벼 자동화 육묘시설에서 무상토 육묘 개발의 가능성올 제시하고자 깔판 종류에 따른 모의 생육특성과 생산비 절감효과에 대해 분석한 결과를 요약하면 다음과 같다. 깔판종류에 따른 10일묘의 초장은 처리간에 큰 차이를 나타내지 않았으나 육묘일수가 증가할수록 상토를 사용한 표준구가 무상토구보다 초장이 다소 큰 것으로 나타났으며, 신문지 5장을 깔판으로 이용하여 파종한 15일묘의 경우 표준구와 큰 차이가 없는 것으로 나타났다. 건물중의 경우 15일묘까지는 P.E 필름구를 제외하고 처리간에 큰 차이가 없었으나 파종 15일이후부터는 표준상토구, 신문지 5장, 골판지 순으로 건물중 증가 양상을 보였다. P.E 필름을 깔판으로 사용한 것에서는 다른 처리구에 비해 육묘일수 경과에 따른 건물중 증가가 크게 둔화되고 묘충실도도 가장 불량하였다. 깔판종류에 따른 매트 형성 정도는 신문지 5장과 골판지 처리구에서 가장 양호하였으며, P.E 필름에서는 거의 매트가 형성되지 않았다. 이상의 결과에서 신문지 5장을 깔판으로 이용하여 육묘하여도 시판상토를 이용한 표준구와 비슷한 건묘 육성이 가능한 것으로 조사되었다. 무상토 육묘에 소요되는 노동력과 경비를 관행중묘와 비교할 때 노동시간이 49.3%, 10a 당 묘생산비는 26.6% 절감되었다.

벼잎선충(線蟲)에 대(對)한 종자소독(種子消毒) 효과 및 본답(本畓)에서의 약제방제(藥劑防除) 체계(體系)를 구명(究明)코자 시험(試驗)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 벼잎선충(線蟲)에 대(對)한 종자소독용(種子消毒用) 살충제(殺蟲劑)로 메프유제(乳劑), 다수진유제(乳劑), 펜치온유제(乳劑)의 약효(藥效)가 양호(良好)하였다. 2. 기존(旣存) 종자소독용(種子消毒用) 살균제(殺菌劑)인 베노람수화제(水和劑), 티시엠유제(乳劑), Proaz유제(乳劑)와 살충제(殺蟲劑), 메프유제(乳劑), 펜치온유제(乳劑), 다수진유제(乳劑)를 각각(各各) 혼용(混用)하여 종자소독(種子消毒)을 하였을때에도 약효(藥效)가 우수(優秀)하였으며 약해(藥害)도 없었다. 3. 본답(本畓)에서의 벼잎선충(線蟲)에 대(對)한 방제체계(防除體系)로는 종자소독(種子消毒)+카보입제(粒劑) 토중처리(土中處理)와 종자소독(種子消毒)+카보입제(粒劑) 6월하순(月下旬) 수면처리(水面處理)가 효과적(效果的)이었다.

1. 벼이삭선충의 피해(被害)를 알기 위하여 경상남북도(慶尙南北道) 전라남도등(全羅南道等) 3개도(個道) 36개군(個郡) 111개면(個面)을 조사(調査)한 결과(結果) 피해경율(被害莖率)이 경남(慶南)에서는 창영군(昌寧郡)이 28.3%, 경북(慶北)에서는 영천군(永川郡)이 69.3%, 전남(全南)에서는 보성군(寶城郡)이 40.6% 로 각각 가장 높게 나타났다. 2. 벼이삭선충에 대(對)한 품종별(品種別) 피해경율(被害莖率)은 다수계(多收系) 품종(品種)에서는 원풍만 3.4%를 나타냈고 나머지 품종(品種)들은 전혀 white tip 증상(症狀)을 나타내지 않는 반면에 일반계(一般系)는 모두 의 피해경율(被害莖率)을 나타냈다. 종자내(種子內) 선충밀도는 다수계(多收系)나 일반계(一般系) 별차(別差)없이 같게 나타났으며 다수계(多收系)에서는 신광벼가 10gr당(當) 1,997마리, 일반계(一般系)에서는 동진벼가 10gr당(當) 1,023마리로서 각각(各各) 가장 높게 나타났다. 3. 침종전(浸種前)에 종자(種子)를 미박피구는 박피구에 비하여 선충분리율은 품종(品種)에 따라서 다소차이(多少差異)는 있으나 신선찰, 한강찰, 서광, 영풍, 밀양 23 호, 수정, 대청, 서남등(等) 8개품종(個品種)을 제외하고는 5% 이하(以下)의 낮은 분리율(分離率)을 나타냈다. 4. 온도별(溫度別) 침종시간(浸種時間)에 따른 선충분리율은 박피구와 미박피구 다같이 온도(溫度)가 높을수록 점차 분리율(分離率)이 높았으며 에서는 미박피구가 박피구보다 9일(日) 이후(以後)부터는 더 많이 분리(分離)되었다. 그리고 적산온도(積算溫度) 를 기준(基準)하여 보면 미박피구는 박피구에 비하여 에서는 6%, 에서 는 6.7%, 에서는 13.4%, 에서는 18.9% 분리(分離)되었다.

