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.)).

‘Haedeul’ is a high-quality rice variety with early maturing that adapts to the central region of Korea. This cultivar was crossed between ‘Gopum’, which has excellent taste, and ‘Hoban’, which has a low viviparous germination rate and is moderately tolerant of cold, by the rice breeding team of the Department of Central Area Crop Science, NlCS, RDA, in 2017. In early-transplanting cultivation, the heading date of ‘Haedeul’ was July 24 in central area of Korea, which was seven days later than that of ‘Jopyeong’. ‘Haedeul’ had a culm length of 75 cm and 99 spikelets per panicle. The viviparous germination rate of ‘Haedeul’ was 7.7%. It showed resistance to blast and bacterial blight (K1, K2, K3 race), 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 exhibited a translucent and medium short grain shape. The cooked rice grains of ‘Haedeul’ had an excellent palatability index (0.61) and lower amylose content (18.0%) than that of ‘Jopyeong’. The grain milling characteristics were better than those of ‘Jopyeong’, especially the head rice milling recovery ratio and head rice ratio (94.9%). ‘Haedeul’ milled rice productivity averaged 5.32 MT/ha at five sites under ordinary cultivation (Registration No. 7681).

Early maturing rice cultivars grown in plain areas have an undesirable appearance due to high temperatures during the grain-filling stage. Therefore, developing early maturing rice cultivars with desirable appearance traits in plain areas is the primary goal of rice breeding programs. This study aimed to develop an early maturing rice cultivar adaptable to early transplanting cultivation in the Chungnam plain area. To develop “Yeoreumi,” two breeding materials were used, good-quality “Joami” from the Chungnam plain area and “Hokuto” having the fastest heading date among the genetic resources and originating from Japan. These two resources were crossed in 2010 to develop the “Yeoreumi” cultivar using the pedigree method. A yield trial was conducted in 2015-2016, and a local adaptability test was conducted in 2017-2019. The heading date of “Yeoreumi” was July 10, when it was transplanted early in the Chungnam plain area, and it could be harvested at August end, which was sufficient to produce a fresh stock of rice before “Chuseok, which is the Korean Thanksgiving Day.” The yield of milled rice was approximately 5.29 MT/ha in the local adaptability test, which was 0.47 MT/ha higher than that of “Jinbuolbyeo.” Additionally, its grain quality was good, with 89.9% head rice and 67.6 glossiness of cooked rice. Overall, the results of this study indicated that “Yeoreumi” was suitable for early transplanting cultivation in the Chungnam plain area for “Chuseok,” and could be used as a representative early maturing rice cultivar in Chungcheongnam-do (Registration No. 8597).

This study was performed to determine the optimum transplanting dates of ‘Bbareumi’ in the Chungnam Plain area. ‘Bbareumi’ was transplanted into a rice research field of Chungnam Agricultural Research and Extension Services at intervals of approximately 15 days from April 17^th to August 1^st in 2019 and 2020. The heading dates of ‘Bbareumi’ were June 23^rd to September 2^nd depending on transplanting dates. The highest milled-rice yield was 5.61 MT/ha on May 1^st and the lowest was 3.65 MT/ha on August 1^st. As the transplanting date was delayed, protein content increased; however, the number of days from transplanting to heading decreased. Protein content and the number of days from transplanting to heading showed a highly significant correlation (R² = 0.802^**). Therefore, it was found that early transplanting was beneficial to produce lower protein content because head rice percentage was 84-87% for early (April 17^th to May 16^th), 74-80% normal (June 1^st to June 16^th), and 86-95% for the late transplanting date (July 1^st to August 1^st). The mean temperature during the ripening stage differed according to the transplanting dates, and early transplanting showed a lower temperature than the normal one (May 16^th to June 15^th) and a higher head rice percentage. Therefore, extremely early maturing rice cultivars should be transplanted between late April and early May to obtain lower protein content and higher head rice percentage. These results will be useful for rice breeding programs, as it is generally recognized that early transplanting results in poor rice quality; however, this study revealed contrasting results.

