• KOREAN JOURNAL OF CROP SCIENCE
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• v.66 no.4
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• pp.279-288
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• 2021

Low-density transplanting is a cultivation technology that reduces labor and production costs. In this study, the growth and yield of several varieties with different tillering characteristics were analyzed in order to establish an appropriate planting density for low-density transplanting. Varieties with Low-Tillering (LT), Medium-Tillering (MT), and High-Tillering (HT) were planted at a density of 37-80 hills/3.3 m². As the planting density decreased, the number of tillers per hill increased, but the number of tillers per square meter of hill decreased, especially for the LT variety. Decreasing density extended the tillering stage, which was longest in the LT variety. As the planting density decreased, SPAD(Soil plant analysis development, chlorophyll meter) values just before heading increased while canopy light interception decreased. Such changes were much greater in the LT variety than in the MT and HT varieties. The heading date tended to be delayed by 0-2 days as the planting density decreased, and there was no difference in the length of the period from first heading to full heading. As the number of spikelets per panicle increased, the number of spikelets per square meter did not differ according to the planting density. Decreasing planting density did not affect the grain weight; nevertheless, the yield ultimately decreased because of the decreasing ripening rate. The optimal planting density for stable low-density transplanting cultivation was determined to be over 50 hills/3.3 m2. In addition, these results suggest that LT varieties should be avoided, since these showed large decreases in growth and yield with decreasing planting density.

• Korean Journal of Breeding Science
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• v.51 no.1
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• pp.34-40
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• 2019

'Jungmo1033', a japonica rice variety, was developed by the rice breeding team at the National Institute of Crop Science (NICS) in 1992. It is derived from a cross between a native variety 'Jagwangdo', which has translucent milled rice and medium maturity; and 'Hwayeong', which is an elite line with bacterial blight resistance and mid-late maturity. The heading date of 'Jungmo1033' was August 10 in the middle plain area of Korea, which was two days later than that of 'Hwaseong'. 'Jungmo1033' has a culm length of 79 cm, which was 5 cm shorter than that of 'Hwaseong', and 105 spikelets per panicle. 'Jungmo1033' showed resistance to bacterial blight (K1, K2, and K3 races) and stripe virus, but susceptibility to the K3a race of bacterial blight, dwarf and black-streaked dwarf viruses, and planthoppers. The milled rice of this variety exhibited translucency and a medium short grain shape. It had an excellent appearance and lower amylose content (19.1%) than that of 'Hwaseong'. The characteristics related to grain milling were better than those of 'Hwaseong', especially head rice milling recovery ratio and head rice ratio (94.8%). 'Jungmo1033' showed a milled rice productivity of 5.38 MT/ha at 11 sites under ordinary cultivation conditions. (Registration No. 5723)

• Korean Journal of Breeding Science
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• v.51 no.4
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• pp.448-453
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• 2019

'Haedamssal' is an early maturing and rice stripe virus disease-resistant cultivar adaptable for early-transplanting cultivation that was developed by the rice breeding team of the Department of Southern Crop, NICS, RDA, in 2014. This cultivar was derived from the cross YR25869 (YR21247-B-B-B-49-1/Sasanishiki BL4//Koshihikari) and YR25868 (Unkwang//YR21247-B-B-B-49-1/Sasanishiki BL4) made in the 2005/2006 winter season and was advanced to the F₅ generation by a bulk breeding method using rapid generation advance. To incorporate rice stripe virus resistance, marker-assisted selection on the RSV gene was conducted in 3-way and 6-way cross F₁ generation using the tightly linked marker RM6897. From testing in the replicated yield trial in 2011, a promising line YR26258-B-B-B-33-3 was selected and it was designated as 'Milyang276'. A local adaptability test of 'Milyang276' was performed at three locations from 2012 to 2014 and it was named as 'Haedamssal', which was a good eating quality variety. The culm length was 67 cm in yield trials, which was 4 cm shorter than 'Jopyeong'. The number of spikelets per panicle was lower than 'Jopyeong', whereas the number of tillers per hill was higher. This variety was resistant to RSV disease, bacterial blight, and leaf blast disease. The milled rice yield of 'Haedamssal' was 5.48 MT per ha at the early transplanting in the local adaptability test. 'Haedamssal' is well adapted to early transplanting cultivation in the southern plain area (Registration No. 6811).

