Drought caused by global climate change is one of serious problems for rice cultivation. However, it was little reported the impact of drought on rice cultivation in Korea. In here, to assess impact of drought on rice varieties in Korean climate condition, growth characteristics and yield components of rice were compared on irrigated and partially irrigated rice paddy field. First, we have chosen 11 rice varieties including ‘Saeilmi’ and ‘Shindongjin’ which are widely cultivated in Korea. For partially irrigated rice paddy treatment, we have withheld irrigation from 25 days after transplanting and water supply was totally dependent on rainfall for rice cultivation. When we examined early plant height and tiller number of these varieties on partially irrigated rice paddy were reduced 1.6% to 18.4% and 10.4% to 33.1%, respectively, and these reduction rate were highly correlated with yield loss in our experimental conditions. Among rice yield components, panicle number was decreased 10.5% to 30.1% according to rice varieties and reduced panicle number was highly correlated with yield loss. Grain number per panicle, grain filling rate and 1,000 seeds weight did not have correlation with yield loss of rice varieties. These result means that growth stage, especially the tillering stage, is seriously affected by drought on rice cultivation in Korea. And we suggest that ‘Saeilmi’, ‘Ilmi’ and ‘Ilpum’ are good for rice cultivation on drought prone rice field in Korea.

This study was conducted to measure the effect of PE film mulching and irrigation methods on the growth, yield and antioxidant activity of potatoes tubers, in order to examine the possibility of cultivating potatoes in winter season in vinyl greenhouse on the reclaimed tidal land with weak ground inside the sea wall currently completed. The test was conducted on the sandy loam soil (Munpo series), and its salt concentration was 0.42% at the time of planting. The emergence speed per kind of PE film mulching was in the order of black > coloration > transparent > green color, with the black color showing the fastest speed. The temperature change during a day per kind of PE film mulching was in the order of transparent > coloration > green > black color. As for the salt concentration in the soil for each different way of water management, the salt concentration in the treatment of drip irrigation with 1 week interval was lower than that drip irrigation with 2 weeks interval. As for the growth of above-aerial part, plant length was higher, number of tiller and leaves were more and dry weight of above-aerial part was larger in the treatment of drip irrigaton with 1 week interval than drip irrigation with 2 weeks interval. As for the yield of potatoes depending on were higher with pear color vinyl treatment. each way of water management, the yield in the treatment of drip irrigation with 1 week interval was more than drip irrigation with 2 weeks interval. The yield for each different kind of PE film mulching in the weekly drip-irrigation management section was in the order of transparent ≥ black ≥ coloration ≥ green color. In both of total phenol content and DPPH free radical activity experiments, the content and activity

우수한 사료자원으로 평가되는 케나프의 생산단가를 낮 추기 위하여 새만금 간척지 시험포에서 염농도 단계별 생육 및 수량을 관찰한 결과 케나프는 중·상정도의 내염성을 보 유한 작물로 평가할 수 있으며 충분한 제염이 이루어진다고 하면 간척지에서의 재배 가능성도 충분할 것으로 평가할 수 있었다. 염농도별 케나프의 발아력을 조사한 결과 토양 염 농도가 4.0 dS/m (=0.26%) 일 때 84%이던 케나프 발아율 이 5.0 dS/m (=0.32%) 에서는 18%로 급격히 떨어졌으며 6.0 dS/m (=0.39%) 에서는 발아율이 10%를 넘지 못하였다. 또한 생육 상황도 토양 염농도에 비례하여 급격히 떨어졌는 데 케나프는 줄기직경을 2.6 cm 이상으로 유지할 수 있을 경우 엽수가 유의할 수준으로 늘어나고 줄기부분에 대한 상 대적 무게비율이 증가하는 결과를 얻을 수 있었다. 이는 잎 의 분열을 촉진시킬 수 있는 충분한 생장량 확보가 줄기직 경 2.6 cm 이상에서부터 가능하다는 것을 의미하는데 새만 금에서는 토양 염농도 4.0 dS/m (=0.26%) 이하에서는 케나 프의 줄기직경을 2.6 cm 이상으로 유지하는 것이 가능하였 으나 염농도가 5.0 dS/m (=0.32%)를 넘어서게 되면 줄기직 경이 2.0 cm 이하로 엽수도 20~46% 감소하였다. 생육장해는 파종 후 1개월 경과부터 본격적으로 나타나기 시작하였 는데 엽 정단이 고사하고 주변 잎 들이 급격하게 황화 낙엽 되는 현상이 발생하였다. 케나프의 토양 염농도에 대한 수 량성을 분석한 결과 토양 염농도 4.0 dS/m (=0.26%) 까지 는 비간척지에 비해 수량이 최대 19% 하락하였으나 염농도간 차이는 크지 않았다. 그러나 토양 염농도가 4.0 dS/m (=0.26%) 를 넘어서는 5.0 dS/m (=0.32%) 에서는 비간척지의 51% 수준을 유지하는데 그쳤으며 토양 염농도 4.0 dS/m (=0.26%) 일 때의 수량에 비해서도 38% 감소하였다. 통계분석을 통 하여 간척지에서 수량성 감소를 80% 이내로 유지 할 수 있 는 토양 염농도를 산출해본 결과 토양 염농도가 4.2 dS/m 이내로 유지될 경우 케나프의 생산성은 80% 이상을 유지할 수 있었다.

