‘설백’은 조숙 내병 고품질 중간찰 계통을 육성할 목적으로 2000년 하계에 중간찰 품종인 수원460호에 조숙 내병 고품질 품종인 그루벼를 인공교배하여 2010년 육성된 조생 내도복 뽀얀 중간찰이다. ‘설백’은 보통기 보비재배에서 출수기는 평균 7월 29일로 ‘오대벼’보다 3일 빠른 조생종이다. ‘설백’의 간장은 60 cm이며, 주당수수는 13개, 수당립수는 81개이고, 천립중은 20.7 g으로 오대벼보다 가볍다. ‘설백’의 아밀로스함량은 10.0%로 중간찰이고 쌀 외관은 투명도가 5로 불투명해 보인다. ‘설백’은 위조에 강하고 불시출수가 잘 되지 않으며 성숙기에 하엽 노화가 느린 편이다. ‘설백’은 수발아에 강한 편이고, 내냉성은 ‘오대벼’와 비슷한 수준이다. 잎도열병에는 강한 저항성이고 흰잎마름병, 바이러스병 및 해충에는 약하다. 지역적응시험 보통기 보비재배에서 평균 쌀 수량이 4.96 MT/ha로 ‘오대벼’ 대비 92%의 수량성을 보였다. 재배적지는 중부평야지, 북부평야지, 중산간지, 남부고랭지 및 동북부해안지이다.

The amount of salt to make seed sorting solution of the specific gravity of 1.13 was reconsidered and determined as 3.8 kg salt in 18 L water, which is lower amount than currently used. Five rice cultivars were examined. Percent germination and seedling emergence were not similar. Seedling emergence rate of Japonica varieties, Nampyungbyeo and Daerypbyeo-1 were 87% and 95% under specific gravity of 1.13, respectively. Seedling emergence rate of Tongil type variety, Dasanbyeo was as high as 67% in specific gravity of 1.06. Seedling emergence rate of waxy rice, Hwasunchalbyeo and Aranghangchalbyeo were examined. Seedling emergence rate was 94% in both cultivars in specific gravity of 1.04. Seedling emergence rate was same in specific gravity of 1.08 which is generally used for selecting seed currently. Early growth (plant height, leaf number, and dry weight) were not significantly different by specific gravity within species. In all cultivars except waxy rice, highest seedling emergence rate was observed in specific gravity of 1.13 which is currently used for selection and decreased as specific gravity is lowed. However, considering total amount of seeds in each group of specific gravity, amount of seed in lower specific gravity group is relatively small and total seedling emergence rate within variety dose not show big difference. However, if seeds with low speicific gravity are produced due to the bad grain filling condition and consequently total seed content of low specific gravity increases, results will be differnt. Reduction in total growth and yield could occur. It will be important to comply with the seed sorting criterion of 1.13 for Japonica, 1.06 for Tongil, and 1.04 for waxy rice variety to ensure the maximum rice growth and yield.

The amount of salt to make seed sorting solution for rice of the specific gravity of 1.13 was reconsidered and determined as 3.8 kg salt in 18L water, which is lower amount than currently used. Various rice (Oryza sativa L.) cultivars were used to examine seed specific gravity effect on germination, seedling emergence, and early growth. Percent germination and seedling emergence were not different. Seedling emergence rate of Japonica varieties, Nampyungbyeo and Daerypbyeo-1 were 87% and 95% under specific gravity of 1.13, respectively. Seedling emergence rate of Tongil type variety, Dasanbyeo was as high as 67% in specific gravity of 1.06. Seedling emergence rate of waxy rice, Hwasunchalbyeo and Aranghangchalbyeo were examined. Seedling emergence rate was 94% in both cultivars in specific gravity of 1.04. Seedling emergence rate was same in specific gravity of 1.08 which is generally used for selecting seed currently. Early growth (plant height, leaf number, and dry weight) were not significantly different by specific gravity within species. In all cultivars except waxy rice, highest seedling emergence rate was observed in specific gravity of 1.13 which is currently used for selection and decreased as specific gravity is lowed. However, considering total amount of seeds in each group of specific gravity, amount of seed in lower specific gravity group is relatively small and total seedling emergence rate within variety dose not show big difference. As a result, it is considered that selecting seeds with water (larger than specific gravity of 1.00) instead of salt solution will not make large reduction in seedling emergence rate and have no effects in early growth.

Changing climate could be effect on the growth of soybean and seed yield, so we evaluated newly developed soy cultivars in the point of the physiological characteristics by changing temperature and light intensity in the phytotron. Two soy cultivars evaluated in three temperature levels (T1, 20/15; T2, 25/20; T3, 30/25oC at day/night) the pot experiment in phytotron between winter and spring in 2006 and spring and summer in 2007. Increased temperature from T1 to T2 and T2 to T3 enhanced crop growth parameters greatly and shortened growth duration and increased seed yield, however, grown in winter and spring enhanced too much plant height, so plant stems were very slim and weak and it resulted in the lodging problem. In this results we can estimate warming in Korean peninsular which might be increase temperature with low light intensity, so plant breeders and physiologists should be develop improved lodging resistance cultivars under low light intensity and high temperature.