• Journal of the Korean Society of International Agriculture
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• v.31 no.1
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• pp.76-81
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• 2019

'Asemi' is a rice variety derived from a cross between 'Jinmibyeo' which has translucent milled rice and medium maturity and 'Cheolwon46', an elite line with high yield and early maturity by the rice breeding team at NICS, RDA in 2013. The heading date of 'Asemi' is August 1, six days earlier than the check variety 'Hwaseong'. It has 82 cm culm length and 109 spikelets per panicle. 'Asemi' is resistant to blast disease, stripe virus and tungro virus, but susceptible to other viruses and planthoppers. The milled rice of this variety exhibits translucent, clear non-glutinous endosperm and short grain shape. It has protein content (6.7%) higher than 'Hwaseong', and amylose content (19.5%) similar to 'Hwaseong'. The milled rice recovery rate of 'Asemi' is similar to that of 'Hwaseong'. However, the head rice rate of 'Asemi' is higher than that of 'Hwaseong'. Milled rice yield of 'Asemi' is 5.23 MT/ha in ordinary cultivation. ' Asemi' could be adaptable to the wide region of tropical Asia (Registration No. 5639).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.4
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• pp.276-284
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• 2023

Nitrogen is a major and essential macronutrient for plant growth and development. However, excessive nitrogen application can lead to ecological pollution or greenhouse gas emissions, consequently resulting in climate change. In this study, we used 153 genetic resources of rice to evaluate the effects of the levels of nitrogen application on grain yield and yield-related traits. Significant differences were noted in the yield and yield-related traits of genetic resources between two nitrogen application levels, namely, 4.5 kg/10a (NN: normal nitrogen condition) and 9.0 kg/10a (LN: low-nitrogen condition). Among the tested traits, days to heading (DTH), clum length (CL), grain yield per plant (GYP), number of panicles per plant (NPP), and number of spikelets per panicle (NSP) decreased by 1.8 to 17.9% when the nitrogen application levels decreased from NN to LN. The 1,000-grain weight (TWG) and percentage of ripened grain (PRG) increased by 2.6 to 11.2% under these conditions. Based on nitrogen application levels, two-way analysis of variance (ANOVA) demonstrated significant differences in GYP, NPP, and PRG but not in NSP and TGW. NPP exhibited negative correlations with NSP (-0.44) and TGW (-0.44), and TGW displayed a negative correlation with PRG (-0.34), whereas, GYP exhibited a positive correlation with PRG (0.37) and NSP (0.38). A similar pattern was recorded under the LN condition. NPP, TGW, and PRG were clustered as PA (principle axis) 1 under the LN condition by factor analysis. NSP and GYP were clustered as PA (principle axis) 2. These results demonstrated NPP and NSP as the primary factors contributing to the decrease in grain yield under LN conditions. In conclusion, we selected eight genetic resources that exhibited higher GYP under both NN and LN conditions with higher NPP or NSP. These genetic resources can be considered valuable breeding materials for the adaptation of plants to nitrogen deficiency.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.654-659
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• 2009

"Cheongcheongjinmi" is a new japonica rice variety developed from a cross between Iri401 and Ilpumbyeo by the rice breeding team of National Institute of Crop Science, RDA. This variety is suitable for ordinary season culture of low level nitrogen application. Heading date of "Cheongcheongjinmi" is August 17, 4 days later than that of Sobibyeo in plain areas. It has culm length of 82 cm, and relatively semi-erect pubescent leaf blade and slightly tough culm tolerant to lodging with good canopy architecture. This variety has 13 tillers per hill, 126 spikelets per panicle and 90.2% of ripened grains. "Cheongcheongjinmi" showed lower spikelet fertility than Sobibyeo when exposed to cold stress. This variety showed slower leaf senescence and lower viviparous germination compared to Sobibyeo during the ripening stage. "Cheongcheongjinmi" is susceptible to blast disease, bacterial blight, virus diseases and planthoppers. The dried plant weight, total nitrogen and RuBisCO activity of "Cheongcheongjinmi" were higher than those of Sobibyeo in low level nitrogen application. The milled rice of "Cheongcheongjinmi" exhibits translucent, clear non-glutinous endosperm and medium short grain. It shows lower protein and amylose contents than those of Sobibyeo, and better palatability of cooked rice compared to Hwaseongbyeo. The milled rice yield of this cultivar is about 5.10 MT/ha at low level nitrogen application of ordinary season culture in local adaptability test for three years. Especially, "Cheongcheongjinmi" has better milling properties such as the percentage of whole grain in milled rice and milling recovery of whole grain, respectively than those of Sobibyeo. "Cheongcheongjinmi" would be adaptable to middle plain areas and middle-western coastal areas of Korea.