Maize (Zeae mays L.) is a second important crop in the country and it is first staple food in high land region. The national average yield is 2.2 t/ha. About 80% maize areas falls in this region. An introduced fungus Gray Leaf Spot (GLS) caused by Cercospora zeae-maydis has caused yield loss an average of 75%. Genetic resistance has been effective control strategy to manage this disease. The main objectives of this work were to develop, evaluate and identify high yielding cultivars tolerant to GLS. Three sets of trials were conducted in Nepal and Korea. GLS evaluation trial-I consisted of 73 genotypes, GLS evaluation trial-II composed of 38 genotypes and mid altitude hybrid evaluation trial-III consisted of 12 genotypes. Exotic, semi exotic and local germplasm of different origins were used. Among these tested genotypes, tolerant genotypes were Thai 717S31-21-3×[TZMi407 × TZMi211-11- 2-1-1-B-B-B-B-B (5.2t/ha), Pioneer12 × MASynVAR-5 F2 (5.0 t/ha) and MA SynVAR-5 F2 × Thai 919 S3 4-5-4 (4.7t/ha) with GLS mean score 2.7, 1.5 and 1 respectively in trial-I. In trial-II, superior genotypes were KYM33 × TZi3 (7.6t/ha), KYM33 × TZi18 (7.5 t/ha) and KYM33 × P45 (7.4 t/ha) with GLS scores 1.4, 2.4 and 2.5 respectively. Similarly in trial-III, high yielding genotypes were MASynVAR-5 (11.0t/ha), and TZMi407×87036- 9-1-1-1-B-B-B/TZMi102×90113-5-3-2-2-B-B-B-B (9.8t/ha). These hybrids and their parents will use to introgress resistant genes to breed better tolerant maize cultivars for Nepal.

Downy mildew (DM) caused by the fungus Peronosclerospora sorghi is one of the most serious diseases reducing maize (Zea mays L.) production in East Timor. We have conducted three trials of DM resistant (R) and non-DMR source populations in three locations; Loes, Dili and Lospalos. Materials were developed by using DMR-ESR-Y and MO5-5-RUVT-EE (TZEE-Y) (IITA) and Suwan 5 (Thailand). Three sets of random mating, incomplete diallel crosses and parent populations were planted with three replications in one meter row with RCBD. Data assessment of DM infection was rated based on 1 – 9 rating score (1 = highly tolerant and 9 = highly susceptible) from 2 and 4 weeks before flowering. In Comoro, Dili, 32 genotypes exhibited very low DM infection with coefficient of variance and mean 17.2% and 3.9, respectively. BISI-2 (Indonesian hybrid) and TH2 (Timor Hybrid 2 crossed from two DMR OPVs, Indonesian Arjuna and Suwan 5) showed outstanding commercial value (CV). Twelve cultivars of MO5 were varied in CV. At Loes Research Station, genotypes showed high variation in DM infection. Average heterotic effect of 36 F1 crosses for DM tolerance was 29.5%. Mean parent value and F1 indicated negative correlation for DM infection. The result showed that to breed high resistance is difficult. However, breeding for host tolerance with polygenic system with a threshold nature is possible.