. 영남작물시험장, 호남작물시험장 및 충남농촌진흥원에서 분양받은 18개의 벼종자시료와 충남지역 일반농가에서 수확한 8개의 벼종자시료 등 모두 26개의 종자시료를 공시하여 표준습지법으로 조사하였던 바 21종의 균류가 검출되었으며, 벼 갈샐잎마름병균(Gerlachia oryzae)은 22개의 벼 종자시료에서 의 범위로 검출되었다. 2. 종자전염성 G. oryzae의 효과적인 검출방법을 찾기 위하여 표준습지법, 냉동습지법, 물한천법 등으로 비교 조사한 결과, 냉동습지법에서 검출율이 가장 높았다. 3. 벼종자의 각 부위를 무균적으로 분리하여 부위별로 G. oryzae의 감염여부를 표준습지법으로 조사한 결과, 벼 종자의 껍질에서 가장 많이 검출되었으며, 심하게 이병된 종자는 배유 및 종피 뿐 만 아니라 배에 까지 감염되어 있었다. 4. G. oryzae에 감염된 벼 종자를 파종하여 심하게 이병된 종자는 종자부패 및 묘입고를 일으켰으며, 약하게 이병된 종자는 초엽, 1엽, 2엽에 갈색의 병징감염을 초래하였다.

깨씨무늬병에 심하게 이병된 병팔굉 공시종자는 배양 일에 호영, 내외영 및 주병의 그리고 과피의 가 Helminthosporium oryzae에 감염 되어 있음을 보였다. 동균은 종립전면에 분생포자를 형성하였으며 배유의 약10여세포층까지 감염되어 있었으나 배조직에서는 검출되지 않았다. Fusarium moniliforme는 과피, 경유 및 배조직에서 검출되었으며 F. roseum, Trichoconis padwicku, Curvularia spp., Alternaria tenuis, Cladosporium cladosporoides 및 Phoma sp.는 이하의 영 및 과피에서 검출되었다. 배양일주일에 가 깨씨무늬 병징을 나타냈으며 는 외관상 건전하였다. 깨씨무늬병균은 감염된 종자의 제점으로부터 과피를 거쳐 시아및 유근에 전염 발병케 하였다.