This study conducted experiments on the reclaimed land of Saemangeum located in Jeongrabuk-do in order to gain basic information about growth characteristics and yield ability according to soil salinity. Having soil excluding salt as a control group, this study adjusted the specimens’ soil salinity to level 4 and then planted four varieties including Ilmichal Corn to investigate the growth or grain yield according to salinity. About the corn establishment rate according to soil salinity, over 97% up to 3.2 dS m-1 was established, and then, it was reduced gradually according to the increase of concentration. According to the salt concentration of soil more required growth duration from seeding to heading comparing to non-treatment salt was delayed, at 1.6 dS m-1, two days were delayed, at 3.2 dS m-1, four to six days were delayed differently by varieties, and at 4.8 dS m-1, six to 10 days were delayed. About the plant fresh weight according to soil salinity, Chalok 4 and Eolrukchal indicated 93%~97% or so compared with the salt-free one at 1.6 dS m-1, and Chalok No. 4 showed 79% at the salinity of 3.2 dS m-1, too, and it was a relatively higher growth percentage than those of the other varieties. In terms of dried seed weight according to soil salinity, compared with the corns cultivated in the control group, averagely 12.1% was lowered at the time of cultivation at 1.6 dS m-1, and 3.2 dS m-1 40% was lowered, and about 70% was lowered at 4.8 dS m-1. According to the result of examining the point of time that dried seed start to reduce due to soil salinity with the regression equation, soil salinity which starts the reduction of grain weight is 1.67 dS m-1~2.18 dS m-1, and it differs by varieties, and EC of 50% that the yield reduces in half is 2.96 dS m-1 ~4.45 dS m-1. And the degree of influence on each of the growth factors according to soil salinity is founded to be in the order of establishment rate<plant length=the ear’s fresh weight<the plant fresh weight<yield.

본 연구에서는 새만금 지역에 조성된 신간척지 포장에서 담수와 하작물 재배처리가 제염 및 후작으로 재배한 청보리의 생육 및 수량에 미치는 영향을 조사 분석하여, 신간척지포장의 조기제염 기술을 개발하고자 하였다.1. 담수기간별 하작물 재배후 청보리 입모를 보면 무담수에서 m2당 216개로 입모율 25%, 1개월 담수 43%, 2개월과 3개월 담수 58%, 벼 재배구는 60% 이었다.2. 토양염농도는 청보리 파종 시에 무담수 처리에서 0.50%로 높았고, 그 외 담수처리에서는 0.2% 이내로 낮았으며, 생육 중기까지는 높아지다가 생육후기에는 파종시의 수준과 비슷하였다.3. 초장과 간장은 담수기간이 길수록 많았으며, 경수도에서 504%, 벼 재배에서는 536% 증수하였다.5. 사료가치는 담수 1개월은 단백질함량과 섬유소함량이낮게 나타났고, 담수 3개월은 벼 재배구와 사료가치면에서 비슷한 결과를 보였다.이상의 결과를 종합하여 볼 때, 새로 조성된 간척지(사양토)에서 제염을 목적으로 담수할 경우 3개월 이상 담수하거나 벼를 재배하여 제염을 하고 밭작물(청보리)을 재배하여야 어느 정도 수량을 얻을 수 있을 것으로 판단된다.많아지는 경향이었다.4. 수량은 무담수에서는 극히 적었으며, 담수기간이 길수록 수량은 급격히 증가하여, 무담수 대비 3개월 담수에서 504%, 벼 재배에서는 536% 증수하였다. 5. 사료가치는 담수 1개월은 단백질함량과 섬유소함량이낮게 나타났고, 담수 3개월은 벼 재배구와 사료가치면에서 비슷한 결과를 보였다.이상의 결과를 종합하여 볼 때, 새로 조성된 간척지(사양토)에서 제염을 목적으로 담수할 경우 3개월 이상 담수하거나 벼를 재배하여 제염을 하고 밭작물(청보리)을 재배하여야 어느 정도 수량을 얻을 수 있을 것으로 판단된다.

