Ginseng (Panax ginseng) is a self-fertilized crop, and all ginseng cultivars developed until now have been bred by pure-line selection. Ginseng has few genetic variations and lacks diversity in genetic resources. To obtain genetic resources with useful traits, mutations must be artificially induced. In this study, indehiscent seeds from ginseng landrace were treated with 20 to 400 Gy of gamma rays for 24 hours to determine the optimal dose for mutation breeding. Results showed no significant differences in seed dehiscence rates among the 0 Gy (control) to 80 Gy groups. However, above 100 Gy, the dehiscence rate sharply decreased as the radiation dose increased. Seed development below 40 Gy was superior to that of control but declined rapidly above 60 Gy. The seedling survival rate decreased significantly at 60 Gy (less than 50% compared to that of the control), and most seeds did not survive above 100 Gy. We observed a significant reduction in the growth of seedlings irradiated above 60 Gy. The above results suggest that a suitable gamma-ray dose for inducing mutagenesis in indehiscent ginseng seeds is 40 Gy.

A dwarf mutant rice line was selected from an Ac/Ds insertion mutant population and named dwf1. The phenotype of F₁ and F₂ plants derived from a cross between dwf1 and Dongjin indicated that a single recessive gene is responsible for the mutant phenotype, and we named this gene dwf1. Resequencing of the dwf1 line and Dongjin (wild type) revealed 42,386 homozygous single nucleotide polymorphisms (SNPs) between dwf1 line and Dongjin. MutMap analysis was performed by sequencing a DNA pool prepared from 100 mutant type plants in the dwf1/Dongjin F₂ population, and it was found that the dwf1 gene was located in the 23 ~ 30 Mbp region on chromosome 4. In this region, we found a non-synonymous SNP in the Os04g0469800 gene, which was reported as D11 gene encoding a cytochrome P450 family protein involved in the biosynthesis of brassinosteroids (BRs). This SNP was regarded as the causative SNP for the dwf1 phenotype, and the dwf1 gene is a novel allele of D11. We performed mapping of the dwf1 gene with five SNP markers on chromosome 4 with 190 dwf1/Dongjin F₂ plants. The phenotype of F₂ plants was completely co-segregated with genotypes of the J10402 marker, which was developed based on the non-synonymous SNP in the D11 gene. These results will contribute to the study of the molecular biological functions of the D11 gene and BRs.

A speed-breeding system using photoperiod characteristics has recently been developed to reduce the entire growth period in wheat. In this study, the entire growth period of four Korean varieties was examined to investigate whether this speed-breeding system would be beneficial for our wheat breeding program. When four varieties were cultivated under a 22-hour light/2-hour dark cycle in a glasshouse, the number of days to heading of Jokyoung and Baekkang was 44 and 43, respectively, and the number for Keumgang and Joongmo2008 was more than 75. Around twelve seeds per plant were obtained from Jokyoung and Baekkang, and the seeds of these varieties completely germinated when harvested at 20 days after heading. These results suggest that this speed-breeding system can be a reliable method of reducing the growth period in Korean wheat breeding.

FT-IR spectroscopy, combined with multivariate analysis, was used to determine whether 67 different wild and rootstock peach accessions could be discriminated from each other. Genomic DNA was isolated from leaves, and the purified genomic DNA was analyzed by FT-IR spectroscopy in the spectral region from 1800 to 800 cm^-1. FT-IR spectra showed that typical spectral differences existed in the frequency regions of N-H stretching (amide I), C=O stretching vibrations (amide II), and PO₂⁻ ionized asymmetric and symmetric stretching. Principal component analysis (PCA) was able to discriminate three groups. The partial least squares discriminant analysis (PLS-DA) yielded more clear discrimination among the three groups of peach accessions. The FT-IR spectral differences might be directly related to subtle changes in the base functional group and backbone structures of genomic DNA. This technique could provide a research foundation for FT-IR spectral-based rapid diagnosis, selection, and discrimination of peach accessions for rootstock.

In order to investigate salt-tolerant sorghum germplasms that can grow in saline soil from newly reclaimed land, we measured a well-established germination rate, and growth characteristics including leaf number, height, and root length in salt-treatment conditions (0.3, 0.6, 0.8, and 1.2%) and untreated control. The highly salt-tolerant sorghum line was confirmed using PCA (principal component analysis) analysis and fuzzy comprehensive evaluation method. Germination rate gradually decreased at doses higher than 0.3%, but the germination rates reached about 70% in IT124115, IS1041, Dansusu4ho, and Dansusu2ho germplasms. At 0.6% salt-treatment condition, the germination rates ranged from 35% to 100%. Only seven germplasms (IT103274, IT101381, IT104110, Dansusu4ho, IS20740, IS22720, and IS27887) had germination rates exceeding 50% at 0.8% salt-treatment. At 1.2% salt-treatment IT124115, IT028385, and IS1041 withered. The total number of leaves decreased similarly for both germplasms at salt levels below 0.6%, and sweet sorghum leaf count was more susceptible than grain sorghum at doses higher than 0.8%. In addition, the height of both germplasms was severely reduced even at low salt concentrations, whereas grain sorghum exhibited a greater sensitivity to salinity stress in terms of root length, while sweet sorghum had longer roots at low concentrations when compared with the untreated control. PCA analysis and fuzzy comprehensive evaluation showed that 29 sorghum accessions could be divided into 3 groups based on the germination rate and morphological traits. Especially, sweet sorghum accessions showed a different pattern of PCA plot when compared with the grain sorghum, and salt tolerance could be divided into 5 groups using MFV in terms of their traits. Taken together, the results from this work will contribute to the development of domestic agriculture utilizing marginal land such as reclaimed land by selecting elite sorghum germplasms that have a high salt tolerance and capacity.