본 실험은 침투성살충제 Fussol, Dimethoate, Metasystox 및 Dimecron을 벼, 보리 및 콩씨에 분의처리하였을 때 발아에 미치는 영향과 살충효과 및 그의 지속성을 알기 위해 실시하여 아래와 같은 결과를 얻었다. 1). 법씨는 Fussol처리에서 발아력을 완전히 잃었으며 Dimethoate 처이에서는 처리후 파종시까지 시간이 경과함에 따라 발아율이 크게 저하되었으나 Metasystox 와 Dimecron 처리에서는 발아저해가 비교적 적었다. 2) 보리씨는 Fussol처리에서 처리 후 1일 파종에서는 비교적 발아율이 높았으나 25일 파종에서는 발아력이 완전히 상실되었다. 그밖에 공시약제도 무처리에 비하여 약간의 발아저해가 있었으나 저장기문이 지나도 별로 발아력이 저하되지 않았다. 3) 콩씨에서는 처리후 1일 파종에서 공시약제 모두 비교적 좋은 발아율을 보였으나 Fussol, Dimethoate 및 Metasystox는 처리후 25일 파종에서 발아에 저해가 컸고 Dimecron 처리에서는 발아저해가 비교적 적었다. 4) 볍씨 처리에서 Dimethoate는 파종후 20일까지 끝동매미충에 대하여 살충력이 좋았으나 30일 에서의 살충력은 낮았다. 그밖에 약제처리에서는 살충력이 모두 낮았다. 5) 보리씨 처리에서 Dimethoate는 옥수수테두리진딧물에 대하여 비교적 살충효과가 좋았으나 다른 약제처리효과는 낮았다. 주당 평균 산난수는 무처리 13개에 대하여 Dimethoate 2개, Fussol 4개, Metasystox 6개, Dimecron 7개이었다. 6) 콩씨 처리에서는 파종후 9일까지 공시약제 모두 좋은 살충효과를 나타내었으며 18일 조사에서는 Dimethoate, Metasystox 및 Dimecron에서 비교적 중은 살충효과를 보였으나 Fussol만은 살충력이 무처리와 차리가 없었다. 7) 침투성살충제의 분의처리에 있어서 발아저해와 살충력 및 그의 지속기간은 약제의 종류, 종자의 종류, 처리후 파종시까지의 경과일수에 따라 큰 차이가 있는 것으로 본다

종자 산균제로써 Dithane M-45는 종래 사용해오던 유기수은제 보다 약간 우세한 살균력을 나타냈으며 적정농도는 1000ppm이였고, 적정시간은 4-6시간이었다. 그러나 Fusarium spp.에 대해서는 어느 농도에서도 흡족할만한 살균력을 나타내지 못하였다.

본 연구는 황토유황을 활용하여 벼 키다리병 발병을 최소화할 수 있는 최적 종자소독조 건을 선발하기 위해 수행되었다. 키다리병에 이병된 ‘신동진’ 품종 벼 종자를 공시하였고 황토유황 농도, 침지온도, 시간, 온탕여부를 구분하여 실내 및 온실검정을 통해 침지시간은 48시간, 침지농도는 1%로 최적 소독조건을 선발하였다. 그리고 모판과 포장시험을 수행하 여 온탕처리 후 20℃, 1% 황토유황에 48시간 침지 처리구와 30℃, 1% 황토유황에 48시간 단독 침지할 때 가장 효과가 높았다는 것을 확인하였고 위 처리조건으로 소독한 종자가 육 묘, 이앙, 출수기를 거치면서도 100%의 높은 방제효과가 유지되는 것을 확인할 수 있었다. 그러나 20℃에서 1% 황토유황으로 침지한 처리구에서는 포장에서 78.2%의 낮은 방제가를 보였다. 또한, 온탕소독만 수행한 처리구에서도 60℃, 10분간 충실히 수행될 경우 효과적인 벼 키다리병 방제가 가능함을 보여주었지만 온탕처리 후 황토유황으로 추가 침지함으로서 많은 양의 종자를 소독할 때 좀 더 나은 키다리병 방제 효과를 가져다 줄 수 있을 것으로 판단된다. 이상의 결과를 종합하여 볼 때 농가에서 온탕소독기와 종자소독기 둘 중 한가지 만 구비하더라도 황토유황을 이용하여 충분한 소독효과를 낼 수 있기 때문에 현장에서 보 다 쉽게 활용될 수 있을 것으로 판단되며 제조방법이 쉽고 비용이 적게 드는 황토유황의 특성상 농가의 경영비 절감효과도 클 것으로 기대된다.

Germination characteristics, seedling emergence, and early seedling growth of iron-coated rice seeds, cultivars Daebo and Samdeokbyeo, under different water depths were compared with those of non-coated seeds (control) and the results evaluated to obtain basic information for establishing stable seedlings in direct water seeding. The total germination percentage of the two seed treatments was similar, but iron-coated seeds had slightly faster germination and shorter mean germination time than non-coated seeds. Water absorption rates of iron-coated seeds were lower than that of non-coated seeds during seed germination. The germination percentage of the two iron-coated rice seed cultivars showed a significant decline of 15-22% after one year of storage under natural conditions. The seedling emergence percentage and uniformity of the two rice cultivars were significantly higher in the iron-coated seeds at 1-13 cm water depths but the percentage of floating seedlings was lower in iron-coated seeds than in non-coated seeds. The iron-coated seeds had a high seedling emergence percentage of 91.3-93.3% at all flooding depths whereas the non-coated seeds had a significantly low seedling emergence percentage of 57.7-71.7% at a water depth of 13 cm. Moreover, the shoot dry weight and seedling health score of iron-coated seeds were significantly higher than those of non-coated seeds, while root dry weights were similar in iron-coated and non-coated seeds, regardless of water depth. These results suggest that iron-coated seeds are more appropriate for stable seedling establishment in direct water seeding than are non-coated seeds.