제염중인 간척지 토양에 감자재배 가능성을 검토코자 새만금 간척지 토양을 대조구를 포함한 4수준의 염농도로 조정하여 충진한 포트에 5개의 감자 품종을 식재하여 시험을수행하였다.1. 토양염농도에 따른 감자 입모는 4.8 dS m-1까지 결주없이 균일하게 입모 되었다. 염농도별 감자 출현소요일수는 숙전토양 비하여 1.6 dS m-1에서는 품종에 따라 3-4일이 지연되었고, 3.2 dS m-1에서는 6-10일이,4.8 dS m-1에서는 7-13일이 지연되었다.2. 토양염농도에 따른 경수는 숙전토양에 비해 1.6 dS m-1에서는 품종에 따라 각각 14%-58%가 감소되었으며,이후 토양염농도가 높아질수록 감소가 심했다. 초장은주당 경수가 적었을 때 커지는 경향으로 염농도보다경수의 영향을 더 크게 받았다.3. 괴경 수량은 대조구 대비 1.6 dS m-1일때 33.7%, 3.2 dS m-1일때 59.5%, 4.8 dS m-1에서는 79.3% 가 감소되었다.4. 회귀곡선을 이용하여 수량의 감소가 시작되는 염농도를 분석한 결과 추동은 1.2 dS m-1, 추백은 1.8 dS m-1,추강과 추영은 1.9 dS m-1, 그리고 수미는 2.0 dS m-1이었고, 수량의 50%가 감소되는 염농도는 추백은 2.4 dS m-1,추동 2.45 dS m-1, 추강 2.81 dS m-1, 추영 3.03 dS m-1,수미는 3.29 dS m-1였다.이상의 결과를 종합하였을 때 간척지 재배에 적당한 감자품종은 수미로 판단된다.

This study was conducted to examine the appropriate transplanting date of the top-quality rice variety, Unkwangbyeo, in Honam plain area. The results obtained from 2006 to 2007 in Iksan are as follows. The number of panicle per m2 increased as the transplanting date became late and the number of grain per m2 was the highest in the plot of which the transplanting date was June 15. Percent ripened grain increased as the transplanting date became late until June 15, however, it decreased in the plot of which the transplanting date was June 30. Imperfect grain increased as the transplanting date became early due to the occurrence of immature rice and cracked rice. Protein content increased as the transplanting date became late, but didn't show statistical significance. Toyo texture increased as the transplanting date became late. Rice yield and the head rice yield increased as the transplanting date became late until June 15, however, they decreased in the plot of which the transplanting date was June 30. Even though the rice price was high in early transplanting cultivation, gross profit was the highest in June 15 transplanting since the rice yield increased as the transplanting date became late until June 15. Considering the yield, rice quality and profit, the most appropriate transplanting date of Unkwangbyeo in Honam plain area is the middle of June.

This study was carried out to develop rice growth model when cultivate early maturing rice cultivar, Unkwangbyeo, in Honam plain area. To confirm leaf emergence rate and variation of heading date, we transplanted 15 day and 30 day old seedling on May 1, May 15, May 31, June 15, June 30, respectively. The growth duration between transplanting and completion of leaf emergence on main culm were 50.1~78.3 days in 2007 and 47.5~74.7 days in 2008. Growth duration diminished gradually as transplanting time delayed, but the difference of growth duration by transplanting time were more bigger than that of seedling day. The emerged leaf number after transplanting on main culm were 8.9~10.9 in 2007 and 8.4~10.9, respectively. The emerged leaf number diminished as transplanting time delayed, but the difference of emerged leaf number by transplanting time were more bigger than that of seedling day. The cumulative temperature between transplanting and completion of leaf emergence on main culm were 1,281~1,650℃ in 2007 and 1216~1560℃ in 2008. The solar radiation between transplanting time and completion of leaf emergence on main culm were 709~1,245MJ/㎡ in 2007 and 722~1,220 MJ/㎡ in 2008. The sunshine hours between transplanting time and completion of leaf emergence on main culm 234~433 hours and 238~431 hours, respectively.

