‘Hwaweon 6’ was developed from a cross between ‘Hwaseongbyeo’ and a wild species, Oryza minuta L. (Acc. No. 101154) based on marker-assisted selection and backcrossing. The recurrent parent ‘Hwaseongbyeo’ is a high grain quality cultivar with medium maturity. Hwaweon 6 is nearly isogenic to Hwaseongbyeo except a small O. minuta introgressed segment on chromosome 7 harboring genes related with spikelets per panicle. The preliminary and replicated yield trial was conducted at Chungnam National University and Chungcheongnamdo Agricultural Research & Extension (CARES), Yesan in 2009 and 2010. The local adaptability test was carried out by the National Seed Management Office (NSMO) in 2011 and 2012. This cultivar was registered to NSMO with a cultivar designated as Hwaweon 6. This cultivar averaged 80cm in culm length and has a medium growth duration. Milled rice of Hwaweon 6 is translucent and the grain quality traits are comparable to those of the recurrent parent. The average yield potential of Hwaweon 6 in grain was about 6.57 MT/ha at the ordinary fertilizer level for two years about 3.0% higher than that of Hwaseongbyeo due to an introgression of the quantitative trait locus (QTL) for spikelets per panicle (qSPP7) from O. minuta. This variety is comparable to Hwaseongbyeo in low temperature germinability and cold tolerance. The qSPP7 QTL would be useful in enhancing yield potential in rice breeding program.

‘Hwaweon 7’ was developed from a cross between the African upland cultivar, ‘Moroberekan’ and ‘Ilpumbyeo’ based on marker-aided backcross selection. The recurrent parent, Ilpumbyeo is a high grain quality cultivar with medium to late maturity. Hwaweon 7 is nearly isogenic to Ilpumbyeo except a small Moroberekan introgressed segment on chromosome 6 harboring genes related with spikelets per panicle and internode diameter. The preliminary and replicated yield trial was conducted at Chungnam National University and Chungcheongnamdo Agricultural Research & Extension (CARES), Yesan in 2010 and 2011. The local adaptability test was carried out by the National Seed Management Office (NSMO) in 2012 and 2013. This cultivar was registered to NSMO with a cultivar designated as “Hwaweon7”. This cultivar averaged 80cm in culm length and has a medium growth duration. Milled rice of “Hwaweon7” is translucent and the grain quality traits are comparable to those of the recurrent parent. The average yield potential of Hwaweon 7 in grain was about 6.48 MT/ha at the ordinary fertilizer level for two years about 5.1% higher than that of Ilpumbyeo due to increase in spikelets per panicle. This variety is tolerant to lodging and the tolerance is due to the APO1 gene controlling the base internode diameter on chromosome 6 introgressed from the donor parent, Moroberekan. The Apo1 gene would be useful in enhancing resistance to lodging in rice breeding program.

‘Hwaweon3’ was developed from an interspecific cross between Hwayeongbyeo and a wild species, Oryza rufipogon L. (W1944) based on marker-aided selection and backcrossing. The recurrent parent ‘Hwayeongbyeo’ is a high grain quality cultivar with medium-maturity. ‘Hwaweon3’ is nearly isogenic to Hwayeongbyeo except a small O. rufipogon introgression on chromosomes 1, 8 and 12 harboring the QTL gene for cold tolerance. The preliminary and replicated yield trial was conducted at Chungnam National University in 2006 and 2007. The local adaptability test was carried out by the National Seed Management Office (NSMO) in 2008 and 2009. This cultivar was registered to NSMO with a cultivar designated as ‘Hwaweon3’. This cultivar averaged 78 cm in culm length and has a medium growth duration. This variety is resistant to stripe virus as the recurrent parent, and moderately resistant to leaf blast disease with durable resistance. Milled rice of ‘Hwaweon3’ is translucent and the grain quality traits are comparable to those of the recurrent parent. it has low protein content. The yield potential of ‘Hwaweon3’ in grain is about 7.23 MT/ha at the ordinary fertilizer level comparable to that of Hwayeongbyeo. ‘Hwaweon3’ performed better than Hwayeongbyeo in cold tolerance-related trait in the cold water-irrigated plot in the Chuncheon sub-station. This is mainly due to the introgressed segment from O. rufipogon on chromosome 1 harboring pe1.2 for panicle exsertion. ‘Hwaweon3’ could be used as a bridging line to enhance cold tolerance of japonica breeding lines.