‘Bbareumi’ is an extremely early maturing rice cultivar with the fastest harvesting time in Korea. To develop ‘Bbareumi’, ‘Joami’ with good quality in Chungnam plain area and ‘Hokuto’ originating from Japan with the fastest heading date among genetic resources were used as breeding materials. After crossing them in 2010, the ‘Bbareumi’ cultivar was developed using the pedigree method. A yield trial was conducted from 2015 to 2016, and a local adaptability test was conducted from 2016 to 2018. The heading date of ‘Bbareumi’ was seven days earlier than ‘Jinbuolbyeo’, showing an average of June 23^rd, and it could be harvested from the end of July to the beginning of August when transplanted early in Chungnam plain area. ‘Bbareumi’ had a short culm length of 63.3 cm and panicle length of 19.3 cm. Milled rice yield was approximately 4.87 MT/ha and the percentage of head rice was 89.2% under normal fertilizer condition. ‘Bbareumi’ will be used as a premium rice brand with newly harvested rice before ‘Chooseok’, Korean Thanksgiving Day and is expected to contribute to the revitalization of double-cropping in the Chungnam plain area (Registration No. 8130).

This study was conducted to reset the transplanting period to produce high-quality rice in the South regions due to the rise in air temperature caused by global warming. From May 15 to June 25, transplants were performed five times every ten days. Quantity and quality were comprehensively reviewed, including watering season, ripened grain rate, head rice rate, head rice yield, protein content, and palatability. In the southern plains, medium-late and medium maturing cultivars yielded the most when transplanted on June 15, while early maturing cultivars yielded the most when transplanted on June 25. Considering the quality and quantity of rice, the optimal transplanting window for medium-late maturing cultivars is June 10-15, for medium maturing cultivars it is June 15-20, and for early maturing cultivars it is June 25. In the middle of the southern region, the highest yield was on June 25 for medium-late maturing and June 15 for medium maturing and early maturing. However, considering the quality, the best time for transplanting is June 10 for medium-late maturing, June 5 for medium maturing, and June 15 for early maturing. As a result of the rise in average temperature, the transplantation period was delayed by at least 4 to 16 days in all varieties and regions relative to the traditional transplantation duration. In summary, it is determined that a suitable transplanting period must be established in response to the increase in average temperature to ensure the production of high-quality rice.

‘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).

‘Joan’, a rapeseed (Brassica napus L.) F₁ hybrid cultivar suitable for producing cooking oil developed by the National Institute of Crop Science, is early maturing with characteristically high yield and oleic acid content. It was bred in 2009 by crossing the male sterile line ‘Mokpo-CGMS’ as the female parent with the restorer line ‘8630-B-6-5-3-6’ as the male parent. The average flowering and maturation dates of ‘Joan’ were April 10^th and June 1^st, respectively, 3 and 4 days earlier, respectively, than that of the control cultivar ‘Sunmang’. The yield of ‘Joan’ obtained in regional adaptation trials was 279 kg/10 a, which is 6% higher than that obtained for ‘Sunmang’. ‘Joan’ is resistant to stem rot disease and more tolerant to lodging than ‘Sunmang’. Moreover, the total oil content of ‘Joan’ is 44.5%, whereas the oleic acid content is 69.5%, which is 2.3% higher than that of ‘Sunmang’. However, erucic acid has not been detected. ‘Joan’ can be grown in paddy fields located in Jeollanam-do, Jeollabuk-do, Gyeongsangnam-do, and Jeju-do in Korea (Registration No. 6896).

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 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.

‘Haedamssal’ is an early maturing and rice stripe virus disease-resistant cultivar adaptable for early-transplanting cultivation that was developed by the rice breeding team of the Department of Southern Crop, NICS, RDA, in 2014. This cultivar was derived from the cross YR25869 (YR21247-B-B-B-49-1/Sasanishiki BL4//Koshihikari) and YR25868 (Unkwang//YR21247-B-B-B-49-1/Sasanishiki BL4) made in the 2005/2006 winter season and was advanced to the F₅ generation by a bulk breeding method using rapid generation advance. To incorporate rice stripe virus resistance, marker-assisted selection on the RSV gene was conducted in 3-way and 6-way cross F₁ generation using the tightly linked marker RM6897. From testing in the replicated yield trial in 2011, a promising line YR26258-B-B-B-33-3 was selected and it was designated as ‘Milyang276’. A local adaptability test of ‘Milyang276’ was performed at three locations from 2012 to 2014 and it was named as ‘Haedamssal’, which was a good eating quality variety. The culm length was 67 cm in yield trials, which was 4 cm shorter than ‘Jopyeong’. The number of spikelets per panicle was lower than ‘Jopyeong’, whereas the number of tillers per hill was higher. This variety was resistant to RSV disease, bacterial blight, and leaf blast disease. The milled rice yield of ‘Haedamssal’ was 5.48 MT per ha at the early transplanting in the local adaptability test. ‘Haedamssal’ is well adapted to early transplanting cultivation in the southern plain area (Registration No. 6811).

