of primary and secondary rachis branches. CD rice lines had dramatically increased numbers of spikelets; almost twice as many as those of Korean rice cultivars. The increase in spikelet number was mainly caused by the increased spikelets and branches on secondary rachises compared to those on primary rachises. The increase in spikelet number was expected to enhance the yield of CD rice by expanding sink capacity. However, the yield of selected lines; CD9, CD27, CD34, and CD39, did not reach the level of the Korean high-yielding cultivars “Boramchan” and “Hanareum2,” due to the reduction in panicle number and grain weight, and poor ripening. Although no substantial yield increase was observed in CD rice, the panicle architecture of CD rice, clustered spikelets, and dense panicles could be new genetic resources as breeding material for diversifying panicle architecture and enhancing yield potential.

‘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).

Cheongpum’, a japonica rice variety, was developed from a cross between Yeongdeog45 and ‘Samkwang’ by the rice breeding team at NICS in 2015. The heading date of ‘Cheongpum’ was August 10 in the middle plain area, which was two days later than that of ‘Hwaseong’. ‘Cheongpum’ had a culm length of 79 cm, which was 5 cm shorter than that of ‘Hwaseong’, and 116 spikelets per panicle. The viviparous germination rate of ‘Cheongpum’ was 27.9%. It showed resistance to blast, bacterial blight (K1, K2, K3 race), and stripe virus, but susceptibility to the K3a race of bacterial blight, dwarf, and black streak dwarf viruses, and plant hoppers. The milled rice of this variety exhibited a translucent and medium short grain shape. The cooked rice grains of ‘Cheongpum’ had an excellent palatability index (0.41) and lower amylose content (18.8%) than that of ‘Hwaseong’. The grain milling characteristics were better than those of ‘Hwaseong’, especially the head rice milling recovery ratio and head rice ratio (94.1%). ‘Cheongpum’ showed 5.36 MT/ha of milled rice productivity at 11 sites under ordinary cultivation (Registration No. 6799).

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).

‘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).

‘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.