Maize is expected to be planted in June after harvest of winter barley for the double cropping of forage maize-barley. But maize yield tends to be reduced rapidly with late planting after mid-May, so the pre-requisite of maize variety for the double cropping of maize-barley is less reduction of growth and yield at the condition of late planting in June. In order to select domestic forage maize variety adapted to late planting in June after barley harvest, Kwangpyeong-ok, Gangda-ok and Jangda-ok in 2007 and Kwangpyeong-ok, Gangda-ok and Cheongan-ok in 2008 were planted on June 13 and June 21, and plant growths and yields were compared with early planting on April 24 and May 31, respectively. In 2007, Ear number per plant was as high as 0.98 at Kwangpyeong-ok compared to 0.89 and 0.56 of Gangda-ok and Jangda-ok, respectively, at late planting on June 13. TDN and grain yield of Kwangpyeong-ok were the highest among three variety as 1,037 and 710 kg/10a, and yield reduction of Kwangpyeong-ok compared to early planting were 24% and 28 %, which were 7% and 8% lower than Gangda-ok and 22% and 50% lower than Jangda-ok, respectively. In 2008, TDN and grain yield at late planting on June 21 of Kwangpyeong-ok were also the highest among three varieties as 1,157 and 854 kg/10a at late planting on June 24, and yield reduction of Kwangpyeong-ok by late planting were 21% and 19%, which were 10% and 11% lower than Gangda-ok and 22% and 50% lower than Jangda-ok, respectively. It was concluded that proper maize variety adapted to late planting for the double cropping of forage maize-barley was Kwangpyeong-ok because of its higher ear bearing, less reduction of TDN and grain yields at the condition of late planting.

흑진주찰(수원찰57호)은 자식계통 KBW24을 종자친으로하고 KBW2를 화분친으로 하여 교잡된 단교잡종이며 고품질 검정찰옥수수이다. 흑진주찰은 2003년 생산력검정시험을 거쳐, '06~'08년 3년 동안 전국 5개 지역에서 지역적응시험을 실시한 결과 그 우수성이 인정되어 2008년 농작물 직무육성 신품종으로 결정되었다. 이 품종의 주요특성을 요약하면 다음과 같다. 1. 흑진주찰의 출사일수는 74일로 중만숙종에 속하며 이삭 길이가 16.0 cm로 찰옥1호

평안옥은 자식계통 KS140과 KS94의 교잡으로 육성된 다수성인 단교잡종이다. 2005년 생산력검정시험을 거쳐, 2006~2008년 3년 동안 4지역에서 지역적응시험을 실시한 결과 그 우수성이 인정되어 2008 농작물 직무육성 신품종선정위원회에서 신규우량품종으로 결정되었다. 이 품종의 주요특성을 요약하면 다음과 같다. 1. 평안옥의 종피색은 황색이며 입질은 반경립종이고, 출사일수는 광평옥보다 3일 늦다. 간장 및 착수고는 광평옥과 비슷하였으며, 후기녹

우리나라 찰옥수수 및 종실용 옥수수 품종들의 교배친인 11개의 자식계통의 유전적 다양성 및 계통간 유연관계를 50개의 SSR 마커를 사용하여 분석한 결과는 다음과 같다. 1. 50개의 SSR primer들은 찰옥수수 및 종실용 옥수수 품종들의 교배친인 11개 자식계통들에서 총 171개의 대립단편을 증폭시켰고, 각 SSR primer들에서 증폭된 대립단편의 수는 최소 2개에서 최대 6개의 범위로 나타나 SSR loci당 평균 3.4개가 증폭되었으며, 유전

Downy mildew (DM) caused by the Peronosclerospora maydis is considered the most damaging disease of maize (Zea mays L.) in South Asia. In East-Timor, it has been widely spread and considered as the major stress of maize production. It was observed at Loes Research Station and farmers’ field since 2004. All materials exhibited high susceptibility to DM infection at the CIMMYT trial. Only Suwan5 (Thailand), LYDMR (CIMMYT) and Arjuna (Indonesia) showed tolerance. Different trials with 900 crosses were tested at 5 locations; Lospalos, Dili, Comoro, Aileu and Loes in 2006/2007 In 2008, high DM infection was observed at Loes. Crosses of Suwan5, NAI, Arjuna and DMR-ESR-Y (IITA)with tropical and temperate germplasm showed tolerance. The International Corn Foundation (ICF)/KNU team with the Ministry of Agriculture have run breeding research three cycles yearly. By 2007, the joint team developed an open-pollinated variety (OPV) with combined tolerance to DM and drought. The Ministry named it "NAI", means "honorable" in national language. Hybrid breeding for both DM and drought are being developed.