‘Jinkwang’, a japonica rice variety, was developed by a cross between ‘Hopum’ (IT23527) and the F1 hybrid of ‘Unkwang’ (IT217814) and ‘Koshihikari’ (IT157335) by the rice breeding team at NICS in 2016. ‘Unkwang’ shows an early maturity and high yield and ‘Koshihikari’ is a high-quality variety. The growth duration of ‘Jinkwang’ in the paddy field was 114 days in the middle plain region in Korea, which was six days later than that of ‘Jopyeong’. The culm length of ‘Jinkwang’ was 62 cm, which was 13 cm shorter than that of ‘Jopyeong’. The panicle of ‘Jinkwang’ was composed of 100 spikelets. The viviparous germination rate of ‘Jinkwang’ was 28.3%. ‘Jinkwang’ showed resistance to blast and bacterial blight (K1, K2, and K3 races); however, it was susceptible to stripe virus, dwarf and black-streaked dwarf viruses, and plant hoppers. The milled rice grains of ‘Jinkwang’ showed an excellent palatability index (0.42) and lower protein content (6.2%) than that of ‘Jopyeong’. The grain milling characteristics were better than those of ‘Jopyeong’, especially in terms of brown/rough rice ratio and milled/rough rice ratio (75.9%). ‘Jinkwang’ showed a milled rice productivity of 5.91 MT/ha at eight sites under ordinary cultivation conditions. (Registration No. 7318).

‘Hwawang’ is an early maturing and short statured rice cultivar adaptable to the rice–cash crop rotation system that was developed by the rice breeding team of the Department of Southern Crop, National Institute of Crop Science (NICS), Rural Development Administration (RDA), Korea, in 2012. This cultivar was derived from the cross of YR25867 (Hitomebore//YR21247-B-B-B-49-1/Sasanishiki BL4) and YR25866 (Akidagomachi//YR21247-B-B-B-49-1/Sasanishiki BL4) during the 2005/2006 winter season and was fixed as a homozygous line by a doubled haploid breeding system. In the replicated yield trial in 2009, a promising line (YR26253Acp26-1) showed a good phenotype and high yield potential, and so it was selected and designated as ‘Milyang256’. The local adaptability test of ‘Milyang256’ was carried out at three locations from 2010 to 2012. It was named ‘Hwawang’ and had a high head rice ratio and good eating quality. The culm length of ‘Hwawang’ averaged 62 cm during the yield trials and was 10 cm shorter than that of ‘Keumo’. The number of spikelets per panicle of ‘Hwawang’ was significantly lower than that of ‘Keumo’, but the number of tillers per hill was higher. This variety showed resistance to bacterial blight disease but was moderately susceptible to both leaf and neck blast. The milled rice yield of ‘Hwawang’ was 452 kg/10 a at the late transplanting stage of the local adaptability test. Thus, ‘Hwawang’ is well adapted to the rice–cash crop rotation system in the southern plain area. (Registration No. 5106)

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).

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.

‘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.

The ‘Jungmo1023’ is the japonica rice variety developed from a cross between Yeongdeog34 and F1 of Iksan456 and SR21097-B-B-19-2-2 by the rice breeding team at NICS in 2012. The heading date of ‘Jungmo1023’ is August 3 in middle plain area and it is six days earlier than ‘Hwaseong’. ‘Jungmo1023’ has 80 cm of culm length which is 4 cm shorter than those of ‘Hwaseong’ and 107 spikelet per panicle. The premature heading rate of ‘Jungmo1023’ was 3.3%. It showed resistance to blast, bacterial blight (K1, K2, K3 race) and stripe virus, but susceptibility to K3a race of bacterial blight, dwarf and black streak dwarf viruses and planthoppers. The milled rice of this variety exhibits translucent and medium short grain shape. It has better palatability index of cooked rice (0.24) and lower amylose content (18.0%) 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 (96.2%). ‘Jungmo1023’ showed 4.56 MT/ha of milled rice productivity at 7 sites in ordinary cultivation. However, ‘Jungmo1023’ showed early cultivation culture adaptability because of 98% of its yield potential (4.99 MT/ha) compared to high yielding early-maturing variety ‘Jopyeong’. ‘Jungmo1023’ could be adaptable to the middle plain, mid-mountainous and north-east coastal area in Korea (Registration No. 5115).

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.

‘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.