The global rice reduction due to drought averages 18 Mt, especially, 23 Mha of rice fields in Asia are drought-prone. However, rice breeding programs focusing on drought resistance have made little progress to date. Because proper screening approaches with large scale were not developed to evaluate the drought tolerant degree. In here, we have developed of leaf water loss rate with plastic ware in dark conditions for large screening. Through this bioassay system, we examined drought phenotype degrees of 650 rice varieties. To validate whether this optimized bioassay system is corelated with drought phenotype, we chose 14 varieties having the lowest or highest of the water loss rate. We observed the visual drought phenotype and agricultural traits in green house and field conditions. Apo and Samgang having the lowest of leaf water loss rate showed drought tolerance phenotype, whereas Yeolbaeg and Milyang254 having the highest of leaf water loss rate showed drought sensitive phenotype. Apo displayed proper root length trait and Samgang showed good root dry trait in the greenhouse conditions. These results suggest that a simple screening procedure with water lose rate of leaves is effective to perform large scale screening for drought phenotype in rice.

Bakanae disease is one of the most serious and oldest problems of rice production, which was first described in 1828 in Japan (Ito and Kimura 1931). This disease may infect rice plants from the pre-emergence stage to the mature stage, with severe infection of rice seeds resulting poor germination or withering (Iqbal et al. 2011). Under favorable environmental conditions, infected plants have the capacity to produce numerous conidia that subsequently infect proximate healthy plants, resulting in major yield loss (Ou 1985). One hundred sixty nine NILs, YR28297 (BC6F4) generated by five backcrosses of Shingwang with the genetic background of susceptible japonica variety, Ilpum were used for QTL analysis. Rice bakanae disease pathogen, CF283, was mainly used in this study and inoculation and evaluation of bakanae disease was performed with the method of the large-scale screening method developed by Kim et al. (2014). A major QTL for resistance against bakanae disease on chromosome 1 was identified using SSR marker, RM9, which explaining 65 % of the total phenotype variation. The major QTL designated as qBK1 and mapped to a 4.4 Mbp region between RM24 (19.30 Mb) and RM11295 (23.72 Mb). The results of this study are expected to provide useful information toward developing resistant rice lines to this detrimental fungal disease.

Bakanae disease incidence threat is an increasing trend in the top rice growing countries. Despite it is essential to identify the resistant genes and underlying mechanisms of bakanae disease to develop resistant varieties, there are very limited genetic studies on bakanae disease in rice. The indica rice variety Shingwang was selected as resistant donor to bakanae disease. One hundred sixty nine NILs, YR28297 (BC6F4) generated by five backcrosses of Shingwang with the genetic background of susceptible japonica variety, Ilpum were used for QTL analysis. Rice bakanae disease pathogen, CF283, was mainly used in this study and inoculation and evaluation of bakanae disease was performed with the method of the large-scale screening method developed by Kim et al. (2014). The proportion of healthy plants of Shingwang and Ilpum after inoculation was confirmed using bakanae disease pathogen, CF283. While inoculated Ilpum showed thin and yellowish-green phenotype which is typical symptom of Bakanae disease, Shingwang showed similar healthy phenotype with control plants. A major QTL for resistance against bakanae disease on chromosome 1 was identified using SSR marker, RM9, which explaining 65 % of the total phenotype variation. The major QTL designated as qBK1 and mapped to a 4.4 Mbp region between RM24 (19.30 Mb) and RM11295 (23.72 Mb). The information of qBK1 could be useful for improving rice bakanae disease resistance in marker-assisted breeding.

‘설레미’는 국립식량과학원 상주출장소에서 2011년도에 육성한 조생 고품질 고식미 도정특성 우수 품종이다. ‘설레미’는 남부중산간지, 북부평야지 및 중산간지, 남부고냉지 및 동북부해안지 보통기 보비재배에서 평균 출수기가 8월 1일로‘오대벼’보다 3일 늦은 조생종이다. 간장은 73 cm로 오대벼보다 작으며, 수당립수는 많고 등숙비율이 높은 중립종에 속한다. 위조현상은 나타나지 않았으며 성숙기 하엽노화가 늦고수발아는 ‘오대벼’보다 안되는 내수발아성이다. 내냉성은 보통이다. ‘설레미’는 도열병에 저항성 반응을 보였다. 입형은현미장폭비가 1.90으로 단원형이며 심복백이 없고 맑고 투명하다. ‘오대벼’에 비해 아밀로스함량은 낮고 단백질함량은 약간 높으며 밥맛은 매우 양호하다. 도정율, 백미완전미율이 각가 77.5%, 97.7%로 ‘오대벼’에 비해 높다. 쌀수량은 보통기표준재배에서 5.60 MT/ha로 ‘오대벼’보다 7% 많은 편이다.

