To improve resistance to planthoppers and viral diseases, a new rice cultivar named ‘Drimi9ho’ was established. The F₁ population, derived from a cross between ‘Cheongcheong’ and ‘Nagdong’, was subjected to anther culture. Subsequent generations were advanced in the field under high selection pressure for agronomic traits and disease resistance. Ultimately, the line ‘CNDH-AC63-2-2-2-1’ was selected through the pedigree method and was named ‘Drimi9ho’ after undergoing yield trials and local adaptability tests. ‘Drimi9ho’ has a heading date of August 13, which corresponds to 107 days after sowing, making it a mid-late maturing variety that heads 3 d later than ‘Cheongcheong’. The culm length of ‘Drimi9ho’ is 57.3 cm, which is 15 cm shorter than that of ‘Cheongcheong’. This reduced culm length contributes to improved tolerance to field lodging. In addition, ‘Drimi9ho’ exhibits acquired resistance to rice black-streaked dwarf virus through introgression from ‘Nagdong’. Compared to ‘Cheongcheong’, ‘Drimi9ho’ shows lower protein content and higher amylose content, which resulted in a higher score for cooked-rice palatability. ‘Drimi9ho’ shows improved milling performance compared to ‘Cheongcheong’. The 1,000-grain weight of ‘Drimi9ho’ is 22.12±0.8 g, which is heavier than that of ‘Cheongcheong’ (19.42±0.8 g). The milled rice yield of ‘Drimi9ho’ is 546.6±3.8 kg/10a, representing a 4.7% increase compared to ‘Cheongcheong’ (522.2±5.8 kg/10a). However, ‘Drimi9ho’ is resistant only to bacterial leaf blight race K₁; thus, timely disease management is required to control other races such as K₂, K₃, and K_3a (Registration No. 10610).

Rice is an important food crop that feeds most of the world's population. However, due to the increased frequency of pest outbreaks, it is necessary to cultivate complex pest-resistant rice cultivars. A mutant population was derived by culturing tissue of ‘Hwayeong’ at the Plant Molecular Breeding laboratory of Kyungpook National University in the Republic of Korea. The cultivar ‘Drimi4ho’, a line that was resistant to complex disease, was finally selected by backcrossing with ‘Junam’. The heading date of ‘Drimi4ho’ is August 11 (107 days after sowing). Drimi4ho’ has culm length of 69 cm, panicle length of 21 cm, 16 panicles per hill, 115 spikelets per panicle, a ratio of ripened grain of 92.7%, and a 1,000-grain weight of 24.3 g. No lodging occurred when ‘Drimi4ho’ was grown in the field by standard fertilization. It is also resistant to leaf/neck blast disease, bacterial blight (K₁, K₂, K₃), rice dwarf virus, rice black-streaked dwarf virus, rice stripe virus, BPH, and SBPH. ‘Drimi4ho’ is a round and short-type grain, and is very clear and transparent without chalkiness. In addition, it has excellent physicochemical properties that make up food, so its taste is good. When ‘Drimi4ho’ was planted under ordinary conditions in the southern mountainous area of Korea, the yield was 5.53 MT/ha (Registration No. 6124).

Rice is a staple food in most countries, and thus, diversifying its value is necessary. Recently, the focus on good health has increased, and rice cultivars with improved properties should be bred based on consumer demands. At the Plant Molecular Breeding Laboratory of Kyungpook National University, “Hwayeong” was tissue-cultured to derive mutant populations. In the mutant lines, “P35” with high protein content and excellent agricultural traits, was backcrossed with “Ilmi” three times, and the final selected line was called “Drimi5ho.” The heading date of “Drimi5ho” was August 11 (107 d after sowing), which was 5 d later than that of “Ilmi” (August 5, 101 d after sowing). The culm length of “Drimi5ho” was 71 cm, the panicle length was 18 cm, the number of panicles per hill was 13, the number of spikelets per panicle was 113, the ratio of ripened grain was 90.5%, and the 1,000-grain weight was 22.6 g. When "Drimi5ho" was planted ordinary plantation, the yield in the southern mountainous area was 526 kg/10a. Lodging was not observed when “Drimi5ho” was grown in the field with standard fertilization (N-P₂O₅-K₂O = 9-4.5-5.7 kg/10a). This rice cultivar was resistant to leaf/neck blast, bacterial blight (K₁, K₂, and K₃), rice stripe virus, rice black-streaked dwarf virus, and rice dwarf virus. The milled grain of “Drimi5ho” was clear and transparent without any chalkiness; moreover, the grain shape was round and short. Although it is a specialty rice with increased protein content, the taste of the rice and the grain quality were excellent (Registration No. 6829).

