고온형 고분자 전해질 막 연료전지 (HT-PEMFC)는 100°C 이하의 저온 고분자전해질 운영 시스템에 비해 개선된 전극 반응 동역학, 뛰어난 물 및 열 관리, 연료 불순물에 대한 내성 및 폐열 이용과 같은 많은 이점을 제공한다. 그러나 HT-PEMFC는 구동 중 발생하는 물의 증발과 함께 분리막 내 인산이 증발하여 성능이 낮아진다는 단점이 있다. 때문에 본 연구에서는 이러한 인산의 유출에 대한 핫 프레스 유무, 전극 GDL 종류, 분리막 가수분해 조건, 셀 성능에 따른 영향을 인산의 비색정량을 통해 분석하였다. 그 결과 인산의 유출량은 주로 셀성능에 영향을 받으며 GDL이 치밀할수록 억제됨을 확인하였다.

본 연구는 UVc 처리, 열수처리와 고 CO2 처리가 저온저장으로 인해 발생하는 저온장해 현상에 미치는 영향을 비교하고, 소량으로 다른 작물과 혼합 선적할 때 유지되는 5oC 이하의 저장 유통에 적용할 수 있는지 알아 보기 위해 수행하였다. 각각의 처리 후 20일간 저온저장 후 상온에 5일간 저장하였다. 생체중은 MAP 조건이었던 고 CO2 처리구를 제외한 나머지 처리구에서 상온 저장후 급격히 감소하였으며, 에틸렌은 주기적으로 3% 내외의 수치를 보였다. 고 CO2 처리구는 저장 종료일인 25일에는 약 33%의 고 CO2 농도를 나타냈다. 저장 최 종일에 측정한 경도는 통계적 유의성은 없었으나, 저온 장해 현상이 완화되었던 열수처리에서 높았다. 저온장해 정도의 지표가 되는 전해질 용출량은 저온장해 발생온도 인 4oC에서는 고 CO2 처리구에서 가장 높았으며, 열수 처리와 UVc처리구에서 가장 낮았는데, 비저온장해 대조 구(7oC)와 유사한 수준이었다. 또한 저장최종일에 측정한 호흡률에서는 열수처리가 가장 낮아 저온장해가 완화 되었음을 알 수 있었다. 이상의 결과로 보아 저온장해 완화 효과를 보인 열수처리와 UVc 처리는 소량으로 다른 작물과 혼합 선적할 때 유지되는 5oC 이하의 저장 유통에 적용할 수 있을 것으로 판단되었다.

단옥수수와 초당옥수수 종자의 활력을 높일 수 있는 저장 방법을 알기 위하여 단옥수수(Early Sunglow × Golden Cross Bantam 70)와 초당옥수수(Xtrasweet 82 × Fortune) 종자를 온도(5 및 15℃ )와 상대습도(70 및 85%)가 다른 조건에서 10개월간 저장한 후 종자 특성의 변화를 보면 다음과 같다. 1. 종자활력은 초당옥수수가 단옥수수보다 더 빨리 저하되었으며, 초당옥수수가 단옥수수보다 더 낮은 저장온도와 상대습도가 요구되었다. 2. 단옥수수는 저장조건과 저장기간에 따른 cold test에서 출아율이 25℃ 에서 발아율보다 약간 낮았으나 경향은 같았고, 초당옥수수는 cold test에서 출아율이 25℃ 에서 발아율보다 현저히 낮았다. 3. 단옥수수와 초당옥수수 모두 발아율과 저온처리 후 출아율과는 정의 상관이 있었으나 초당옥수수는 관계가 적었다. 그래서 초당옥수수의 포장 출아율을 추정하기 위하여 반드시 저온처리 후 출아율 검정이 필요하였다. 4. 단옥수수는 모든 저장조건에서 5개월간은 종자활력이 저하되지 않았으나, 초당옥수수는 5℃ , RH 70%에서 활력이 유지되었다. 5. 단옥수수에서는 종자활력과 침종시 종자의 당 누출, 전해질 누출 및 α-amylase 활성과는 상관이 없었다. 반면 초당옥수수에서는 종자활력과 α-amylase 활성과는 정의 상관이, 침종 시 종자의 전해질 누출과는 부의 상관이 있었으나 당 누출과는 상관이 없었다

In Korea, production of super sweet corn has been economically feasible and is substituting for traditional sweet corn due to better flavor in recent years. Major limiting factors for super sweet corn production are low field emergence and low seedling vigor. The optimum water potential (WP) for the priming of normal and aged seeds of dent, sweet (su) and super sweet (sh2) corns was studied to improve low seed quality. Seeds were primed at 0, -0.3, -0.6, -0.9, and -1.2 MPa of polyethylene glycol (PEG) 8000 solution at 15~circC for 2 days. Priming effects differed depending on the type of corn, seed quality, and WP of PEG solution. Although WP of priming solution did not influence the emergence rate of extremely high quality normal dent corn seeds, it reduced time to 50~% emergence (T50) and increased plumule weight. In contrast, the emergence rate of aged field corn was improved by seed priming at 0 MPa and plumule weight and α-amylase activity was enhanced. The optimum WP for both normal and aged sweet and super sweet corn seeds was between -0.3 and -0.6 Mpa. At the optimum WP emergence rate, α-amylase activity, and content of DNA and soluble protein increased, while T50 and leakage of total sugars and electrolytes reduced.