This study was carried out to attain the basic data which will be used in the selection of adaptable varieties in honam plain area for the production of high quality rice. 12 varieties including Unkwang, Hwayeoung and Nampyeong were tested in southern plain area, Iksan. The number of panicles per ㎡ was the highest in Hopyeong, the lowest in Sindongjin, and that of other varieties was around 350. The mean percentage of effective tillers was the highest in early maturing varieties, the lowest in Ilpum, Nampyeong and Junam, and that of other varieties was around 75%. The number of total seeds was the highest in Hopyeong which had the high number of panicle per ㎡ and in Dongjin 1 which had the high number of seeds per panicle. That of Hwayeong, Sindongjin and Odae was the lowest, respectively. Percent ripened grain of the early maturing varieties was lower than the medium maturing and medium-late maturing varieties showing 93% in Hwayeong, Ilmi and Samkwang which is the highest, and 83% in Unkwang which is the lowest. Head rice ratio was high in Nampyeong, Hwayeong and Ilmi, and low in early maturing varieties, Unkwang and Odae. Protein content was high in Odae, Hwayeong and Nampyeong, and low in Sindongjin, Samkwang and Pyeongan. The rice yield was high in Sindongjin, Unkwang, Ilmi and Dongjin 1 showing more than 500kg/10a, while the head rice yield was high in Nampyeong, Dongjin1 and Sindongjin, and low in Ilpum and Odae.

Clay-coated rice seeds (clay-coated seeds A and B) were directly sown on dry paddy and their growth and yield were compared with the normal drill-sown seeds on dry flat paddy. In clay-coated seeds, germination was 1 day earlier and the emergence rate was higher up to 5% than that of normal drill-sown seeds. But the apparent number of seedling stand per m2 was lower than that of normal drill-sown seeds, which is due to the smaller amount of seeding in clay-coated seeds. At the early growth stage, the plant height of clay-coated seeds A was taller than that of drill-sown seeds, while the plant height of clay-coated seeds B was 0.7 cm shorter than that of drill-sown seeds. At the late growth stage, however, the difference was insignificant in both cases. The maximum tillering stage was 10 days earlier in drill-sown seeds. Lodging index was the lowest in clay-coated seeds B and there was no difference between clay-coated seeds A and drill-sown seeds. The ratio of stem base weight, culm diameter and culm wall thickness were higher in clay-coated seeds, while the lower internodes (4th, 5th and 6th) length was shorter in claycoated seeds than in drill-sown seeds. In clay-coated seeds, the number of panicle per m2 was smaller, while the number of spikelet per panicle was a little larger than in drill-sown seeds. The rate of ripened grain and brown rice 1,000 grain weight were lower in the clay-coated seeds, thus the yield was 98~99% level of drill-sown seeds. Considering that the amount of seeding in clay-coated seeds was two-thirds of that in drill-sown seeds, it is expected that clay coating method could become an additional technique for direct seeding cultivation.

This study was conducted to evaluate the drought tolerance of Japonica and Indica rice cultivars during germinating and seedling stages by using the polyethylene glycol (PEG) solution. Each 5 cultivars of Japonica and Indica were cultured from 14 days after seeding(DAS) to 21 DAS using the PEG solution in a moderate water potential (-0.63 MPa). The lengths of radicle and plumule during the germinating stage were inhibitied by the PEG treatment to about 50% and 85%, respectively. The application of PEG to the seedling of two rice types caused to inhibit the plant height and leaf age about 23 % and 10%, respectively. Shoot and root dry weights by PEG treatment were inhibited more severely in Japonica than those in Indica. The difference on delaying of leaf area expansion between both rice types was not found with treatment of PEG, while the leaf color was increased in both Japonica and Indica by 19.9% and 9.2%, respectively. The average photosynthetic ability was inhibited more in Japonica to 36.0% than did Indica to 27.9%. The stomatal conductance was severely affected by PEG treatment, and the degree was varied in both rice types, ranged with 80-85% in Japonica and 29.3-81.6% in Indica. These results indicate there is little relationship between seed germination and seedling growth under the stress of low water potential.