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.

Environment-friendly soybean planting system has been being required in the upland field with high slope and heavy rain in summer season. Changes of weed amount and soybean yield by rye cover crop and conservation tillage were investigated. Soil-disturbing at conservation tillage before soybean planting increased numbers and dry weights of weeds germinated in late spring such as Echinochloa crusgalli P. Beauv (barnyardgrass) and Portulaca oleracea L. (common purslane) regardless of herbicide spray even though the weed, Chenopodium ficifolium Smith germinated before soil-disturbing were higher at non-disturbing soil. Higher weed amounts at plots of strip-tillage (30cm rototilling) compared to minimum tillage (10cm rototilling) was mainly due to the weed increase by soil-disturbing. Soybean yields at plots with rye cover crop, particularly early maturity rye cover crop, were lower than those at plots without rye cover crop, which was due to lower soybean seedling stand by heavy rye residue. More researches are required for the higher soybean yield at the minimum tillage with rye cover crop in which weed amounts were low.

Experiments were conducted with aims to (1) estimate the biomass yield potential, (2) characterize the biomass and digestible dry matter production, and (3) reveal the characteristic seedling establishment of a whole crop rice variety, Nogyangbyeo, in dry- and wet-seeded rice. Maximum aboveground total biomass of Nogyangbyeo was 18 t ha-1 in dry-seeded rice and 20 t ha-1 in wet-seeded rice. Biomass yield potential of Nogyangbyeo was lower than that of Dasanbyeo. Comparatively, Nogyangbyeo was straw-dependent and Dasanbyeo was grain-dependent for biomass accumulation. Percentage of digestible dry matter (DDM) was higher in panicles than straw. Digestible dry matter yield was determined mainly by biomass yield rather than DDM percentage. Number of seedling establishment in Nogyangbyeo was 73m-2 in dry-seeded rice and 109m-2 in wet-seeded rice. Poor seedling establishment of dry-seeded Nogyangbyeo in the field condition was the result of low seed germination under low temperature and poor seedling emergence by deep sowing. Low seedling emergence rate of Nogyangbyeo was attributed mainly to slow elongation growth by slow leaf development and partly to mesocotyl and 1st internode lengths, not to genetically defined leaf length. The slow elongation growth of Nogyangbyeo was the same even in the high daily mean temperature of 24~circC . Results suggest DDM yield in rice can be improved simply by increasing biomass and whole crop rice varieties should be adaptable to direct-seeding.

The study examined the effects of CO2 enrichment on growth of soybean (Glycine max). Two soybean varieties were used, Taekwang and Cheongja. 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 flowering stage. The plants were exposed to the two elevated CO2 levels of 500 and 700 ppm and the ambient level of 350 ppm. Results of the experiment showed that at the second-node trifoliate stage of the two varieties, the elevated CO2 increased plant height, leaf area and dry weight. The elevated CO2 also raised the photosynthetic rate of soybean as compared to the ambient level. From the beginning bloom stage to the full maturity stage of the two varieties, the elevated CO2 increased plant height, leaf area, seed weight and photosynthetic rate. The stomatal conductance and transpiration rate decreased on long days relative to short days of treatment. Through the entire stages, the elevated CO2 increased the water use efficiency of soybean plants because stomatal conductance and transpiration rate decreased at the elevated CO2 levels relative to the ambient level.

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.

This experiment was conducted to know the characteristics of kernel growth as affected by various temperature regimes during grain filling using the varieties Hwaseongbyeo, Ilpumbyeo and Chucheongbyeo. The rice plants tested were grown in the natural condition at 1/5000a Wagner pots until flowering. After flowering, the rice plants were moved to controlled temperature conditions in a phytotron. The minimum/maximum daily temperature in the phytotron was controlled by 12/18, 15/21, 18/24, 21/27, and 24/30~circC , respectively. The grain weights were measured every three days after treatment. The mean daily kernel growth rate during active grain filling period showed different responses among varieties under various temperature regimes. The kernel growth rate of Chucheongbyeo was seriously reduced as temperature regimes were decreased. However, that of Ilpumbyeo was not influenced so critically. Ilpumbyeo showed some advantages in grain filling under low temperature regimes compared to Chucheongbyeo. The lag phase in grain filling of Chucheongbyeo was the longest among tested varieties, followed by Hwaseongbyeo under daily mean temperature regime of 15~circC . Kernel weight of Ilpumbyeo increased fast in early grain filling phase under low temperature. This characteristic may be favorable for grain filling in temperate zone where the daily mean temperature is drastically dropped during grain filling period. Regression analysis with kernel growth rate and temperature showed the estimated critical low temperature for grain filling among varieties were 9~circC , 12~circC , 13~circC in Ilpumbyeo, Hwaseongbyeo and Chucheongbyeo, respectively. Under moderate temperature the duration of grain filling of Ilpumbyeo was longer than that of Chucheongbyeo. However, Under low temperature that of Ilpumbyeo was more favorable than Chucheongbyeo.