Kimchi cabbage (Chinese cabbage) is a very common Korean traditional vegetable, cultivated across 32,000 ha, which accounts for about 13% of the total vegetable cultivation area in Korea. Since 2010, frequent occurrences of extreme weather conditions caused a shortage of summer, winter, and autumn Kimchi cabbage. Therefore, the National Institute of Horticultural and Herbal Science (NIHHS) selected a haploid breeding method of microspore culture to develop inbred lines that show resistance under extremely low or high temperature for Kimchi cabbage production. ‘Wonkyo20051ho’ is a double-haploid (DH) inbred line developed using the microspore culture method. Eleven heat resistant parental plants were selected through summer cultivation of 37 resources collected in 2014. Microspore culture was efficient in regenerating four resources, from which 13 DH inbred lines were developed. After artificially inoculating ‘Seosan’ clubroot with low concentration inoculum, 7 inbred lines showing moderate resistance were selected. As a result of the autumn cultivation of 83 breeding plants, including 6 selected inbred lines, the ‘18-FH98’ inbred line forming tight heads with yellow inner leaf under low temperature was finally selected during the 2018 autumn field trial. The selected DH inbred line was named ‘Wonkyo20051ho’ and is expected to be a valuable breeding material possessing tolerance to low temperature and clubroot.

‘Danjami’ was developed in 2015 as a purple-fleshed sweetpotato variety with excellent palatability. It was derived from a cross between ‘Yeonjami’ with purple flesh and ‘Yeonhwangmi’ with good palatability. The storage roots of this variety are elliptical with purple skin, and light purple flesh. It is moderately resistant to fusarium wilt and resistant to root-knot nematode. The texture of the steamed storage root of ‘Danjami’ is slightly moist and more tender than that of ‘Sinjami’. Soluble solid content of steamed storage roots of ‘Danjami’ was 31.3 °Brix, which was 20.8% higher than that of ‘Sinjami’. The palatability of steamed storage roots of ‘Danjami’ was better than that of ‘Sinjami’. The anthocyanin content of storage roots of ‘Danjami’ was 55.1 mg/100g dry weight. Total polyphenol content and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity did not differ from that of ‘Sinjami’. The number of marketable storage roots per plant and the average weight of marketable storage root was 2.8 and 136 g under the normal and late-season culture in ‘Danjami’, respectively. The marketable storage root yield of ‘Danjami’ was 21.5 MT/ha under the normal and late-season culture, which was 78.8% of that of ‘Sinjami’. The yield of marketable storage root over 50 g of ‘Danjami’ was 15.3 MT/ha under the early-season culture, which was 28.8% lower than that under the normal and late-season culture. ‘Danjami’ was more suitable for the normal and late-season culture than for the early-season culture (Registration No. 6465).

Limitation of genetic diversity in japonica rice breeding populations is often identified as a potential obstacle for the development of high yielding cultivars. The use of diverse germplasm in rice breeding has been suggested as one way of combating this problem. This study was conducted to improve the genetic diversity for rice, by developing an advanced backcross population derived from a backcross ‘Junam’ as recurrent parent and ‘IR72’ as a donor parent. Among them, we selected a promising line ‘YR24438-B-B-B-B-132’ containing bacterial blight resistance gene Xa4. Testing in the replicated yield trial in 2009, the ‘YR24438-B-B-B-B-132’ line was selected, and it was designated as ‘Milyang298’. The local adaptability test of ‘Milyang298’ was carried out at three locations from 2014 to 2016 and it was named ‘MY298BB’. The average culm length in the replicated yield trials was 87 cm, which is 15 cm taller than recurrent parent ‘Junam’. Number of spikelets per panicle was significantly lower than in ‘Junam’ but the number of tillers per hill was higher. This variety is resistant to bacterial blight race K1, K2, K3, and K3a.However ‘MY298BB’ showed early leaf senescence at the mature stage and the chlorophyll content of ‘MY298BB’ was significantly lower than that of the recurrent parent ‘Junam’. Moreover the grain filling ratio and yield were significantly lower in ‘MY298BB’ than those of recurrent parent ‘Junam’. Therefore, understanding the leaf senescence mechanism would be useful for improving yield potential in rice.