We investigated the effect of silicate coating of rice seeds on bakanae disease incidence and the quality of seedlings raised in seedling boxes and transplanted into pots. The silicate-coated rice seed (SCS) was prepared as follows. Naturally infested rice seeds not previously subjected to any fungicidal treatment were dressed with a mixture of 25% silicic acid at pH 11 and 300-mesh zeolite powder at a ratio of 50 g dry seed - 9 mL silicic acid - 25 g zeolite powder. The following nursery conditions were provided : Early sowing, dense seeding in a glass house with mulching overnight and no artificial heating, which were the ideal conditions for determining the effect on the seed. The nursery plants were evaluated for Gibberella. fujikuroi infection or to determine the recovery to normal growth of infected nursery plants in the Wagner pot. Seedlings emerged 2-3 days earlier for the SCS than they did for the non-SCS control, while damping-off and bakanae disease incidence were remarkably reduced. Specifically, bakanae disease incidence in the SCS was limited to only 7.8% for 80 days after sowing, as compared to 91.6% of the non-SCS control. For the 45-days-old SCS nursery seedlings, the fresh weight was increased by 11% and was two times heavier, with only mild damage compared to that observed for non-SCS. Even after transplanting, SCS treatment contributed to a lower incidence of further infections and possibly to recovery of the seedlings to normal growth as compared to that observed in symptomatic plants in the pot. The active pathogenic macro-conidia and micro-conidia were considerably lower in the soil, root, and seedling sheath base of the SCS. In particular, the underdeveloped macro-conidia with straight oblong shape without intact septum were isolated in the SCS ; this phenotype is likely to be at a comparative etiological disadvantage when compared to that of typical active macro-conidia, which are slightly sickle-shaped with 3-7 intact septa. A active intact conidia with high inoculum potential were rarely observed in the tissue of the seedlings treated only in the SCS. We propose that promising result was likely achieved via inhibition of the development of intact pathogenic conidia, in concert with the aerobic, acidic conditions induced by the physiochemical characteristics associated with the air porosity of zeolite, alkalinity of silicate and the seed husk as a carbon source. In addition, the resistance of the healthy plants to pathogenic conidia was also important factor.

In this study, we analyzed seed storage proteins in order to investigate the main factors related to the eating quality of japonica and tongil-type rice varieties. Sensory evaluation was performed by a trained panel to assess the appearance (color and glossiness), flavor, taste, stickiness, texture, and overall score of nine japonica and three tongil-type rice cultivars. Moreover, the pattern of variation in rice storage proteins was examined by electrophoresis of protein extracts. The electrophoretic pattern of rice proteins showed 16.4 kDa albumin, 26.4 kDa globulin, 34-39 kDa and 21-22 kDa glutelin, and 14.3 kDa prolamin. In terms of storage protein, the varietal differences between japonica and tongil-type rice were found in albumin, globulin, and the α-1, and α-2 sub-units of acidic glutelin. Furthermore, the overall sensory evaluation score was observed to be positively correlated with albumin (0.495 ** ) and globulin (0.567 ** ), and negatively correlated with α-1 glutelin (-0.612 ** ). Therefore, the results indicated that albumin, globulin, and α-1 glutelin can affect the eating quality of japonica and tongil-type rice varieties, with the latter having lower eating quality than the former.

