Although chemical fertilizers have a quick effect and broad applicability to agricultural fields, they have caused many problems like increasing soil acidity or decreasing soil organic matters. Environmental-friendly agriculture has been attempted in various ways such as organic agriculture, natural farming, low input and sustainable agriculture. The common interest of all environmental-friendly systems is to decrease burden to agricultural environment by low input of agricultural labor and materials. This study was conducted to estimate overwintering capacity and genetic distance among Chinese Milk Vetch (Astragalus sinicus, CMV) collections based on morphological characteristics and AFLP (Amplified fragment length polymorphism) analysis. Furthermore, the effect of CMV as green manure was observed in mix-cultured paddy fields with rice, sesame and sweet-potato. An another objective of this study was also to compare the pattern of weed occurrence in paddy fields with or without CMV and different rice transplanting times. The CMV collected from Paju district in central region of Korea was successively occurring through self-reseeding without artificial management. However, there was no noticeable difference in growth habit between Paju native CMV and introduced CMV from China which is currently used in farm fields. On the basis of multi-dimensional scaling and tree analyses, there are no significant difference of agricultural growth characteristics among Paju and chinese collections only excepting leaf angle and root length. The flowering time of Gurye collection was fast for 1 week as compared to other collections. AFLP that was commonly used for plant classfication, was applied to exam the genetic variation of CMV collections. Total 579 PCR products and 336 polymorphic fragments were generated using 8 primer pairs.

Experiments were conducted to investigated the change of primary dormancy and viability of Chinese milk vetch(CMV) seed buried in soil both as seed and pod with seeds under CMV-rice cropping system during the period of 2007～2009. The freshly harvested CMV seed alone and pods with seeds were buried in rice field at 0, 5 and 10cm depths and determined change of seed dormancy and viability at one to three month intervals for 10 months. The CMV seed had high dormancy of 95%, showing only 4～5% germination at the beginning in June but the seed dormancy was gradually broken at rice harvest time in autumn, showing 25 to 35% for seed and 55 to 61% for pod with seeds. The viability loss was faster in the seed than in the pod with seeds regardless of depths of placement in the soil base on decayed seeds. Also the seed placed on the soil surface lost viability faster than the 5～10 burial depths. However, appreciable number of CMV seeds still remained at even 4 months after burial in soil. These results indicate that seed dormancy was enable CMV plant to regenerate naturally from the remained soil seed bank at rice harvest time in autumn.

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.

자운영 지속재배시 토양에 매몰된 종자의 휴면 및 발아특성을 조사하여 토양속 종자 동태를 구명하기 위해 자운영종자와 꼬투리의 토양매몰 깊이 및 기간별 휴면성과 종자활력 변화를 조사하고 또한 자운영 지속재배 포장에서 낙수후 자운영 종자의 토양속 분포 개수, 발아율 및 종자활력기간을 조사한 결과는 다음과 같다. 1. 자운영 종자 회수율은 종자 매몰 한달후부터 활력이 잃기 시작하여 낙수전 9월까지 52~65%, 낙수후 10월에는 급격히 떨어져 종자와 꼬투리 모두 30% 이하를 나타내었고, 꼬투리 매몰의 경우는 낙수전 9월까지 활력소실이 되지 않고 100%를 보였다. 2. 자운영 종자의 휴면은 수확당시는 95%로 높았으나 시간이 경과함에 따라 점차 파괴되어 9월에는 휴면율(경실율)이 종자는 12~22%, 꼬투리는 31~33%로 급격히 낮아졌고, 낙수후 10월에는 경실율이 종자는 2~8%, 꼬투리는 5~12%로 보다 더 낮아졌다. 3. 발아율은 토양 매몰전 종자는 4%로 낮았으나 토양에 120일간 매몰후 종자 및 꼬투리속 종자 발아율은 휴면이 타파되어 각각 21%~31%, 49~51%로 증가하였다. 4. 자운영 지속포장에서 9월 낙수후 토양속 잔존 자운영 종자는 로터리 부분경운이앙은 경운이앙보다 2.3~2.6배가 많았고, 자운영 종자분포 깊이는 로터리 경운은 0~15 cm 깊이에 고르게 분포되었으나 부분경운 이앙은 대부분의 종자가 5cm 이하 깊이에 분포하고 있었다. 5. 자운영 종자의 출아기간을 기준으로 한 토양 속에서 활력유지기간은 매몰 후 2년정도 인 것으로 조사되었다.