인ㆍ일 원녹교잡에 의해 육성된 신품종들의 정곡수량과 외견상 품질면에서 최고수량을 얻을 수 있는 적정수확시기를 구명하여 미곡의 간접증산에 기여하고져 품종 수원26004와 밀양2003를 공시하고 출수후 25 일 이후 55 일까지의 기간에 곡립의 건물중, 수분함량, 만립성, 제현율, 도정율, 동할미율, 심복백미율, 청미율 및 수미율의 경시적 변화를 조사하였으며, 그 결과는 다음과 같이 요약된다. 1. 곡립건물중은 수원 26004의 경우 출수후 30일 경, 밀양2003의 경우 출수후 35일 경에 최대에 이르렀고(생리적 성숙기), 그 후 출수후 55일까지 유의차가 없었다. 2. 곡립수분함량(Y, %)은 출수후 일수(X)와 수원26004의 경우 출수후 34일까지는 Y=68.245-1.33X, 그 이후는 Y=23.025-0.470X의 관계를 나타냈고, 밀양2003의 경우 출수후 25일 경까지는 Y=73.62-1.634X, 그 이후는 Y=33.59-0.570X의 관계를 나타냈으며, 품종간에 출수기, 등숙기상 및 생리적 성숙기가 달랐으며 건조속도의 전환기가 달랐음에도 불구하고 생리적 성숙기의 곡립수분함량은 두 품종 모두 28%이었다. 3. 곡립의 탈립성은 인ㆍ일교잡품종 수원26004와 밀양2003, 일본형 품종 진흥 모두 출수후 35 일 경부터 50일까지 수확시기에 따른 차이는 작았고, 품종간 차이가 컸으며. 탈립성 품종은 입당 90～100g, 비탈입성 품종은 입당 200～250g 정도의 탈립 저항성을 나타냈다. 4. 제현율 및 도정률은 두 품종 모두 출수후 35일부터 55일간에 큰 차이를 보이지 않았고, 동할미율과 수미율도 차이가 없었으나 청미율과 심복백미율은 생리적 성숙기부터 10일간 뚜렷이 감소하였다. 5. 이상의 수확기와 정곡수량 탈립성, 미질의 상관에서 나타난 수확적기는 생리적 성숙기 10일후 경이며, 이 시기의 곡립수분함량은 20% 정도이었다.9.0～46.9% 였고, 지방은 18.0～22.1%, 17.1～22.5% 및 16.7～23.6% 였다. 6. 종실의 평균 단백질함량은 5월 25일, 6월 10 및 6월 25일 파종이 각각 41.9, 42.7 및 43.1%로 파종기가 늦어짐에 따라서 약간 증가하였고 품종별로는 서천백묘, 백천, SS-74185 및 강림 등이 높고 수원8003, 수원8006 및 Hill이 낮았으며 나머지 품종은 중정도였다. 한편 지방함량은 각각 19.8, 19.3 및 19.2%로 파종기간 차가 작았고 품종별로는 수원8003, 수원8006, 동북대, 봉의 및 Williams 등이 높고 서천백일, 강림, 백천, 륙우003, 동산6001, 동산 7003 및 성안 등이 비교적 낮았고 기타 품종은 중정도였으며, 대체로 단백질함량이 높았던 품종들이 지방함량이 낮은 경향이었다. 7. 단백질과 지방함량기간의 상관은 5월 25일 파종에서 고도의 부의 상관(r=-0.5914)이나 6월10일과 6월 25일 상관에서 각각 r=-0.3038과 -0.2975로 부의 상관경향만을 보여 파종기에 따란 상관의 정도가 약간 달랐다. 8. 10a당 종실수량은 6월10일 파종(100%)에 비해 5월 25일 파종에서 104%로 그 착 적었으나, 6월 25일 파종에서는 76%로 만파에 의한 감수정도가 컸다. 품종별 수량은 5월 25일 파종에서 동산7003, Hill 및 Williams, 6월 10일 파종에서 동산 6001, 동산 7003, Williams 및 Hill 등이 대비품종인 광교에 비해 유의증수하였고, 6월 25일 파종에서는 동산 7003만이 증수하였다. 조생종서천백묘, H-25)은 어느 파종기에서나 가장 낮은 수량이였다. 9. 만파(6월 25일 파종)에 의한 감수정도를 기준하여 내만식성정도를 분류하면 광교, 수원8003, 동산69호, 성안, H-25 및 Harosoy 등은 컸고 수원8006, 수원900