The production of sweet (su) and super sweet corns (sh2) has been economically feasible in Korea in recent years. Major factors limiting super sweet corn production are low germination and low seedling vigor. Since seed quality is closely related to seed maturity, the optimum harvest time for the seed production of sweet and super sweet corns was studied and the quality of seeds with varying maturities was investigated in 2001 and 2002 cropping seasons. The parents of the sweet corn seeds were Hybrid Early Sunglow and 'Golden Cross Bantam 70' and those of super sweet corn were Xtrasweet 82 and 'For­tune'. Seeds were harvested at 21, 28, 35, 42, 49, and 56 days after silking (DAS). As the seeds developed, seed weight of sweet corn increased and the seed moisture content decreased faster than that of super sweet corn. Germination rates of sweet corn seeds harvested 21 and 28 DAS at 25~circC and emergence rates in the cold soil test were significantly lower than those of seeds harvested after 42 DAS in both years. Although the germination rates of super sweet corn seeds with varying maturities showed similar patterns as sweet corn seeds at 25~circC , the emergence rate of super sweet corn seeds in cold soil test continuously increased with seed maturity. This suggests that seed quality of super sweet corn should be tested in a cold soil test to estimate field emergence. As the seeds developed, leakage of total sugars and electrolytes from the both sweet and super sweet corn seeds decreased up to 42 or 49 DAS. The α-amylase activities of both sweet and super sweet corn seeds increased with seed maturity from 21 to 35 or 49 DAS depending on genotype and year. The optimum harvest time for the seed production of sweet corn was 42 DAS and 49 DAS for super sweet corn considering emergence rate and plumule dry weight in the cold soil test, leakage of sugars and electrolytes from the seeds, and α-amylase activity.

The responses of soybean seeds were evaluated to accelerated aging and gamma irradiation with regard to germination, seed leakage, seed leachate component and dry weight of hypocotyl and primary root of the germinating seed. Accelerated aging significantly reduced the final germination rate while gamma irradiation increased the final germination rate. Furthermore, the interactive effects occurred that the final germination rate of 5-day aged seeds increased considerably in response to 4 Gy of gamma irradiation. The extent to which the electrolyte was leaked from the seeds (conductivity) was significantly affected by accelerated aging and showed a close negative correlation with the germination rate. Gamma irradiation, however, did not significantly affect the electrical conductivity of seed leachate. The accelerated aging significantly increased the concentrations of the particular electrolytes leaked from the seeds while the gamma irradiation did not affect those concentrations. Of the electrolytes leaked from the seeds, Ca and Mg showed relatively lower concentrations while K showed greater concentrations than others. Moreover, N and P showed similar responses to aging treatment. Aging treatment significantly affected dry weight (DW) of hypocotyls and primary root. Also, gamma irradiation decreased DW of hypocotyls and primary root, particularly for 8 Gy associated with 5 days aging treatment. The data were discussed in terms of the relationships of seed vigor with aging treatment and gamma irradiation.

The conductivity test is a measure of electrolytes leakage from plant tissue. The shorter the maturation period after heading was the greater electrical conductivity (EC) of rice seed. The polymer-coated seed was not different in EC compared with non-coated seed. As soaking time of rice seed increased, EC increased gradually. The EC varied from 9.9 to 20.7~mu S cm-1g-l for control plots and from 21.3 to 41.7~mu S cm-1g-l for heat-killed seeds which were produced by autoclaving seeds at 121~circC for 20 minutes. The germination speed (the rate of 5th day) of rice seed was 94% at control plot, 83% at low temperature and 20% at high temperature. Besides, germination percentage was 95% for the control, 92% for the low temperature treatment and 39% for the high temperature treatment. The EC was negatively correlated (r=-0.771** ) with germination percentage at low temperature. Water uptake in seeds of 30, 40, 50 days after heading (DAH) was greater than that of 20 DAH. Plant height of seedlings was 9.84 cm for the control but 4.32 cm for the high temperature treatment, and the tallest for polymer-coated seed. Dry weight of seedlings was 0.841 g for the control and 0.287 g at high temperature. Besides, the polymer-coated seed was heavier than non-coated seed. The number of roots was largest from 40 to 50 DAH and polymer-coated seed, but was decreased from 20 to 30 DAH. The length of roots was 20.52 cm at control plot and 19.89 cm polymer-coated seed but 8.68 cm for the low temperature treatment and 7.28 cm for the high temperature treatment.