Soil moisture condition is an important limiting factor in growth and yield in rice culture. The purpose of this study was to compare the influence on the growth, yield and Quality of rice subjected to soil moisture stress (SMS) at different growth stages. Ajaponica rice cultivar, Dongjinbyeo, was cultured under flooded conditions in a plastic container filled with silty loam soil. The container was subjected to SMS until the initial wilting point (IWP) coincided with about 10% in soil moisture content and about-200 kPa in soil matric potential, and was then irrigated again, at 6 and 5 of main growth stage in 1996 and 1997, respectively. At maturity, the plant height, tiller number, leaf area and top dry weight were decreased more in SMS treatments at the early stage than the late stage. The averaged yield index of SMS to control in both years was lowest at meiosis (62.5%), which primarily resulted from lower percent ripened grain and 1,000 grain weight, and second＇ reduced the spikelet number per panicle and panicle number per hill, and followed at tillering stage (68.5%) which resulted from the lower production in tiller number and top dry matter during and after SMS treatment. The percent-age of read rice in SMS plants varied with the treatment stage as order of lower at meiosis (44.0%), heading (53.9%), panicle initiation (70.1%), tillering (72.1%), ripening (75.8%) and 5 days after transplanting (DAT) (79.0%). Protein content in brown rice was slightly larger in SMS at late growth stage than the control, while the contents of fat and ash differed very little between SMS and control. Contents of Mg and K and Mg/K in brown rice with SMS were lower at some treatment stages such as at ripening or panicle initiation.

Spikelet and vascular bundle development in rice panicles is considered to be the important elements in determining the genotype's yield capacity and translocation ability of assimilates into grains, respectively. This study was conducted to clarify the varietal differences of the spikelet and vascular bundle formations among three rice cultivars; Iksan 435 (japonica), Dongjinbyeo (japonica) and Namcheonbyeo (Tongl-type). Iksan 435 had more primary rachis branches (PRBs), secondary rachis branches (SRBs) and spikelets per panicle than Dongjinbyeo, but less than Namcheonbyeo. Among three cultivars, Namcheonbyeo showed the highest spikelet number per panicle which were differentiated SRBs mainly on PRBs of lower rachis nodes. And Namchenbyeo showed the highest number of large vascular bundle (LVB) as well as small vascular bundle (SVB) and it displayed the largest diameter of LVB. Between the two japonica cultivars, the numbers of LVBs end SVBs were significantly higher in Iksan 435 than those in Dongjinbyeo. The PRBs to LVBs ratio of Namcheonbyeo was twice as large as those of Dongjinbyeo and Iksan 435. These results indicate that the newly bred cultivar, Iksan 435, has improved yield capacity by increasing the number of especially rachis branches and spikelets formation as well as 1,000 grain weight, compared to other former japonicas

Over 2,000 ha of rice fields in the western and southern coastal region of Korea were flooded with sea water during the spring tide, on August 19-21, 1997, and the rice plant at heading stage was injured. The field surveys were undertaken at the sea water flooded paddy fields in Chonbuk Province, to identify the injury symptoms and rice yield damage subjected to different flooding condition and desalinization methods. Five days after sea water flooding at heading stage, the flag leaves of rice plants flooded with 30 ㎝ deep sea water withered from the tip, the withering progressed to the lower leaves in deeper flooding. The spikelets were spotted black and discolored from the tip at 50 ㎝ deep flooded rice, and some panicles changed to white at 80 ㎝ deep flooded rice. Most of the rice leaves submerged completely for an hour were withered and most of panicles changed to white. The milled rice yield, percentage of ripened grain, and 1000 grain weight of flooded rice decreased with deeper flooding water, higher water salinity and longer flooding time. Even under the same flooding conditions, the damage of rice yield varied with the growth stage: heading stage>dough stage>booting stage. Rice yield damage was less in the fields on the upper riverside than those of the fields on the estuary and seaside, because of lower water salinity. In a flooded field, the rice yield damages were reduced as the distance increased from the levees where the sea water inflowed and increased as the distance increased from the fresh water irrigation gate. The desalinization treatments consisting of frequent exchange of irrigation water and spraying with fresh water soon after flooding effectively reduced the rice yield damage.