To promote the expansion of rice consumption, we examined the nutritional components and qualities of five Tongil-type rice varieties. Regarding texture properties, ‘Dasan’ showed the highest viscosity at 0.43 kgf, whereas ‘Hanareum3’ displayed the lowest at 0.20 kgf. Regarding pasting properties, ‘Hanareum4’ exhibited the slowest aging speed of rice flour dough with a value of -42.34 RVU, and ‘Hanareum3’ had the slowest aging speed of cooked rice with a final viscosity of 258.62 RVU. Regarding proximate compositions, ‘Hanareum3’ had the highest crude ash content at 1.17 g/100 g, and ‘Hanareum2’ had the highest crude protein content at 8.39 g/100 g. Regarding amino acids, at 0.17–0.18%, ‘Dasan’ had a methionine content 0.13% lower than the other varieties. Regarding mineral contents, potassium, phosphorus, and magnesium contents were the highest in ‘Hanareum3’ at 263.08, 354.85, and 109.18 mg/100 g, respectively. ‘Dasan’ showed the highest contents of iron, manganese, and zinc, measured at 0.94, 2.17, and 1.43 mg/100 g, respectively. Of the 36 fatty acids measured, only 9 were confirmed. Myristic acid, linoleic acid, and alpha-linolenic acid were highest in ‘Hanareum3’ at 0.27, 9.91, and 0.48 mg/g, respectively. ‘Hanareum4’ had the highest levels of palmitic, stearic, and oleic acids, with contents of 6.69, 0.79, and 9.64 mg/g, respectively. Arachidic, eicosenoic, and lignoceric acids were detected at high levels in ‘Geumgang1,’ ‘Hanareum2,’ and ‘Dasan,’ with contents of 0.16, 0.13, and 0.3 mg/g, respectively.

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.

Temperate japonica is used as the parent for crossing in the breeding of new rice cultivars in Korea, and the grain shape of the developed lines or cultivars is a semi-round and medium-short grain length. To overcome the current low quantity of japonica cultivar germplasm and deterioration in quality caused by climate change, it is necessary to diversify the grain characteristics of japonica. Most of the United States (US) cultivars are classified as medium, long, extra-long, and half spindle- and spindle-shaped grains. The qSW5 allelotype, a major gene involved in grain width, is found in all US cultivars. In addition, the US cultivar ‘Saber’ has both qgl3 and GS3_B alleles, which have low allele frequencies among Korean rice cultivars, and ‘A020’ had gw8, an allele with a reduced grain width. The pasting properties and texture of medium-grain length and half-spindle-shaped cultivars were relatively similar to those of the Korean rice cultivar, but different from those of long-grain and long spindle-shaped cultivars. Therefore, grain shape is associated with pasting properties and texture traits. Among the rice cultivars in the US, tropical japonica belongs to the same japonica as the Korean rice cultivar; however, its grain shape is similar to that of indica. As grain shape is also related to grain quality, US cultivars can be used as a useful genetic resource for diversifying the grain characteristics of Korean japonica cultivars and breeding new cultivars.

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.