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).

‘Dabokchal, a glutinous rice variety (Oryza sativa L.) with a medium late maturation period was developed by the Department of Crops and Food, JARES in 2020. It was derived from a cross between the glutinous cultivar ‘Shinmyeongheugchal’ with the good glutinous properties and ‘Hwangkumnodeul’ as a high yielding source. The progenies of the cross were selected by bulk and pedigree breeding method until the F₈ generation. As a result, a promising line, JR53-28-4-10-5-3, was advanced and designated as the name of ‘Jeonbuk12’ in 2018. The ‘Jeonbuk12’ local adaptability test was carried out at four locations during 3 years from 2018 to 2020. This variety headed on August 13, which was eight days later than ‘Sinseonchal’ in Honam plane. The culm and panicle length of this variety was 70 cm and 22 cm, respectively. This variety has about 16 tillers per hill and 92 spikelets per panicle. The ratio of ripened grain is approximately 84.9% and 1000-grain weight was 24.9 g in brown rice. This variety has a higher amylose content compared to that of ‘Sinseonchal’. The yield performance of brown rice was 591 kg/10a in the local adaptability test. This cultivar is considered to be adaptable to the Honam plain area of Korea (Registration No. 9602).

The cultivated area of glutinous rice in the Homan Plain of Korea is increasing to diversify the cropping system. Depending on the time of transplanting, glutinous rice can be divided into early, ordinary, and late cultivation. Eight glutinous rice cultivars (Baegseolchal, Baekogchal, Boramchal, Boseogchal, Dongjinchal, JJ644wx, Nunbora, and Sinseonchal) were used to evaluate yield, pasting properties, and texture according to cultivation time and to analyze the genotype-environment relationship. There were nine yield-related, six pasting-related, and four texture-related traits studied. Heading date and culm length were shortened as cultivation time increased, while panicle length, number of spikelets, and 1,000-grain weight increased. Furthermore, late cultivation time also reduced pasting properties, peak viscosity, trough viscosity, and final viscosity. Hardness and adhesiveness among the texture properties increased with cultivation time, but stickiness decreased. The variation in 1,000-grain weight is mostly dominated by genotype, whereas heading date and yield are heavily influenced by environmental factors. All pasting property characteristics varied with environment changes, and genotype variation was dominant for all texture properties. Boramchal yielded the most in early and ordinary cultivation and Sinseonchal, together with Boramchal, yielded the most in late cultivation. Cultivars with excellent grain quality were Sinseonchal in early cultivation and Baegseolchal and Baekogchal in ordinary and late cultivation. A comparative analysis of characteristics based on cultivation time can assist in the selection of glutinous rice suitable for the Honam Plain and in the breeding of cultivars with improved yield and excellent grain quality.

‘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.

‘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.

This study was conducted to analyze the starch and pasting properties of fourteen glutinous rice varieties with different maturity, and we compared the textural characteristic difference in relation to stickiness of glutinous rice cake. The whiteness values of grain appearance showed significantly differences in the order of early < medium < mid-late maturing glutinous rice varieties. Early maturing glutinous rice varieties exhibited a little high tendency for crude protein content than that of other varieties. Mid-late glutinous rice varieties showed higher of short chain ratio of 6 to 12 in DP of amylopectin whereas, medium length chains of 13 to 24 were significantly low. According to Rapid Visco-Analyzer measurement glutinous rice flours and starches, peak time showed high negative correlation with short chains of 6 to 12 in DP. The hardness of mid-late maturing glutinous rice cake was distinctly lower than that of the other glutinous rice varieties. Furthermore, mid-late maturing glutinous rice varieties, Baegseolchal, Dongjinchal and Baekogchal tend to show lower and slower in hardness changes of rice cake during storage. The hardness changes of glutinous rice cake had positive correlation with the amylose content and peak time and negative correlation with short chains of 6 to 12 in DP of amylopectin, respectively.