Bakanae disease of rice, caused by Fusarium moniliforme Sheldon, the imperfect stage of Gibberella fujikuroi, is one of the most important rice diseases worldwide, but no rice variety has been found to be completely resistant to this fungus. Cultivation of resistant cultivars is the most beneficial way of reducing quantitative or qualitative losses to for bakanae disease in rice. To facilitate the study of this disease, accurate and large scale screening methods were developed for the inoculation and evaluation of Bakanae disease. Even and large scale infection was achieved by using F. moniliforme spore in tissue embedding cassette and seedling tray. The efficiency of F. moniliforme infection with the concentration of 1×106 spore/ml caused better distribution (F-value=33.96) than 1×102 (F-value=10.69), and 1×104 spore/ml (F-value=2.63). We established new criteria of healthy and non-healthy plant, and introduced calculation of proportion of healthy plants to meet fast evaluation of resistance level of each variety. The effect of F. moniliforme strains containing different genetic background was also evaluated with rice varieties to figure out the stability of resistance level. GA3 response of rice variety was significantly correlated with bakanae disease, but it did not adequate for direct indicator of bakanae disease resistance. These results indicated that a large scale infection method developed in this study is fast and reproducible, as well as a disease evaluation system provides an accurate measurement of bakanae disease resistance of rice.

벼흰잎마름병은 국내에서 가장 주요 병해 중 하나이다. 벼흰잎마름병 저항성유전자 xa5는 국내 흰잎마름병 레이스에 광범위 저항성을 보인다. 2010년 국립식량과학원 기능성작물부에서는 벼흰잎마름병 저항성 유전자 xa5를 가진 벼 신품종 ‘신백’ 육성하였다. ‘신백’은 고품질 복합내병성인 ‘익산469호’를 모본으로 사용하고, 흰잎마름병 저항성유전자 xa5를 가진 계통 HR23966-22-1-2를 부본으로 사용하였다. ‘신백’의 출수기는 보통기 보비재배에서 8월 11일로 ‘남평벼’보다 5일 빠른 중생종이다. 간장은 76 cm로 단간이며 수수가 적고 수당립수가 많으며, 등숙율은 남평벼보다 낮은 편이다. ‘신백’은 흰잎마름병 검정에서 K1, K2, K3및 K3a에 강하였고, 바이러스병인 줄무늬잎마름병에 강하다. 잎도열병은 중정도 저항성이며, 목도열병은 이병율이 낮은 편이다. ‘신백’은 쌀의 심복백이 없으며, 아밀로스함량과 단백질 함량은 ‘남평벼’와 비슷한편이고, 도정특성 및 완전미율은 남평벼보다 약간 낮은 편이다. ‘신백’의 쌀수량은 보통기 보비재배에서 5.75 MT/ha, 이모작 재배에서 5.49 MT/ha, 만식재배에서는 5.18 MT/ha이였다.