Rice is one of the most important food crops in the world, but brown planthopper (BPH, Nilaparvata lugens stal) causes a significant loss of rice yield. Due to climate change, different races of rice-damaging species are evolving at an accelerated pace, thus, creating a need to breed multi-resistant rice cultivars for a stable food supply. In 2001, “Samgang” and “Nagdong” were crossed at the Plant Molecular Breeding Laboratory of the Department of Applied Biosciences, Graduate School, Kyungpook National University, Daegu Korea. “Drimi3ho” is a resistant and high-quality rice cultivar that was bred by backcrossing a line having excellent agronomic traits with “Ilmi.” The heading date of “Drimi3ho” was August 12 (104 d after sowing), and it was a medium-maturing cultivar that matured 3 d earlier than “Ilmi” (August 15, 107 d after sowing). Its culm length was 81 cm, panicle length was 18 cm, panicle number per hill was 16, spikelet number per panicle was 113, ripened grain ratio was 93.2%, and 1,000-grain weight was 24.3 g. “Drimi3ho” was highly resistant to blast disease and bacterial blight (K₁, K₂, and K₃), rice stripe virus, rice dwarf virus, rice black-streaked dwarf virus, and BPH. When “Drimi3ho” was milled, the milled grain was clear and transparent; moreover, the grains were semi-round and short-type. Moreover, “Drimi3ho” had lower protein and amylose content and tasted better than “Ilmi.” When “Drimi3ho” was grown on an ordinary plantation in the southern mountainous area, the yield was 563 kg/10a (Registration No. 5621).

Rice is an important crop used as a staple food in most of the world; however the occurrence of pests is increasing due to climate change. In particular, the brown planthopper (BPH, Nilaparvata lugens stal) is a key cause of rice yield loss. In response to the era of unpredictable climate change in the future, the Plant Molecular Breeding laboratory of the Department of Applied Biosciences, Graduate School, Kyungpook National University, Daegu 41566, Korea bred the ‘Drimi2ho’ strain, which is resistance to BPH or various pests and of excellent eating quality. In order to cultivate ‘Drimi2ho’, ‘Samgang’ and ‘Nagdong’ were crossed and the derived seeds were backcrossed with ‘Junam’, and the pedigree breeding method was applied. During the application of the pedigree method, agricultural characteristics which are investigated in the field were found to be excellent, and the best line for various disease resistance, grain quality, and yield was finally selected as ‘Drimi2ho’. ‘Drimi2ho’ has strong resistance to BPH and its range of resistance to major pests and viral diseases such as blast and bacterial blight on rice is quite wide. In the field, the main agricultural characteristics of ‘Drimi2ho’ were similar to or improved from those of ‘Junam’. ‘Drimi2ho’ is a cultivar with enhanced disease and pest resistance and a wide spectrum while maintaining the good eating quality. ‘Drimi2ho’ yielded 584 kg/10a in ordinary cultivation under normal level of fertilization in south mid-mountainous areas of Korea. Drimi2ho’ can thus be a standard cultivar in Korea due to its varied resistance to multiple diseases and excellent grain quality. (Registration No. 4686).

Brown planthopper (BPH, Nilaparvata lugens Stal) is a major agricultural pest that plays a key role in reducing rice yield. Rapid climate change has emphasized the necessity of cultivating multi-resistant cultivar rather than cultivar with single-resistance to specific pests. Accordingly, the Plant Molecular Breeding Laboratory of the Department of Applied Biosciences, Graduate School, Kyungpook National University, Daegu 41566, Korea developed the ‘Drimi 1ho’ rice cultivar with enhanced resistance to blast and bacterial blight as well as BPH breeding in 2008. In order to breed ‘Drimi 1ho’, ‘Samgang’ and ‘Nagdong’ were crossed and backcrossed with ‘Junam’, after which the pedigree breeding method was applied. Finally, ‘Drimi 1ho’ was selected through analysis of resistance to insect and viral disease, yield, and grain quality. ‘Drimi1ho’ is strongly resistant to BPH and has a wide range of resistance to pests. ‘Drimi 1ho’ is also resistant to blast and bacterial blight (K₁, K₂, K₃), which occurs most frequently and causes serious damage to crops in the Republic of Korea. The agricultural characteristics of 'Drimi 1ho' were similar or improved from 'Junam'. In particular, ‘Junam’ is susceptible to BPH and bacterial blight. ‘Drimi 1ho’ made up for the shortcomings of ‘Junam’ with acquired strong and broad-spectrum resistance. Finally, ‘Drimi 1ho’ had a yield of 563 kg/10 a under normal cultivation and can thus be an adaptable cultivar in south mid-mountainous areas in the Republic of Korea (Registration No. 3685).