자운영 재배농가에 자운영 안정적 입모확보에 기초자료를 얻고자 자운영 지속재배와 매년파종시 입모 및 생육특성을 조사한 결과는 다음과 같다. 1. 자운영 지속재배포장에서 가을철 토양 속 자운영 종자는 이앙전 로타리는 토양표면에서 15 cm깊이까지 고루 분포한 반면, 부분경운 이앙시는 주로 10 cm깊이 이하에서 대부분 분포하였다. 2. 자운영 지속재배시 출아깊이는 부분경운 이앙시 1~3 cm. 로터리경운 이앙시 1~5 cm에서 출아가 되었다. 3. 자운영 지속재배는 표면에서 출아하는 매년파종 자운영보다 월동전 뿌리 길이가 깊어 월동율이 높고 논 정지 작업시 종자가 토양과 고루 혼합이 되어 입모균일도가 10.6~11.7% 가량 높아 입모수 확보가 유리하였다. 4. 자운영 지속재배시 건물생산성은 수분부족 및 저온 등기상환경이 불량 할 경우 매년파종보다 건물생산성은 높았으나 환경조건이 양호할 경우는 크게 차이가 없었다.

자운영 파종시 입모증진을 위한 기초 자료를 얻고자 수입 및 국내산 자운영 종자의 발아특성을 구명한 결과는 다음과 같다. 1. 수입 자운영 종자의 발아율은 79~95%로 수입 년도 및 수집지역에 따라 달랐다. 2. 종피가 검은색인 종자의 발아율은 녹색인 종자보다 발아율은 낮았으나 종자 활력은 비슷하였다. 3. 크기별로는 종자가 큰 것이 작은 종자보다 발아율은 약간 높았으나 종자활력은 크게 차이가 없어 작은 종자라도 상당한 발아력을 가졌다. 4. 광조건이 암조건보다 발아율이 7~9% 높았으나 통계적인 유의성은 없어 자운영 종자의 발아에 광의 영향은 크게 받지 않았다. 5. 수입자운영 종자는 휴면이 타파된 종자가 수입되기 때문에 상온보관시 1년후에는 발아율이 수입당시 보다 6%가 낮았고, 2년후에는 33~35%나 낮아 수입후 1년이 경과한 종자는 10당 추천 파종량 5 kg/10a 보다 1.1배, 2년 경과한 종자는 추천 파종량의 1.4배를 뿌려야 안전 입모수 확보가 가능할 것으로 사료된다. 6. 국내산 자운영 종자는 수확후 강한 기계적 휴면이 있어 상온에서 휴면이 타파되는데 5~6개월이 소요되기 때문에 중국 수입종자와 달리 상온에서 수확후 2년 3개월이 경과하여도 발아율이 72~82%로 수확 후 1년 3개월이 경과한 종자 발아율(73~85%)과 비슷하였다. 따라서 국내생산 자운영 종자의 경우 2년 3개월이 경과한 종자라도 10당 추천 파종량 5 kg/10a을 뿌리면 안전 입모수 확보가 가능할 것으로 사료된다.

자운영답 입모부족시 생초량 증진방법을 구명하고자 실시한 시험결과는 다음과 같다. 1. 3월초에 Sethoxydim 유제로 둑새풀을 일찍 방제시 방제가가 84%로 높았으나 처리시기가 늦을 수록 방제효과는 낮았다. 2. 둑새풀 방제후(처리 76일 후) 자운영 입모수는 처리전과 비슷하였고 가을철 재입모수도 처리전에 비해 2.2~2.6 배가 증가 하였으나 무처리는 둑새풀과 경합에 의해 자운영 입모수가 감소하였다. 3. 둑새풀 방제후 자운영 건물중은 자운영 피복도가 20%일때 63%, 50% 피복도일 때 164%가 증가하였고 질소함량으로는 12.3 kg, 16.4 kg/10a으로 표준질소시비량 9 kg/10a 보다 높았다. 4. 둑새풀 방제에 따른 쌀 수량은 기계이앙 및 부분경운 이앙 모두 무방제와 비슷하였다.

자운영 안전입모수 확보를 위한 벼 낙수시기를 기준 자운영 파종적기를 시험한 결과는 다음과 같다. 1. 벼 낙수 전 5일~ 낙수 후 5일 사이에 파종시 자운영 종자가 발아를 할 수 있는 충분한 토양수분이 있어 월동후 평균 입모수 및 월동율은 각각 530~670 개/m2 , 79.1~82.8% 로 높아 낙수 10일 이후 파종 보다 입모수 확보에 유리하였다. 2. 월동후 전생육기간 파종시기별 자운영 건물중도 낙수 전 5일~ 낙수후 5일에서 573~746kg /10a으로 높아 17.0~20.5kg /10a 질소를 생산할 수 있었다. 3. 자운영 종자를 너무 늦은 10월초나 낙수 10일이후에 뿌리면 자운영 종자가 출아를 하는데 온도가 낮고 수분이 부족하여 생육부진으로 월동율이 낮아 자운영 입모수가 부족하였다. 4. 낙수 10일전에 너무 일찍 파종해도 출아를 한 자운영이 습해를 받아 입모가 불량하였다. 5. 종자수량도 낙수 전 5일~ 낙수후 5일에 파종시 24.2~30.8kg /10a으로 높았으나 낙수후 10일 이후 파종은 종자 생산량도 19.4 kg/10a으로 낮았다. 따라서 자운영 안전 입모수 확보, 월동율, 건물생산성을 고려한 자운영 파종적기는 낙수전 5일(9월 20일)~ 낙수후 5일(9월 30일)이었다.