A new double cropping potato variety, ‘Geumseon,’ was bred by Highland Agriculture Research Institute, National Institute of Crop Science, Rural Development Administration in 2014. ‘Geumseon’ was obtained from the cross between ‘Chuyoung’ and ‘Daegwan1-87’ in 2005. The seedling and line selections of ‘Geumseon’ were performed from 2006 to 2007 and preliminary and advanced yield trials were carried out from 2008 to 2011 in Gangneung. The regional yield trials were conducted in three locations (Gangneung, Muan, and Jeju) from 2012 to 2014. ‘Geumseon’ has white flowers, green narrow leaflets and petioles, and short oval tubers with beige skin and white flesh. The dormancy of ‘Geumseon’ was 60-70 days in 20℃ after harvest, which is longer than those of ‘Dejima’ and ‘Chubaek’. The average yield of tubers in spring and fall were 42.1 and 25.8 ton ha^-1 in the regional yield trials, respectively. It is susceptible to common scab, late blight, and potato virus Y, but has a high resistance to potato leaf roll virus and potato virus X. The dry matter content was 21.9 and 23.0% in spring and fall season, respectively. Plant variety protection right of ‘Geumseon’ was registered in November 2018, and its grant number is 6924.

Sesame (Sesamum indicum L.) is a traditional oil seed crop grown in Korea. Sesame cultivation in Korea, however, is difficult and the yield is still very low. As such, a sesame variety, ‘Yoomi,’(Sesamum indicum L.) with disease resistance and high yield was developed in 2012. It was obtained by crossing ‘Yangbaek’ and SIG950480-6-3-1 in 2001. ‘Yoomi’ has few branches and a triple capsule per node. Notably ‘Yoomi’ exhibited a resistance to Phytophthora blight disease and a lodging resistance in the field. The yield of ‘Yoomi’ was about 1.06 ton per hectare, 8% higher than that of ‘Yangbaek’. ‘Yoomi’ crude fat content was 49.7%, and lignan content was 6.62 mg/g. This variety will contribute to increasing sesame production in Korea and will be utilized in sesame breeding programs.

The range of peach rootstocks currently available worldwide has increased dramatically in the last few decades. However, peach rootstocks in Republic of Korea still primarily use mainly seeds of different species imported from China. This kind of rootstocks is not ideal for clonal production and uniformity since it is a varietal blend of genotypes with differing physical characteristics. We collected genetic resources of 214 native peaches and determined 156 native peaches for breeding the suitable peach rootstock with easy propagation, uniform growth habit, and the resistance to biotic and abiotic stresses under domestic conditions. ‘PR1’ peach rootstock [Prunus persica (Batsch) L.] was originated from open-pollinated seeds of ‘PHJN0129’ collected in 2001 at Suncheon. ‘PR1’ peach rootstock was preliminarily designated as ‘PH193’ in 2002 and then grafted onto ‘Maotao’ (P. persica) wild peach seedling rootstocks. In Hwasung, three grafted trees were observed from 2005 to 2009 and seen to have the properties of ‘PH193’. In Suwon, one-year- old seedlings were observed from 2010 to 2014 and showed to have the commercial availability of ‘PH193’ when compared with 5 peach rootstocks (Tsukuba No.4, GF677, Nemaguard, Yumyeong, and imported peach seeds from China). ‘PH193’ was finally selected in 2014, owing to its superior seed germination, graft compatibility, resistance to nematodes and crown gall, and low mortality. It was named ‘PR1’ to indicate the first peach rootstock in Republic of Korea and was released for commercial use in 2015. (Grant Number 5896).

Baekgeumok, a sweet corn hybrid made by crossing inbred KSE15 and KSE21, was developed by the maize breeding team at the National Institute of Crop Science, Rural Development Administration in 2015. Baekgeumok silks at 63 days, similar to Danok3 (check variety). The plant height is 179 cm, higher than check variety, and the ear height is 105 cm, similar to check variety. Baekgeumok has an excellent lodging resistance. The fresh ear yields were 6,411 ears and 1,141 kg in 10 a. Pericarp thickness was 39 µm and sugar content was 19.5 °Bx. Sensory evaluation value was 6.1 and flavor was excellent. This hybrid can be cultivated in Gyeonggi-do, Gangwon-do, Chungcheongbuk-do, Gyeongsangbuk-do, and Gyeongsangnam-do. Seeds of Baekgeumok must be renewed annually, because this hybrid is a single cross hybrid. This sweet corn hybrid must be cultivated at least 200 m from areas with other corn varieties, because of their recessive gene. When cultivated at high density, the ear size and ratio of kernel set length / ear length will be lower in this hybrid than in standard cultivars. This hybrid requires pest control because it is susceptible to corn borer infestation. Drainage management is important in the rainy season. (Registration No. 6725)