To understand the heading habit of recently developed 20 Korean rice cultivars, rice plants in a phytotron were exposed to different temperature: 22.5~circC(day~;27~circC/night~;18~circC),~;27.5~circC(day~;32~circC/night~;23~circC) , and day-length conditions: 10, 12, 13, 14, 15 hours. Four rice cultivars (Sobibyeo, Juanbyeo, Ilpumbyeo and Shindongjinbyeo) showed relatively short Basic Vegetative Phase (BVP) of 17 to 18 days, while Dasanbyeo showed the longest (35 days) BVP, compared to other remaining 15 tested cultivars which exhibited 24 to 31 days of BVP. In this experiment, it was tried out to separate the eliminable vegetative phase into photosensitivity and thermo-sensitivity with two different pathways. Many tested cultivars, however, exhibited quite different responses under low temperature and / or long day-length conditions. Especially, Surabyeo and Juanbyeo were the most difficult cultivars to separate into photo- or thermo-sensitivity in that the eliminable vegetative phase of these two cultivars increased greatly only under low temperature (22.5~circC) and long day-length (15 hr.) conditions. Regarding the heading response to temperatures, tested cultivars could be categorized into 2 groups. In 1st group of rice cultivars, the eliminable vegetative phase decreased almost equally as the temperature changed from 20.0~circC~rightarrow22.5~circC~rightarrow25.0~circC~rightarrow27.5~circC . In contrast, the 2nd group of rice cultivars exhibited eliminable vegetative phase slowly decreasing when the temperature changed from 22.5~circC~rightarrow25.0~circC~rightarrow27.5~circC , but rapidly decreasing when the mean temperature changed from 20.0~circC~;to~;22.5~circC . All the cultivars belonged to 2nd group, the heading date would be very delayed if cool summer comes.

1) 현미 품위는 무경운 짚 피복 벼 작부체계(SMNTRCS)와 무경운 짚 피복 벼-자운영 작부체계(SMNTRVCS)가 관햄 벼-보리 작부체계(CRBCS)와 관행 벼 작부체계(CRCS)보다 좋은 경향을 나타내었다. 백미 품위는 SMN TRCS에서 가장 우수하였다. 2) Mg와 K의 함량은 SMNTRVCS에서 가장 높았으며 Na 함량과 Mg/K는 CRCS에서 가장 높게 나타났다. 3) 단백질함량은 SMNTRCS에서 가장 높았으며, SMNTRVCS, CRBCS 및 CRCS순으로 감소하였다. 아밀로스함량은 SMNTRVCS에서 다른 작부체계에 비해 높게 나타났다. 4) 알카리붕괴도는 1.2~% KOH농도에서 작부체계별 품종간 변이가 가장크게 나타났다. 모든 KOH농도에서 알카리붕괴도는 CRBCS에서 가장크게 나타났으며, CRCS가 가장 낮았다. 5) 양질미 생산을 위해서는 유기물 투입으로 질소시비량을 줄일 수 있는 작부 체계인 SMNTRCS 및 SMNTRVCS가 가장 유리 할 것으로 사료된다.

This study was conducted to examine the physiological and biochemical responses against UV-B radiation in the seedling of 15 different rice cultivars, having the different physiological sensitivities. Out of 15 rice cultivars tested, moderate and susceptible groups showed significant decreases in biomass and RGR (relative growth rate). Contents of total chlorophyll were reduced remarkedly by irradiation of UV-B. In all rice cultivars tested, the content of chlorophyll a was strongly decreased, while the contents of chlorophyll b were slightly reduced without showing clear different among three groups and 15 cultivars. Carotenoid content was largely reduced by UV-B radiation, whereas polyamine content was moderately increased. The contents of MDA (malondialdehyde) that reflect the level of lipid peroxidation of cell membranes were clearly increased by UV-B stress, showing higher content in susceptible cultivars than moderate and torelant cultivars. The physiological important parameters highly related to visible injury were leaf color, chlorophyll, carotenoid, and lipid peroxidation, whereas biomass and polyamines were not closely correlated. Based on this results, it was concluded that changes of visible injury and the contents of chlorophyll and MDA could be adequately applied and utilized as physiological indicators to UV-B radiation

A sequential planting method was developed to identify durable blast resistance in Korean rice cultivars. Two types of rice cultivars were investigated by a sequential planting after inoculation of mixed 26 rice blast isolates. Daesanbyeo and Gihobyeo, sh

The changes of the amino acid content including proline and protein content in response to NaCl treatment were investigated in between the salt-resistant variety CI5309 and salt-susceptible variety IR28 of rice. The amino acid contents such as -aminoapid

The DNA markers such as a STS marker, BpE18-3, and three RFLP markers, RG413, RG901, and G258 linked to Bph1 were employed to classify the source of resistance to brown planthopper (BHP) in rices. The markers, BpE18-3, RG413, and G258, showed distinct pol

Frequent occurrence of off-type plants in a given cultivar has been a serious problem in both breeder's and farmer's fields. An experiment was designed to examine the differences in rate of occurrence of off-type plants among Tongil-type cultivars (high yielding cultivars derived from indica/japonica hybridization) from which the possible cause of higher occurrence of off-type plant in a specific cultivar was deduced. Among five Tongil-type cultivars examined for morphological variant in the field, only one cultivar, Dasanbyeo, had off-type plants. When analyzed with SSR markers, off-type plants showed different band patterns from original cultivar, having several extra bands in addition to cultivar-specific band, suggesting that off-type plants were originated from Dasanbyeo, rather than originated from mixing or mishandling of seed materials with other cultivars. The possible cause of off-type occurrence seems to be natural pollination with other cuItivars adjacent to the original cultivar during seed multiplication. This was supported from the observation that self-crossed progeny of the off type plants showed a wide range of variation of agronomic traits which could not be observed when there was a smaller introduction of genes to the fixed germplasm as happened in the case of cultivar mutation. Another evidence supported this idea that Dasanbyeo showed much of difference in floral organ and behavior to other cultivar to be subjected to higher out-crossing than other cultivars examined.