Freshly harvested seed of Chinese milk vetch (Astragalus sinicus L.; CMV) was strongly dormant because of hardseedness. Seeds of freshly harvested germinated only 8% while clipping the seed coat completely overcome the innate dormancy, which indicates inhibition of germination of the seed is mainly due to seed coat (87%). The dormant (intact) hard seeds did not imbibe water whereas the non-dormant (clipped) seeds took up rapidly. In natural environment condition, the hard seed coat dormancy was broken only after 5 months after seed harvest. To break such a strong seed coat dormancy, the chemical and heat treatments were effective. Concentrated sulfuric acid was more effective than dry heat and hot water treatments. Hot water treatment improved germination but the germination percentage was less than 41%. Treatments increased germination due to its effect on the seed coat integrity. A scanning electron microscope reveled that disruption of seed coat layers and subsequent development of numerous crack in the hilum region of the seed and on the seed coat surface of concentrated sulfuric acid treatment and formation of cracks in the dry heat treatments, respectively, were observed in the seed coat surface, which served as water entry points.

Seedling establishment, winter survival rate and dry mater production of chinese milk vetch(Astragalus sinicus L.) in natural reseeding practice was compared with annual seeding during the period of 2006-2007. Generally, practicing natural reseeding technology gives higher seedling stand than the annual seeding because of high seeding survival rate. The high seedling survival rate in naturally reseeded plant is related to the longer root length than that of the annual-seeded plant. In annual seeding, most of seeds stayed on the soil surface and root can not easily penetrate the soil. However, in natural reseeding technology, the seeds are incorporated into the soil during land preparation and they emerged from the soil at 0 to 5cm depths, thereby it has longer root length. This long root length contributes to greater ability to survive even low temperature and low soil moisture condition during winter. The dry matter production in natural seeding was higher than the annual seeding at the early growth stage but the later it was similar in both natural reseeding and annual seeding.

자운영 종자 생산을 위한 적정 수확시기를 결정하고자 개화 후 25일부터 5일 간격으로 40일까지 수확한 시험의 결과를 요약하면 아래와 같다. 1. 수확 시기별 자운영 종자 수량은 수확시기가 늦어질수록 증가하는 경향을 보였으며, 개화 후 35일이 가장 많았다. 2. 자운영 종자활력은 개화 후 35일 이후 수확한 것이 90%이상 높았으며 포장에서 자운영 지속재배를 위한 적정환원 시기는 개화 후 35일 이후였다. 3. 자운영 수확 후 발아율은 수확시기에 따른 차이가 인정되지 않았지만 저장기간이 길어질수록 늦게 수확한 것이 발아율이 높았다. 4. 발아율은 10~40 일 침종에서 증가하였으며, 40일 이상 침종시 발아율이 급격하게 떨어지는 경향을 보였다. 5, 경실율도 개화 후 수학시기가 늦을수록 증가하는 경향을 보였다. 이상의 결과로 자운영 종자 수확을 위한 적정 수확시기는 개화 후 35일이 적당할 것으로 사료된다.

The objective of this study was to investigate the variation of Chinese milk vetch(Astragalus sinicus L.; CMV) seed quality after flowering. We tagged individual open flowers of CMV at the day of maximum flowering(11 May) in Seoul, Korea. Seed samples were harvested serially at 15, 20, 25 and 30 days after flowering(DAF). To compare with dried seeds, non-dried seeds were tested immediately after harvest and the remaining seeds were placed at room temperature for 4 weeks. Seed length, 1000 seed weight, moisture content, germination rate(GR), mean germination time(MGT), germination speed(GS), germination performance index(GPI) and physical dormancy rate(PDR) were investigated. Seed length increased to 2.6 mm and 1000 seed weight reached up to 2.2 g until 25 DAF. Seed moisture content dramatically decreased from 20 to 25 DAF. Moisture content of non-dried seed(7.5%) was similar to that of dried seed(5.5%) at 25 DAF. The rate of seed viability reached up to 94% at 25 DAF. In case of dried seed, GR increased up to 39% at 25 DAF whereas GR of non-dried seed varied from 5 to 10%. GS and GPI of dried seed were significantly higher than those of non-dried seed since 25 DAF. PDR of dried seed has decreased since 20 DAF, whereas PDR of non-dried seed has increased. GR, GS and GPI increased as PDR decreased. Our results evidenced that PDR might be one of major factor in variation of seed quality, of which development was completed at 25 DAF.

