중만생 저아밀로스 다수성 벼 ‘정다미’

Abstract

“Jeongdami” is a specialized rice (Oryza sativa L.) variety developed to enhance the competitiveness of regional branded rice through its distinct characteristics, setting it apart from those from other regions. It is an early-maturing, semi-dwarf variety with strong resistance to rice blast and features intermediate stickiness with a low amylose content (11.6%), using “Wolbaek” as the maternal parent. The paternal parent is an F1 hybrid created by crossing the large-grain, intermediate-maturity glutinous rice variety “Nunbora,” which is resistant to bacterial blight (K1, K2, and K3), with “Boramchan,” a high-yield, medium-late Japonica variety that is resistant to bacterial blight (K1, K2, and K3) and stripe virus. The breeding process culminated in 2020, resulting in “Jeongdami.”. Key agricultural characteristics include an average heading date of August 15, which is 6 days earlier than “Baekjinju”, an important low amylose mid-late cultivar, making it a medium-late variety when grown in the four plains regions in the central plains of Korea. Its culm length is moderately short at 77 cm, with an average of 16 panicles per hill and 96 spikelets per panicle. The 1,000-grain weight of brown rice is 20.0 g, similar to that of “Baekjinju.” There was no premature heading, leaf senescence at maturity was moderate, and the pre-harvest germination rate was 1.7%, lower than that of “Baekjinju” (7.5%). The overall cold tolerance rating was 7, indicating weak tolerance similar to “Baekjinju;” however, the variety showed strong lodging resistance in the field. “Jeongdami” exhibited strong resistance to bacterial blight (K1, K2, and K3) and moderate resistance to leaf blast but showed susceptibility to stripe virus, brown planthopper, and white-backed planthopper. The average polished rice yield was 547 kg per 10a, a 16% increase compared to that of “Baekjinju” (472 kg). The grain shape, with a paddy grain length-to-width ratio of 2.2 and a brown rice length-to-width ratio of 1.8, was similar to that of “Baekjinju,” maintaining a short and round shape. The endosperm is clearer than that of “Baekjinju,” providing superior visual quality. The protein content was 6.2%, and the amylose content was 11.5%, indicating intermediate stickiness, which was attributed to the Wx-mq gene. Due to its soft texture and stable cultivation, “Jeongdami” will contribute to increasing rice consumption by enhancing the competitiveness of regionally branded rice with its excellent eating quality and cultivation stability. (Grant No. 9168).