To investigate the effect of soluble silicate zeolite dressing of the rice against bakanae disease, field trial in reclaimed land and in vitro were carried out. The coated rice seeds (SCS) which were dressed with the mixture of 25% silicic acids (binder), and the zeolite (coating powder). In wet direct seeding, uniform scattering of rice seeds on the soil surface and the better seedling establishment were shown in SCS treatment plots. The incidence of bakanae disease began from the mid tillering stage toward the heading stage. Around heading stage, the ratio of infected tillers reached its highest point by 9.9% in non-SCS treatment plots. While, in SCS treatment plots, the ratio of infected tillers was no more than 0.01%. The vitality of the pathogenic fungi of bakanae disease in the SCS and non-SCS samples were assessed. Samples were incubated for one week keeping proper humidity at 30°C after inoculated with panicles of infected rice plants from experimental field plots. In non-SCS treatment, pinkish colonies were formed on the grain surface of panicle of infected plants, and mycelium, macro-conidia and micro-conidia were developed actively inside part of infected grain inoculated. While in SCS treatment, micro-conidia and mycelium were not survived and the growth of macro-conidia, mycelia were greatly inhibited and withered. Based on the results, it is concluded that the environmental friendly control of bakanae disease by use of SCS is possible and soluble silicate can be applied as agents for replacement of seed disinfection.

Seeds of colored rice generally have high anthocyanin and flavonoid content but some cultivars have low seed germination rate. This defect poses unstable seedling establishment in nursery bed. The seed gravity variations of 10 colored rice varieties and its effect on germination, seed soaking duration and their optimum seeding rates for seedling raising in machine transplanting were investigated in the experiment. Based on seed gravity distribution of the 7 black- and 3 red-colored rice varieties at three levels of seed gravity (1.0<, 1.0~1.06, 1.06>), the black colored seeds such as Josaengheugchal and Sinmyungheugchal had high amount of specific gravity of below 1.0 ranging from 86~ 96%, while they had only 3~13% of seeds in specific gravity above 1.06. Sintoheugmi, Heugjinju, Heugnam, Heugkwang had various mass of seeds, showing 29~44% for specific gravity of below 1.0, 24~39% for 1.0~1.06 and 25~45% for above 1.06. On the other hand, the red colored rice such as Hongjinju, Jeogjinju and Geonkanghongmi had high percentage of specific gravity of above 1.06 with 84~86% while they had only 9~12% of specific gravity below 1.0 similar to Ilmibyeo of noncolored rice. The black colored seed generally showed low germination percentage, slow germination speed and long mean germination time, and low water absorption rate as compared with seed of the red colored rice which was similar to those of Ilmibyeo used as a control cultivar. The black colored seeds took 2~4 days longer seed soaking duration than the red colored rice before germination. This was related to high seed amount of specific gravity below 1.0 in black colored rices. The high amount of seed gravity above 1.06 in the colored rice seeds was positively correlated with percentage of germination, germination speed and mean germination time, ripened grain ratio and water absorption. Seed gravity distribution effect were less pronounced between back- and red- colored seeds in seedling emergence. The black colored rice has slightly lower normal seedling emergence rate than the red colored rice and Ilmibyeo in the seedbed soil due to high percentage of ungerminated seed. Normal seedling emergence rate of the black colored rice in the seedbed was 75.2~82.2% for 10-day old seedling and 85.3~ 90.9% for 30-day old seedling which was lower by 4.5~ 8.0% and 0~3.3%, respectively, than the red colored rice. Based on the normal seedling number per tray of Ilmibyeo for seeding rate of 10-day and 30-day old seedlings, the recommended seeding rate of black colored rice is 200~ 220g seeds for the 10-day old seedling and 110~130g for the 30-day old seedling in transplanting rice while the seeding rate of the red colored rice was 220g seeds for the 10-day old seedling and 130g for the 30-day old seedling.

The influence of rainfall during the ripening stage on pre-harvest sprouting, seed viability, and seed quality was investigated in two Korean rice cultivars, Shindongjin and Hopum. When the rainfall was artificially treated in a greenhouse, HP started to pre-harvest sprouting at three days of rainfall treatment (DRT), but Shindongjin did not show pre-harvest sprouting at 40 DAH treatment and just 0.3~0.8% at 50 DAH, which was much lower than 15.3~ 25.8% of Hopum in the same treatment. After harvest, the seed germination of Hopum decreased about 10~25% compared to non-treated seeds, but that of Shindongjin decreased much little rate than that of Hopum. The seed longevity tested by accelerated aging decreased with prolonged rainfall period in both cultivars, but the varietal difference was clear; Shindongjin could withstand longer accelerated aging than Hopum. Shindongjin maintained its germination (>50%) ability after 15 days of accelerated aging regardless of the rainfall treatment period and time, but Hopum dropped below 50% germination ability after only 5 days of accelerated aging. In conclusion, rainfall during the ripening stage induced not only pre-harvest sprouting, but also reduced seed quality and longevity during storage, which varied between two cultivars.