‘백옥찰’은 내도복성이며 복합내병충성을 갖춘 중만생종 찰벼 품종을 육성하고자 국립식량원 기능성작물부에서 육성된 새로운 찰벼품종이다. ‘백옥찰’의 출수기는 중부평야지 및영․호남평야지 보통기 보비재배에서 8월 20일로 ‘신선찰벼보다 9일 늦은 중만생종이며, 이모작에서는 ‘남평벼’ 보다 1일 늦고, 만식에서는 ‘남평벼’ 보다 3일 늦은 중만생종이다‘백옥찰’의 줄기 두께는 ‘신선찰벼’와 같이 중간 정도이나 강도는 ‘신선찰벼’보다 강한 편이고 분얼개도는 보통이며, 탈립은 ‘신선찰벼’에 비해 잘 되는 편이다. 주당수수는 ‘신선찰벼보다 3개가 적으나 수당립수는 20여개가 많고 등숙비율은 ‘신선찰벼’에 비해 9% 높으며 현미 천립중 또한 ‘신선찰벼에 비해 무거운 편이다. 도정특성은 ‘신선찰벼’보다 다소 높으며, 특히 백미 완전립율이 ‘신선찰벼’에 비해 월등히 높은 편이다. 현미 장폭비는 1.71로 ‘신선찰벼’에 비해 쌀알이 약간 작은 편이며 단백질 함량 및 알카리 붕괴도 등 이화학적 특성은 ‘신선찰벼’와 같은 편이다. 불시출수가 없었으며, 성숙기의 엽노화가 중간 정도를 보였다. 내냉성 검정 결과 ‘신선찰벼’보다 출수지연은 적었고 및 냉수구 임실율은 약간 높았으며 수발아는 잘 안되는 편이었다. 도복관련형질에 있어서 벼키는 ‘신선찰벼’와 같으나 중심고, 좌절중, 모멘트 및 도복지수 등 도복관련 형질에서는 전반적으로 ‘신선찰벼’보다 큰 편이었고 포장 도복은 없었다. 잎도열병 밭못자리 검정결과 ‘백옥찰’은 전국 평균 도열병 저항성 정도가 ‘신선찰벼’와 비슷한 저항성을 보였으며, 목도열병의 경우 현지 포장검정에서는 발병되지 않았고 내구저항성은 강하였다. 흰잎마름병(K1-3), 줄무늬잎마름병에는 저항성이고 오갈병 및 검은줄오갈병에는 감수성이었다. ‘백옥찰’의 수량성은 중부평야, 호남․ 충남평야 및 영남평야지 보통기 보비재배 6개소에서 쌀 수량은 526 kg/10a으로 대조품종보다 9% 증수된 높은 수량성을 보였다. ‘백옥찰’은 중부 및 영호남내륙평야 1모작지대에 적응성이 높은 중만생종이다.

초다수성이며 복합내병성인 고품질 통일형 벼를 육성하고자 복합내병성이며 수량성이 높은 ‘밀양160호’(‘아름벼’)와 준조생이며 내만식성이 높고 복합내병성 다수성 품종인 ‘용주벼’(‘수원333호’)를 부본으로 인공교배를 하여 ‘세계진미’를 육성하였다. ‘세계진미’의 출수기는 평야지 보통기 다비재배에서 8월 17일로 중만생종이며, 간장은 82 cm로 ‘다산벼’보다 약간 크고 수당립수는 ‘다산벼’보다 적은 편이며 현미 천립중은 22.2 g으로 ‘다산벼’와 비슷하였다. ‘세계진미’는 불시출수, 수발아 및 포장도복은 없었으며, ‘다산벼’에 비해 내냉성은 약한 편이다. ‘세계진미’는 잎도열병, 목도열병, 줄무늬잎마름병, 오갈병 및 흰잎마름병(K1, K2, K3, K3a)에 강하고, 검은줄오갈병에는 중정도의 저항성을 보였으나 벼멸구에는 감수성이다. ‘세계진미’의 단백질함량은 7.9%로 ‘다산벼’에 비해 다소 높은 편이나, 아밀로스함량은 17.2%로 ‘다산벼’와 비슷하였다. 특히 ‘세계진미’의 물리성과 밥맛 관능검정결과 일반벼인 ‘추청벼’ 수준 이상의 양호한 취반특성을 보였다. ‘세계진미’의 쌀수량성은 2006부터 2008년까지 3년간 실시한 지역적응시험 보통기 다비재배(6개소)에서 7.01 MT/ha로 ‘다산벼’ 대비 8% 증수 되었다. ‘세계진미’의 적응지역은 중부 및 영호남 평야지이다.

Brown rice grain pigments of black rice have a higher content of bioactive substances such as anti-mutagenic substance than the non-pigmented rice grain. The major anthocyanin pigment contained in black rice was cyanidin-3-glucoside. This study was conducted to establish a rapid analysis method for determining cyanidin-3-glucoside contents in flour and whole rice seeds of black rice using VIS/NIRS technique. A total of 60 black rice samples were used for VIS/NIRS equation model development and validation. The value of coefficient of determination of external validation (r 2 ) and standard error of performance (SEP) in whole rice seed sample were 0.653 and 97.2, respectively. Therefore, the value of it seemed to be difficult to analyze cyanidin-3-glucoside content in whole rice seed samples using VIS/NIRS. However, in rice flour sample, the best accurate equation model was obtained from the partial least square regression (PLS) method. The value of r 2 , SEP and bias were 22.5, 0.922 and -1.45 in the calibration transformed to the N-point smooth of log 1/R signal, 5 factors, respectively. Therefore, the results of our study clearly demonstrate that the VIS/NIRS method would be applicable only for rapid determination of cyanidin-3-glucose content in black rice flour samples.