자운영답에서 벼의 생육특성 등을 조사하여 벼-자운영 작부체계에 적합한 품종의 생리생태적 특성을 구명하고자 영남농업연구소 답작 포장에서 실시한 시험결과를 요약하면 다음과 같다. 1. 자운영 재배답은 무재배답에 비해 이앙 후 환원장애에 의한 초기 활착이 떨어졌으나, 풍미벼, 소비벼, 화영벼가 초장 및 개체군생장률 감소가 적은 편이었다. 2. 부위별 질소함량은 자운영 재배답이 무재배답에 비해 높았고, 반대로 질소흡수량은 단위면적당 건물중이 높았던 자운영 무재배답에서 높았다. 3. 자운영 재배답이 무재배답에 비해 수량이 낮았던 원인은 단위면적당 수수가 적었기 때문이다. 4. 수량에 영향을 미친 수량구성요소로써 자운영 재배답에서는 단위면적당 영화수가, 자운영 무재배답에서는 등숙율이 크게 작용하였다. 5. 쌀의 완전미율과 단백질 함량은 자운영 재배답이 자운영 무재배답에 비해 높게 나타났으며, 식미값은 유의적인 차이가 인정되지 않았다.

Chinese milk vetch (AstragaIus sinicus L.) is a biennial leguminous plant. Although this species is becoming a commongreen manure croP, Chinese milk vetch seed has a low germination rate due to low water permeability of the seed coat which islimiting fact

Overwintering capacity, closely related to winter hardiness, of Chinese milk vetch planted with different sowing times and sowing practices was investigated to improve the incorporation into cropping system in Korea. The tolerance to low temperature was evaluated with LT50 using leaf disc leaching method. Dry weight of CMV was reduced remarkably with delayed planting from Sep. 5 to Oct. 20. The differences in tolerance to freezing temperature were not conspicuous among CMV genotypes, however, the differences between genotype (collections at different regions) were due to the plant architecture, mainly to the leaf angle. The crouching genotype collected at central region of Korean peninsula, which showed excellent freezing tolerant, has planophile leaves. The feature of internal constituents of CMV genotypes did not show any noticeable differences with respect to the freezing tolerance which evaluated by leaf disc leaching experiment. To overcome the poor overwintering capacity, tolerant genotype should be developed by selection with considering the plant architecture. The reduction of CMV growth during overwintering period was ameliorated with furrow-sowing under late-sown condition, therefore, when the CMV is inevitably sown late after recommended time, the seeds should be sown on furrow to overcome the cold stress.

Germination and emergence habits of Chinese milk vetch (CMV) were examined to obtain the basic information for the effect of environmental conditions and cultural practices on the seedling density. Seed germination tests with different water potentials, temperatures, and soil and water depths showed the environmental effects on the characters related to seed germination in CMV. Imbibition under different temperatures reflects that initial velocity was rapid at higher temperature, however, the times to full imbibition were not different between 15 and 25~circ . The optimal germination temperature for CMV germination was ranged from 15 to 20 and the germination was highly affected by water potential of media at relatively high temperature above 20~circ . When the seeds were sown in flooded condition the germination was not proportionally affected by water depth. In addition, there was no correlation between water depth and oxygen concentration. The germination of seeds flooded by 2cm water depth were poorly germinated compared to other depths. Results indicated that the germination of submerged seeds was more highly influenced by flooding depth than the temperature, it was also affected more strongly at 10 than 20~circ . Emergence of CMV depending on the thickness of covered soil was poor when the soil layer was greater than 5cm. In the experiment with seeds collected between 22 days after flowering (OAF) and 52 DAF, the highest germination ability of CMV seeds was observed at 39 DAF and germinability was decreased subsequently as seeds became mature. The lower germinability may be due to the enhanced seed dormancy.

An experiment was carried out using pots to investigate the effects of Chinese milk vetch on the seedling establishment and growth in rice. Four irrigations with five-day intervals and three different levels of vetch straw were investigated. Significantly higher panicle numbers were obtained in vetch-treated pots. Vetch levels were non-treatment as checks, vetch with top removed, root plus shoot 7.5 ton/ha, and root plus shoot 3.0 ton/ha. The time for complete degradation of vetch straws was reduced from 10 days to 5 days as submerged time was delayed, and was affected by the amount of mulched vetch straws. As the mulched vetch amount increased, the time for a complete degradation was extended from 4 days to 12 days. Grain yield and its components were significantly affected by irrigation time and mulched vetch amount. Effectively controlled, lowered reduction damage from the degrading vetch straw, irrigation date and vetch amount were the most important factors for the improving of seedling establishment in direct-sown rice.