1. 생산지에 따라 벼 종자의 수발아립률 차이가 컸던 호 품벼의 출아율과 발아율을 조사한 결과, 수발아율 8% 인 시료는 수발아율이 1%인 시료에 비해 발아율과 출 아율, 종자활력이 30% 낮았다. 2. 수발아율이 높은 시료는 수발아립의 변색 정도가 심 하고 미발아율과 부패율이 높았다. 수발아립은 배가 돌출하고, 변색된 배유와 곰팡이 감염이 관찰되었으며 배유의 1/2이상이 변색된 종자는 발아율이 매우 낮았다. 3. 종자의 발아 진행정도에 따라 현미의 변색이 심해졌 는데, 싹이 3 mm이상일 경우 배유의 1/2정도가 변색 되었다. 4. 발아 종자는 싹이 3 mm이상일 때부터 재발아율이 크 게 떨어졌으며 퇴화촉진처리 후 발아율의 감소가 더 컸다. 특히 퇴화촉진처리한 발아 종자는 싹이 2 mm부 터 종자활력이 크게 감소하였다. 결론적으로 수발아 발생이 심할수록 파종기 발아율과 출 아율의 감소가 크고, 수발아가 3 mm이상 발생하면 발아율 이 크게 저하될 것으로 생각된다. 또한 수발아는 동일 품종 과 동일 지역에서도 포장 간 차이가 크게 발생할 수 있으므 로 재배관리에 주의해야 한다.

The purpose of this study was to develop the cost-effective and efficiency seed longevity prediction method of rice (Oryza sativa L.) germplasm for viability monitoring. To find an optimum predicting method for rice seed longevity at genebank, an accelerated ageing (AA) test, a controlled deterioration (CD) test and a dry-heat treatment (DHT) were conducted to the four groups of rice germplasm based on ecotype, such as Indica, Japonica, Javanica and Tongil type. Among the three artificial aging treatments, the dry-heat treatment of 36 hours at 90°C is suggested as a routine predictive test method of rice germplasm longevity at a genebank. The distribution of germination rate on 3,066 accessions which conserved 26.5 years at 4°C showed similar trend with the result of distribution by dry-heat treatment at 90°C on 36 hours using 106 accessions of rice selected samples which composed four ecotype groups. The results show that the dry-heat treatment affect not only predicting the rice seed longevity but also determining effective interval for monitoring germination of rice germplasm in genebanks.

The purpose of this study was to know the seed longevity of rice (Oryza sativa L.) germplasm for effective viability monitoring. The longevity was determined via germination tests of 3,066 accessions of rice germplasm from the National Agrobiodiversity Center, Rural Development Administration, Korea. The rice germplasm accessions have been conserved at a mid-term storage (4°Csealed metal can on either sides for 25~26.5 years. The final germination percentages of 3,066 rice germplasm accessions of 6.5±1.0% seed moisture content with 94% initial germination stored at 4°C for 26.5 years declined to 47% while at -18°C for 25 years maintained high germinability as 93%. Germination time courses, which represent the average performance of rice ecotypes stored at 4°C and 30% RH, were fitted regression equation, to calculate the time at which germination characteristically declined to 50% (P50). These P50 values of Indica, Japonica, Javanica and Tongil type in rice were 39.9, 22.9, 25.4 and 31.8 years, respectively. The rice germplasm stored at 4°C could be clustered in 4 groups using quartile of final germination after 26.5 years storage. The seed longevity (P50) of each group was estimated by regression equation of changed germination percentages according to storage periods. The P50 values of group Ⅰ, group Ⅱ, group Ⅲ and group Ⅳ were 21.1, 23.6, 30.0 and 75.7 years.