The use of functional markers, it is expected to make direct identification about genetic diversity at DNA level and overcome the problem of recombination /linkage. These markers can be used to identify interesting alleles in a breeding program and indirectly select for the trait, saving money, time and labor. Bacterial blight of rice caused by Xanthomonas oryzaepv. Oryzae is a destructive disease in rice production worldwide. No bactericide is effective to control the bacterial blight disease yet. Xa3, which is a gene conferring resistance to BB of the rice plant has been previously characterized by map-based cloning. We have cloned and sequenced the Xa3/xa3 gene in Korean cultivar, Hwayoung, Ilmi and Goun with gene specific primers. Our work detected polymorphisms and PCR-based allele specific SNP markers were developed. Susceptible or resistant individuals from an F2 population developed from across between Milyang244 and Ilmi, Korean germplasms and near isogenic lines carrying BB resistance genes were screened with allele specific markers. We found that the genotype completely matched their phenotype to BB using ASP-primers. These markers could be effective to marker-assisted selection for the Xa3 gene in rice breeding programs.

Rice stripe disease, caused by rice stripe virus (RSV), is one of the major virus diseases in east Asia. The objective of this study was conducted to identify new resistance genetic source to rice stripe virus (RSV) disease. Genetic diversity of 155 rice cultivars was evaluated using 9 co-dominant InDel markers and STS marker ST10. These cultivars were classified into two groups by cluster analysis based on Nei`s genetic distances. The marker showed different band pattern among RSV resistance or susceptible cultivar. In comparison with bioassay for RSV resistance and genotyping using SSR markers showed that Stv-bi and InDel 7 marker observed recombination value within 3.8% and RSV resistance gene was closely related to InDel 7. Also InDel 7 divided as resistance type alleles and susceptible type alleles except for some varieties. Interestingly, 02428, Daw dam, Erguailai, Padi Adongdumarat, PERVOMAJSZKIJ, and Tung Ting Wan Hien 1 showed Japonica type in InDel 7 marker. However, these cultivars revealed resistant to RSV bioassay. These results indicate that those cultivar can be able to get the different gene resistance with Stv-bi gene. Newly identified resistance gene is considered useful for improving RSV resistance in japonica rice. Therefore, we will progress the allelism test and genetic analysis for identification of new gene source.

In order to improve rice dough functionality, we cloned 4 kinds of high-molecular-weight glutenin subunit (HMW-GS) genes from bread wheat, ‘Jokyeong’. Among them, we first examined Dx5 gene to generate marker-free transgenic rice for advanced quality processing of bread and noodles. The GluB1 promoter was inserted into binary vector for seed specific expression of the Dx5 gene. Two expression cassettes comprised of separate DNA fragments containing only the high-molecular-weight glutein subunit (HMW-GS) protein (Dx5) and hygromycin phosphotransferase II (HPTII) resistance genes were introduced separately to tumefaciens EHA105 strain for co-infection. Each EHA105 strain harboring Dx5 or HPTII was infected to rice calli at 3: 1 ratio of Dx5 and HPTII, respectively. Then among 66 hygromycin-resistant transformants, we obtained two transgenic lines inserted both with Dx5 and HPTII gene to rice genome. We reconfirmed integration of the Dx5 and HPTII genes into the rice genome by Southern blot analysis. Wheat Dx5 transcriptsin rice seeds was examined with semi-quantitative RT-PCR. Finally, the marker-free plants containing only Dx5 gene were successfully screened at T1 generation. This result also provides that co-infection system with two expression cassettes could be efficient strategy to generate marker-free transgenic rice plants.

Amylose content of rice endosperm is one of the determinants of rice eating quality. This study was conducted to elucidate the mode of inheritance of dull gene in Milyang262, tentatively designated as du7(t), and to identify the molecular marker for du7(t) to be employed in marker-assisted breeding and gene pyramiding. Genetic analysis was carried out on F2 population derived from a cross between Junam and Milyang262. The low amylose content of Milyang262 was indicated to be under single recessive control. Allelism tests were as well conducted by crossing Milyang262 with Baegjinju and Baegokchal, which harbor du1 and wx gene, respectively. du7(t) was demonstrated to be inherited independently to du1 and wx. F2 population of Baegokchal/Milyang262 was used for molecular mapping. Linkage analysis was conducted on a population consisted of 120 individuals by several SSR markers. Initial mapping indicated that du7(t) is located on the end of long arm of chromosome 6 between SSR marker RM20590 and RM3509. To fine map the gene, a bigger population and several additional markers were employed. du7(t) was further mapped to a 1.74 Mb region between two SSR markers (RM6926 and RM412). Furthermore, we indentified three SSR markers that co-segregated with du(t) i.e. RM6811, RM3765, and RM176.