This experiment was conducted to investigate the variation of nitrogen use efficiency, nitrogen uptake efficiency, physiological utilization efficiency and their relationships with growth characteristics in the 28 Korean rice cultivars. Nitrogen use efficiency of 28 rice cultivars was 47.74, nitrogen uptake efficiency was 0.71, and physiological utilization efficiency was 68.76 in average. Nitrogen use efficiency of rice cultivars had low variation ranged from 44.09 to 51.91, but nitrogen uptake efficiency were relatively high variation from 0.51 to 0.90, and physiological utilization efficiency was from 51.71 to 94.26. The high efficient group in nitrogen uptake efficiency whose value was calculated above 0.80 included Daeanbyeo, Seojinbyeo, Ansungbyeo, Dongjinbyeo, and Hwaanbyeo, while the low efficient group with below 0.60 was Kwanganbyeo, Sampyeongbyeo, Soorabyeo, and Hwasungbyeo. Hwasungbyeo, Sampyeongbyeo, Soorabyeo for physiological utilization efficiency were more efficient cultivars, while Daeanbyeo, Seojinbyeo, Ansungbyeo were less efficient cultivars. Nitrogen uptake efficiency had positive correlation coefficients between dry matter weight of plant (0.842** ), leaf area index (0.761** ), and leaf nitrogen content (0.599** ), respectively. Therefore, the dry matter weight of rice plant and leaf area index was important characters to evaluate nitrogen uptake efficiency in rice cultivars. Also, more efficient cultivar in nitrogen uptake had higher chlorophyll meter value, which was appeared dark green color.

최근 비교적 재배면적이 넓은 일미벼, 대산벼, 동안벼와 이들의 모본들로 구성된 23품종의 유전적 다양성을 조사한 결과를 요약하면 다음과 같다. 1. 1999년에서 2001년에 잎도열병과 이삭도열병이 심하게 발병한 일미벼. 대산벼, 동안벼는 밀양95호를 모본으로 육성되었다. 2. 밀양95호를 모본으로 하는 품종들에 대해 SSR 마커를 이용하여 유전적 다양성을 조사한 결과 57개 유전자좌위에서 170개(평균 3.0개)의 alleles이 관찰되었으며 대립유전자수는 2개에서 7개까지 다양하였다. 특히, RM249, RM206, OSR20은 6개 이상의 대립유전자를 가져 근연의 자포니카 벼품종간의 유전적 다양성 평가에 유용하게 이용될 수 있을 것으로 판단된다. 3.증폭된 밴드의 유무를 바탕으로 품종간 유전적 거리를 산출하여 군집분석을 실시한 결과 크게 4개의 군으로 나뉘었으며 일미벼, 대산벼, 동안벼는 모본인 밀양95호와 유전적 배경이 매우 유사하였다. 4. 같은 계보상의 품종들에 대해 도열병 저항성 유전자 인근의 마커를 이용한 유전적 다양성 분석결과가 계보도와 일치하여 이들 품종들의 저항성 유전자형 또한 유사할 것으로 추청할 수 있었다. 5. 조사품종의 계보상의 allele 전이를 분석한 결과 11번 염색체의 RM254의 3번째 allele과 12번 염색체의 OSR32의 2번째 allele이 밀양95호로부터 계속 전이되었음을 알 수 있었으며 이들 alleles의 도열병 이병화와의 연관성 여부는 추후에 검토가 이루어져야할 것이다.

Typhoon "MAEMI", happened in September 2003, hit the great damage to Gyeongnam province area. Especially, rice plant was lodged or severe leaf damage was caused. This study was conducted to find out the extents of leaf damage among different rice cultivars, and to evaluate rice yield and eating quality due to leaf damage after typhoon. Rice cultivars torn off over half of the flag leaf length (FLL) were one medium-late maturing cultivar (Donginl), medium maturing cultivar (Yeonganbyeo), eight early maturing cultivars (Samcheonbyeo, Jounghwnbyeo, Munjangbyeo, Taebongbyeo, Odaebyeo, Samhaegbyeo, Sobaegbyeo, Sinunbongbyeo), two long-il type cultivars (Samgangbyeo, Namcheonbyeo), and three special use cultivars (Heukseonchalbyeo, Jinbuchalbyeo, Yangjobyeo). Cultivars torn off below 1/10 FLL were eight medium-late maturing cultivars (Chucheongbyeo, Daecheongbyeo, Saechu cheongbyeo, Donganbyeo, Daeyabyeo, Hwamyeongbyeo, 방eongsanbyeo, Dongjinbyeo) and two medium maturing cultivays (Donghaebyeo, Gumobyeo2). The rest cultivars were tore off by 1/10∼1/2 ELL. In yield components, the longer was flag leaf damage, the lower was ripened grain ratio, grain weight and brown/rough rice ratio, which was severly impacted to late than to ordinary season cultivation. However, rice yield did not decrease up to tearing by 1/10 ELL. Head rice ratio decreased from flag leaf tearing over 1/10 ELL in late season cultivation. The longer was flag leaf damage, the lower was eating quality, which could not show significantly different.