It is well known that Dharial (Bangladesh origin and weedy rice line) has longer seed longevity than indica and japonica rice varieties. To study the genetic basis of seed longevity of Dharial, we developed 240 BC3F7 backcross recombinant inbred lines derived from the crosses between Dharial (a donor parent) and two korea rice accessions (recurrent parents) including Ilmi and Gopum, respectively. Among these lines, we selected two introgression lines with longer seed longevity and named them Ilmi-NIL and Gopum-NIL. Also, we developed an EMS-induced mutant line from Dharial which has shortened seed longevity, and named it Dharial-EMS. We performed re-sequencing of four rice accessions that are Dharial, Dharial-EMS, Ilmi-NIL, and Gopum-NIL. A total of 706×106 raw reads were generated which provided sequence data over 46x rice genome coverage per each accession. We did genome-wide variation analysis comparing produced re-sequencing data and the re-sequencing data of Ilmi from NABIC database with the Nipponbare reference sequence. By graphical analysis of SNP distribution in rice genome of the five accessions, we could select candidate chromosomal segments introgressed from Dharial in Ilmi-NIL and Gopum-NIL. The introgressed chromosomal segments were in seven regions in Ilmi-NIL and eight regions in Gopum-NIL, and four common introgressed regions between Ilmi-NIL and Gopum-NIL were identified. 2,758 SNPs between Dharial and Dharial-EMS were found in the introgressed regions. Also, we detected 450 genes including at least one SNP among these SNPs. This result will facilitate identification of genes and development of molecular markers for improvement of seed longevity.

Spatial- and temporal-specific expression patterns are primarily regulated at the transcriptional level by the promoter. Therefore, it is important to determine the binding motifs of transcription factors to understand the networks associated with embryogenesis. Here, we used a protein-binding microarray (PBM) to determine the binding motif of OsSMF1, which is a basic leucine zipper transcription factor that is involved in the regulation of rice seed maturation. OsSMF1 (previously called RISBZ1) is known to interact with GCN4 motifs (TGA(G/C)TCA) to regulate seed storage proteins (SSPs). In addition, OsSMF1 (also known as OsbZIP58) functions as a key regulator of starch synthesis in the rice seed. Quadruple 9-mer-based PBM (Q9-PBM) and electrophoretic mobility shift assay (EMSA) experiments revealed that OsSMF1 binds to the ACGT (CCACGT(C/G)), GCN4 (TGA(G/C)TCA), and GCN4-like (GGATGAC) motifs with Kd values of 0.3353 μM, 0.6458 μM, and 1.117 μM, respectively. We also identified 60 putative OsSMF1 target genes using a combination of data from expression microarrays and RiceArrayNet (RAN) analysis. Of these OsSMF1 target genes, 20, 22, and 17 genes contained ACGT, GCN4, and GCN4-like motifs within the 2-kb promoter region, respectively. In addition to known target genes, we also identified 35 potential OsSMF1 target genes that have not been previously described in immature seeds. We also confirmed that OsSMF1 directly regulates Os03g0168500 (thioredoxin-related protein), RPBF, NAC6, and two hypothetical proteins (Os12g0621600 and Os11g0582400) in vivo. This study suggests that OsSMF1 functions in a wide range of seed development processes with specific binding affinities for three DNA binding motifs

Rice (Oryza sativa L.) is important crop as a staple carbohydrate sources and was regarded as domesticated in Asia region. The seed dormancy is one of the domesticated traits, and this character allows that plants survive in various environment. The degree of dormancy have been targeted for controling in breeding program while weak dormancy cause pre-harvest sprouting contrary to the nonuniform seed germination by strong dormancy. In this study, we surveyed the variation of germiability in diverse rice genetic resources including japonica and indica ecotype. Overall, the degree of seed dormancy of rice germplasm was distinguished into four groups and admixed types; first group(G-1) included accessions revealing high germiability, the accessions of second group(G-2) acquired the high germiability by after-ripening process, third group(G-3)’s accessions showed high germiability after dormancy breaking process and the accessions of last group(G-4) maintained the low germiability in spite of the dormancy breaking process. Among the 51 japonica accessions G-1, G-2, G-3 and G-4 included 15, 15, 11 and 10 accessions, respectively, and among 40 indica accessions, G-1, G-2, G-3 and G-4 groups included 15, 15, 9 and 1 accessions, respectively. Based on these primary test, we plan to detail examine the seed germiability and survey the genetic factors affecting the degree of germiability in representative accessions of each group