The common corn rust caused by Puccinia sorghi Schw. is widely distributed southern regions of temperate zones and sub-tropical regions world wide. It has been reduced corn yield significantly in Texas and Hawaii. The first author has observed incidence of this disease in Korea since ten years ago both in South (Kunwi, Ilsan, Pyungchang) and North Korea (Tongcheon). P. sorghi had very high infection in Jeju Island with over 2000 mm rainfall in 2008 on commercial hybrids from USA (DK 729, Pioneer 3394, P32P75) and Korea. All showed high susceptibility. Genetic tolerance could be the most economic way to control these fungi. The occurrence of this disease in Korea may be caused by environment changes. Pro-environment tolerance breeding with quantitatively inherited genes of host crop can guarantee for the durability and sustainability of crop cultivars under continuous changes of weather and environments.

The effects of CO2 enrichment on growth of maize (Zea mays L.) were examined. Parameters analyzed include growth characteristics, yields, photosynthetic rates, evaporation rates and photosynthesis-related characteristics under elevated CO2 . The plants were grown in growth chambers with a 12-h photoperiod and a day/night temperature of 28/21~circC at the seedling stage and 30/23~circC from the silking stage. The plants were exposed to two elevated CO2 of 500, 700ppm and ambient levels (350 ppm). Chalok 1 and GCB 70 germinated three days after seeding, and germination rates were faster in the elevated CO2 than the control. Germination rates displayed significant differences among the CO2 treatments. At the seedling stage, leaf area, top dry weight, and photosynthetic rates, and plant height indicated positive relationship with elevated CO2 concentrations. At the 5~6 leaf stage, CO2 concentration also indicated positive relationship with plant height, leaf area, top dry weight, and photosynthetic rates. At the silking stage, increased plant height of Chalok 1 was noted in the CO2 treatments compared to the control. No significant differences were noted for GCB 70, in which leaf area decreased but photosynthetic rates increased progressively with CO2 concentration. Stomatal aperture was a little bigger in the elevated CO2 than the control. CO2 concentration was negatively related to stomatal conductance and transpiration rates, resulting in high water use efficiency.

Aphids are generally considered as a major pest of corn. Thus, yield losses due to aphid infection can be considerable. Rhopalosiphum padi - the birdcherry oct aphid seems to be prevalent aphid species on maize in Korea. Aphid resistance of 91 Fls was assessed at two locations in Korea. In studies of combining ability for aphid resistance to different locations, GCA mean square was 4.48 times grater than that of SCA mean square. Thus, additive gene action was more important than that of non-additive gene action to aphid resistance. In two locations, inbreds 2, 4, 5 and 10 had negative GCA effects for aphid resistance.

It has been hypothesized that efficient exclusion of methylated retrotransposons and repeated DNA region is one of the rapid and cost-effective approaches for comprehensive gene discovery in large genome size of maize. Three kinds of methylation-sensitive restriction enzymes, HapII, MspI and McrBC, were used to identify the restriction frequency of cytosine methylation sites in maize genome. Roughly 60% of total maize genomic DNA was restricted less than 500bp by McrBC, and the most of restricted small size fraction was composed retrotransposon. In order to validate the efficient construction of gene-rich shotgun library, we compare two gene-rich methyl-filtration shotgun libraries using in vivo and in vitro methyl-filtration system. The size selected DNA fraction by Sau3A-McrBC enzyme treated was very stable and has not appeared modification in E. coli, but most insert DNA size of partially digested with Sau3A were decrease less than 500bp by bacterial methylation-modification system. In compare of retroelements portion, A 44.6% of the sequences were retroelement in unmethyl-filtered library, and the most of them was Copia type, such as Prem, Opie and Ji. The portion of retroelement was drastically decreased to 25% and 20% by in vivo and in vitro filtration system, respectively.