2000년대 후반 국내 쌀 소비량의 지속적인 감소와 MMA물량으로 인한 국내 양곡 재고부담이 가중되면서 쌀가공품에대한 관심과 함께 원료곡의 원가절감 대안으로 초다수성 품종이 재조명을 받게 되었다. 따라서 가공용으로 사용되는 원료곡의 가격경쟁력을 높이기 위해서 복합내병성이며 수량성이 높은 ‘한아름2’를 육성 하였다. ‘한아름2’의 출수기는 평야지 보통기 다비재배에서 8월 14일로 중생종이며, 간장은 76㎝로 ‘다산벼’보다 약간 크고 수당립수는 ‘다산벼’보다 약간적은 편이나 등숙률이 85.7%로 높고 현미천립중은 23.0g으로 비슷하다. ‘한아름2’의 불시출수와 수발아 및 포장도복은없었으며, 내냉성은 약한 편이다. 잎도열병, 목도열병, 줄무늬잎마름병, 오갈병 및 흰잎마름병(K1, K2, K3, K3a)에 강하고,검은줄오갈병에는 중정도의 저항성을 보였고 벼멸구에는 감수성이다. 쌀알은 맑고 심백이 약간 있으며 단백질함량은 8.2%로 ‘다산벼’보다 높았으나 아밀로스함량은 17.5%로 ‘다산벼’보다 낮았다. ‘한아름2’의 쌀수량성은 2008년부터 2010년까지 3년간 실시한 지역적응시험 결과 보통기 다비재배(6개소)에서 7.58MT/ha로 ‘다산벼’대비 13% 증수되었다. ‘한아름2’는 중부 및 영호남 평야지가 적응지역이다.

‘영호진미’는 쌀의 외관과 밥맛이 양호한 고품질 벼를 육성하고자 ‘03/'04 동계에 밥맛이 우수한 양질미 히또메보레와단간이면서 내병성이 양호한 주남벼를 부본으로 인공교배하여 육성하였다. 그후에는 조기에 고정된 계통을 얻고자 약배양을 실시하였으며, YR24733Acp10 계통을 선발하여 밀양228호의 계통명을 부여하였다. 07~’09년 3개년간 지역적응시험결과 우수성이 인정되어 농작물 직무육성 신품종 선정위원회에서 국가목록 등재 품종으로 선정되었다. ‘영호진미’는 영남평야 1모작지에 적응성이 높은 중만생 고품질 벼 품종이다.‘영호진미’의 출수기는 남부평야지와 남부 및 서남부해안지보통기재배에서 8월 21일로 ‘남평벼’보다 5일 늦은 중만생종품종이다. 간장과 수당립수는 ‘남평벼’보다 적은 편이고 현미천립중은 ‘남평벼’보다 약간 무거운 편이다. 도정특성은 ‘남평벼’와 비슷한 편이고 단백질함량은 ‘남평벼’보다 낮고 밥맛은 양호한 편이다. 불시출수는 없으며, 수발아는 ‘남평벼’와비슷하였으며, 내냉성은 중정도이고 냉수구 출수지연일수가긴 편이다. 잎도열병 밭못자리 검정 결과 약한 반응을 보였고,흰잎마름병에는 레이스 K1, K2, K3에는 저항성이지만 K3a에는 이병성이다. 줄무늬잎마름병에는 저항성이지만 오갈병과검은줄오갈병에는 약하고 벼멸구 등 해충에도 약하다. ‘영호진미’는 영호남 평야지 1모작 적응 품종으로, 수량성은 2007년부터 2009년까지 3년간 실시한 지역적응시험 결과 남부 및남서 해안지와 호남평야지, 영남평야지의 보통기 보비재배 10개소에서 5.44 MT/ha로 ‘남평벼’보다 3% 감수되었다.

