The grain size and shape have a significant impact on the grain quality and yield of rice. Additionally, due to the globalization of the rice market, there is a demand for rice varieties of various sizes. In this study, we analyzed quantitative trait loci (QTL) associated with grain length (GL), grain width (GW), grain thickness (GT) and ratio of length-to-width (RLW) using 149 F₂ plants obtained from a cross between Hopum and Basmati 370. To construct a linkage map, we utilized 89 Fluidigm SNP markers, which covered a span of 1,116 cM of F₂ population. Nine QTLs associated with four traits were identified on chromosomes 2, 3, 5, and 7. One major QTL on chromosome 3 accounted for 43.2% of the phenotypic variation in GL. Additionally, QTLs named qGW2 and qGW5 on chromosomes 2 and 5 were detected for GW, explaining 10.4% and 18.6% of the phenotypic variation, respectively. Three QTLs for GT were found on chromosomes 2, 5, and 7, explaining 9.9%, 12.9%, and 9.9% of phenotypic variation, respectively. These QTLs offer potential applications in breeding programs using Basmati 370 to develop long and slender grain japonica varieties.

‘Superhongmi’, a reddish brown rice cultivar, was derived from a cross between CG2-3-5-1-6-1 (Heugjinju/Suwon 425) producing blackish purple rice and ‘Daeribbyeo 1’ producing large white grains. A promising line, SR28721-7-5-2-1-2-1, was obtained using the pedigree breeding method from 2003 to 2015 and designated as ‘KNOU6R’. This variety headed on September 5, and its culm length is 94.7 cm. The panicle length of ‘Superhongmi’ is 19.8 cm. The number of panicles per hill and grain per panicle is 5.4 ea and 154.9 ea, respectively. The fertility ratio of ‘Superhongmi’ is approximately 91.0% and 1000-grain weight (TGW) is approximately 26.8 g, which is similar to that of ‘Superjami’; however, the number of panicles per hill is half of that of ‘Superjami’. The content of taxifolin and total polyphenol extracted from whole grains of ‘Superhongmi’ is 67.7 and 248 mg/100g seed weight, respectively (Registration No. 7365).

‘Hyowon 3’, a medium-maturing glutinous rice variety was developed by the rice breeding team of Pusan National University in 2013. This cultivar was developed from a cross between ‘Hongna’ which is a landrace from the Korean peninsula showing good glutinous properties, and ‘Junam’, which has stable productivity. During the F₃–F₈ generations, breeding lines were selected using a pedigree breeding method. As a result, the promising line (JS24-6-95-11-5-2-1-1-1-B) with good glutinous properties was advanced and designated as ‘SP 107’. This variety headed on Aug. 16, which is 3 days later than ‘Dongjinchal’ in the middle plane. The average culm length and panicle length of this variety were 80.7 cm and 20.1 cm, respectively. This variety yielded approximately 14.1 tillers per hill and 104 spikelets per panicle. The ratio of ripened grain was about 93.0%, and the 1,000-grain weight was 19.30 g in brown rice. The yield performance was 492 kg/10a in a local adaptability test.

Hyowon6, a mid-late maturing, good eating quality rice variety with multi-resistance, was developed by the rice breeding team of Pusan National University in 2013. This variety was derived from a cross between Hwayeong (as a multi-resistant parent) and Koshihikari (as a good eating quality parent). Selection by the pedigree breeding method was carried out until the F₈ generation. A promising line, JS14-12-36-8-5-3-1-1-1, was developed and designated as HY103 in 2013. This variety headed on August 22, which was 11 days later than that of Hwayeong. The culm length and panicle length of Hyowon6 was 85.7 cm and 21.1 cm, respectively. The number of panicles per hill was 14.5 and the number of grains per panicle was 101.7. The ratio of ripened grain was approximately 92% and the 1,000-grain weight was approximately 21.36 g for brown rice, which were similar to those of Hwayeong. Hyowon6 was moderately resistant to lodging and also to neck blast, leaf blight, and stripe virus. The glossiness value of Hyowon6 was 83, which was considerably higher than that of Hwayeong.

‘Hyowon 4’, a new medium maturing glutinous rice variety was developed by the rice breeding team of Pusan National University in 2013. This cultivar was derived from a cross between ‘Boseokchal’ and ‘Donna’ with good glutinous property. During F3~F8 generation, breeding lines were selected by a pedigree breeding method. As a result, the promising line (JS23-4-39-14-5-1-1-1) with good glutinous property was advanced and designated as the name of ‘SP 106’ in 2012. This variety headed on Aug. 15, which is 2 days later than ‘Dongjinchal’ in middle plane. The culm length and panicle length of this variety was 82.4 cm and 21.1 cm, respectively. This variety has about 13.9 tillers per a hill and 100 spikelets per a panicle. The ratio of ripened grain is about 92.0% and 1000-grain weight was 20.9 g in brown rice. The yield performance was 5.03 MT/ha in local adaptability test.

'Hyowon 2’, a new medium-late maturing glutinous rice variety with short clum and lodging tolerance was developed by the rice breeding team of Pusan National University in 2013. This cultivar was derived from a cross between 'Junam’ as a short clum source and ‘Donna’ with a good glutinous properties. During selected by the pedigree breeding method, until F8 generation. As a result, a promising line, JS22-3-24-1-6-2-1-1-1, was advanced and designated as the name of ‘SP 105’ in 2012. This variety headed on Aug. 22 is 9 days later than ‘Dongjinchal’ in middle plane. The Culm length and panicle length of this variety was 65.6 cm and 22.5 cm, respectively. This variety has about 14.4 tillers per hill and 113 spikelet numbers per panicle. The ratio of ripened grain is about 93.0% and 1000-grain weight was 18.4 g in brown rice. This variety has higher α-tocotrienol content compared to that of ‘Hwasunchal’. The yield performance of brown rice was 4.81 MT/ha in local adaptability test.