‘Jowoo’, an early maturing, high biomass yielding rice (Oryza sativa L.) cultivar with high feed value and multiple disease-insect resistance, was developed for winter forage crop-whole crop silage (WCS) rice double cropping. It was derived from a cross between a high biomass and multiple disease resistant line ‘Suweon519’ and an early flowering, high yielding Tong-il type variety ‘Gaya’ that harbored Bph3 and BPH26, conferring brown planthopper (Bph) broad resistance. This cultivar had a growth period of approximately 106 days from seeding to heading, 97 cm culm length, 24 cm panicle length, 12 panicles per hill, 120 spikelets per panicle, and 1,000-grain weight of 22.1 g as brown rice in the central plain region of Suwon. This early flowering rice variety was tolerant to premature germination and cold stresses, especially showed higher grain fertility than ‘Nokyang’ at a cold-water (17℃) irrigated screening nursery. Further, ‘Jowoo’ exhibited high lodging resistance in the yellowing ripening stage, an optimal period for harvest. In addition, ‘Jowoo’ was resistant to leaf and neck blast, bacterial blight (race K1, K2, K3, K3a), rice stripe virus, and small Bph and was also moderately resistant to Bph. Its average dry matter yield for three years reached 18.2 MT/ha, the highest among early flowering rice varieties and 19% higher than that of ‘Nokyang’. This cultivar had 72.2% total digestible nutrients, which is also higher than that of ‘Nokyang’. In the Korean peninsula, ‘Jowoo’ grows well in the central and southern plains and can be harvested 30 days after heading. This helps improve its feeding value and digestion rate in livestock (Grant No. 8133).

Flower bud differentiation by temperature and photoperiod was investigated in early-, medium-, and late-maturing cultivars of radish (Raphanus sativus L.). Flower bud differentiation was induced by only day-length extension treatment (18 hr light/day) in early - and medium-maturing cultivars. Therefore, the early- and medium-maturing cultivars of radish were advanced the time of the flowering by the 2 weeks low temperature duration with day-length extension (18 hr light/day). The vegetative growth of early- and medium-maturing cultivar was the best by only day-length extension (18 hr light/day). However, late-maturing cultivar was needed for the flower bud differentiation and optimal vegetative growth not only long-day but also low temperature during 4~6 weeks at least. Our results suggest the optimal condition for flower bud differentiation in the each early-, medium-, and late-maturing cultivars of radish, which will be useful to develop breeding materials of radish.

There are farmer’s demands to develop early-maturing cultivar in order to replace Odae variety to mid-northern inland plain and southern mountainous area of Korea. Saeodae was developed by the rice breeding team of Cheolwon Substation, National Institute of Crop Science (NICS), RDA in 2012. This cultivar was derived from the cross between Geuroobyeo and Suweon 472 in 2001 summer season, and selected by a promising line, SR27376-2-2-1-3, was selected and designated as the line of Cheolweon 81 in 2010. The local adaptability test of Cheolweon 81 was carried out at four locations from 2010 to 2012 and it was named as Saeodae. The heading date of Saeodae is July 25 in Cheolwon area, which is 2 days earlier than that of Odae. This variety has 66cm in culm length and 77 spikelets per panicle. Its 1,000 grain-weight of brown rice is 26.5 g, which is similar to that of Odae. Germination rate at low temperature of this variety is about 70%, and viviparous germination is 17.7%. Cold tolerance of this cultivar is still not good, just mediocre. It shows strong lodging resistance. And premature heading, occurrence of wilting during ripening stage, and leaf senescence at maturing are similar to those of Odae. This variety shows resistance to leaf blast disease, but susceptible to bacterial blight, virus disease and insect pest. This variety has translucent and clear milled rice kernel without white core and belly rice. The yield potential of Saeodae was about 5.26 MT/ha at ordinary fertilizer level in local adaptability test for three years. This variety would be adaptable to mid-northern inland plain and southern mountainous area of Korea.