국내 주요 해충인 끝동매미충에 대한 저항성 품종‘청남’은 ‘기누히까리’와 ‘밀양189호’를 각각 모본과 부본으로 인공교배 한 후 약배양으로 육성하였으며, 주요 연구결과는 아래와 같다. 출수기는 평야지 보통기 재배에서 8월 11일로 중생종이며 수당립수는 ‘남평벼’보다 적은 편이고 현미천립중은 무거운 편이다. 불시출수는 발생하지 않았으며, 수발아는 ‘남평벼’보다 약간 높은 편이고, 포장도복은 없었으며, 내냉성은 ‘남평벼’와 비슷하다. 잎도열병 밭못자리 검정 중 정도 저항성을 보였으며, 줄무늬잎마름병과 흰잎마름병(K1, K2, K3)에는 강하며, 바이러스병을 매개하는 끝동매미충에 저항성으로 오갈병에 포장저항성을 나타낸다. 검은줄오갈병에 약하고 벼멸구 등 충해에는 감수성이다. ‘청남’의 끝동매미충 유전분석을 수행한 결과 1개의 단순우성유전자에 의해 지배됨을 확인하였다. ‘청남’의 쌀은 맑고 투명하며 완전미율이 높았으며, 밥맛은 양호한 편이다. ‘청남’의 수량성은 2007년부터 2009년까지 3년간 실시한 지역적응시험 보통기 보비재배 11개소에서 5.43 MT/ha, 이모작재배에서는 5.00 MT/ha, 만식재배에서는 5.18 MT/ha이었다.

한강찰 1호'는 국립식량과학원 기능성작물부에서 2006년도에 육성한 중생 복합내병충성 통일형 찰벼 품종으로 그 주요 특성은 다음과 같다. 1. 출수기는 중부평야지 및 영 호남평야지 보통기 보비재배에서 8월 13일로 신선찰벼 보다 3일 늦은 중생종이다 2. '한강찰 1호'의 주당수수는 10개, 수당립수는 156개의 수중형이고, 등숙비율은 85%, 현미 천립중은 21.2 g이다. 3. 성숙기의 엽노화는 중간 정도이며 못자리일수 50일묘 이앙 시에 불시출수가

Rice is a staple food for more than 50% of the world's population. Embryo comprises only 2 to 3% of the weight distribution of the entire pericarp but has higher concentration of vitamins, proteins, and essential fatty acids than the other parts of grains. Moreover, α-tocoperol, γ-oryzanol, phytic acid and γ-aminobutric acid that have nutraceutical value are abundant. Increasing the volume of embryo assures the fortification of nutritional value of rice grain. We developed new black waxy giant embryo rice, Milyang 263 by crossing Josaengheugchal, a black waxy rice variety, and get, a giant embryo mutant generated by tissue culture. The nutrient contents and physical properties of Milyang 263 were compared with several giant embryo mutants and normal embryo rice varieties. Changes in the nutrient properties after germination were also observed. Results indicated that this new black waxy giant embryo rice, Milyang 263, offers a promising source for improving nutritional quality of rice especially anthocyanin, essential minerals, and GABA.

‘만미벼’는 작물과학원 영남농업연구소(현 국립식량과학원 기능성작물부)에서 2002년도에 육성한 중만생 저아밀로스 반찹쌀 품종으로 주요특성과 수량성을 요약하면 다음과 같다. 1. 출수기는 남부평야지의 보통기재배에서 8월 16일로 ‘동진벼’ 보다 2일 빠른 중만생종이다. 2. 수당립수는 ‘동진벼’ 보다 18개 많으나, 현미천립중은 19.9 g으로 ‘동진벼’ 보다 가벼운 편이며 등숙비율이 약간 떨어진다. 3. 위조현상에 강하고 성숙기 엽노화가 느린 편이며 내

Field experiments were conducted to investigate persistence of Chinese milk vetch(CMV) seed under naturally reseeded CMV-rice cropping systems during the period of 2007～2009. Persistence of the CMV seeds were evaluated in the naturally reseeded CMV-rice field on different tillage methods and soil depths based on the seed number recovered and the seed longevity in soil. Field observation in the naturally reseeded CMV rice field showed that as many as 917～2,185 CMV seeds m-2 were found from 0～15cm soil depth in the rotary tillage and 250～10,105 CMV seeds in minimum tillage rice cultivation in autumn. The recovered seed germinated 25～33%, 23～43% but still had high percentage of hard seed having 64～72% and 51～77%. Field experiment showed that the CMV seedling still emerged even after 2 years of continuous destructive killing of emerged CMV plant by rotary tillage in naturally reseeded CMV-rice field, indicating that CMV seeds persistent at least two years in rice field.