다평옥은 다수성 종실용 옥수수 품종 개발을 위하여 2010 년에 농촌진흥청 국립식량과학원에서 자식계통 KS158과 KS155를 교잡하여 육성한 다수성 단교잡종이다. 다평옥의 종피색은 황색이며 입질은 마치종이다. 2006～2007년까지 2 년 동안 생산력검정시험을 거쳐 2008～2010년까지 3년 동안 수원 등 3지역에서 지역적응시험을 실시하였다. 그 결과 우수 성이 인정되어 2010 농작물 직무육성 신품종으로 결정되었고 다평옥으로 명명하였다. 다평옥의 출사일수는 장다옥과 같다. 간장은 장다옥과 비슷하며 착수고율은 장다옥과 같다. 도복은 장다옥 정도로 강한 것으로 나타났다. 이삭길이는 장다옥보다 다소 작으며 100립중은 장다옥보다 가볍다. 깨씨무늬병과 그 을음무늬병에는 강한 편이다. 검은줄오갈병, 이삭썩음병 및 조명나방 저항성은 중 정도를 보인다. 다평옥의 종실수량은 8.6 톤/ha로 장다옥보다 8% 많았다. 4 : 1(모본 : 부본) 재식 비율로 동시 파종하여 채종 시험한 결과 모본 출사기와 부본 화분비산기간이 일치하였으며 채종수량은 2.8 톤/ha이었다. 다평옥은 전국적으로 재배가 가능하다(품종출원등록번호: 제 4969호).

청다옥은 다수성 사료용 옥수수 품종 개발을 목표로 2010년에 농촌진흥청 국립식량과학원에서 자식계통 KS159과 KS155의 교잡으로 육성된 다수성인 단교잡종이다. 청다옥의 종피색은 황색이며 입질은 마치종이다. 2006～2007년까지 생산력검정시험을 거쳐, 2008～2010년까지 3년간 4지역에서 지역적응시험을 실시하였다. 청다옥의 출사일수는 광평옥보다 1일 빠르고 간장은 광평옥보다 다소 짧고 착수고율은 광평옥보다 낮다. 도복은 광평옥과 비슷한 정도로 강하다. 후기녹체성은 광평옥과 비슷하며 이삭비율은 광평옥과 같다. 깨씨무늬병 저항성은 중정도이고, 그을음무늬병에는 강한 편이다. 검은줄오갈병, 이삭썩음병 및 조명나방 저항성은 중정도를 보인다. 청다옥의 건물수량(20.24 톤/ha)은 광평옥과 비슷하였으며, TDN수량(13.80 톤/ha)도 광평옥과 비슷하였다. 청다옥의 종실수량(8.51 톤/ha)은 장다옥보다 많았다. 4∶1(모본:부본) 재식비율로 동시 파종하여 채종시험한 결과 모본의 출사기와 부본의 화분비산기간이 일치하였으며 채종수량은 1.8 톤/ha이었다. 청다옥은 전국적으로 재배가 가능하다.

Northern corn leaf blight caused by Exserohilum turcicum Pass is considered the most important disease infecting corn (Zea mays L.) in the Peoples' Republic of Korea (North Korea). It contributes to the food shortage in North Korea. The objectives of the current research were to study resistance expression and responses of corn crosses made between ten hybrids from North Korea and inbreeding lines (S3-4 stage) from the Republic of Korea (South Korea). The experiments were conducted in six trials with a total of 184 crosses including two commercial hybrids in each trial. The trials were conducted at two locations in North Korea (Mirim and Eunsan) and one location in South Korea (Gunwi) under natural infestation of E. turcicum. Host plant responses were rated on a scale of 1 (highly tolerant) to 9 (highly susceptible). A total of 111 crosses (62.4%) showed significant tolerant or susceptible response variations among three locations; 42 crosses (22.8%) at two locations and 69 crosses (39.0%) at one location, respectively. At least 8 crosses of high level of tolerance and 12 crosses of high level of susceptibility showed significantly different biotic responses (P = 0.05). The results of the current study and historical reviews of E. turcicum epidemics in both North and South Korea suggest that breeding of tolerance with quantitatively inherited genes should be carried out for a sustainable corn production in North Korea.

We studied on the diallel cross analysis of three different types of corn(Zea mays L.); supersweet(ss), sticky waxy and normal field corn in Korea and China. Four inbred lines each of three different types were crossed in a full diallel. Testing of 66 F1 crosses were made at two locations in Korea and China, respectively, in 2009. The objectives of the experiment was first to study different levels of heterosis among three types. In Korea, average ear length of 16 F1 crosses was the longest in N x wx (197mm), followed by wx x ss (193mm) and N x ss (191mm). Average of ss, wx and N were 135mm, 171 mm and 155mm. The relatively high level of N might be location specific breeding results, where the testing was done at the center of waxy corn breeding. Trends of three F1 crosses in China were similar with normal and supersweet corn. The result of this study has supported for breeding of high quality sticky-supersweet and high yield potential of normal -supersweet corn hybrids in the developing world to provide nutrition, sugar and other minerals such as Vitamin A and anthocyanin, simultaneously as a high quality food.

The appearances of growth and yield according to the cultivation types were investigated in chalok 1. The days to harvest under double vinyl house, open mulching and open cultivation were 87.7, 95.8, and 101.8 days, respectively and significantly different in each cultivation types. The branched ears of open mulching, double vinyl house and open cultivation were started at 7,8, and 13 days after silking, respectively. The frequency of branched ear per total plants to double vinyl house, open cultivation and open mulching were 10%, 13%, and 19%, respectively. The ear weight of open mulching and open cultivation was superior to branched ear weight. The yields (kg/10a) of double vinyl house, open mulching and open cultivation were 755.7kg, 740.7kg, and 530.0kg, respectively. The yields(kg/10a) of double vinyl house and open mulching were significantly different to that of open cultivation and LSD(5%) was 133.42. Thus, early cultivations in double vinyl house were more beneficial than other cultivation types because of the highest yield and the lowest branched ear.