This study was conducted to clarify the effect of high temperature during winter period(autumn sowing) and spring sowing on yield, quality and growth and development in barley. The varieties used for the experiments were heenchalssalbori and keunalbori 1 having a strong spring habit characteristics. In spring sowing treatment, spikelet differentiation was proceeded rapidly and tillering was proceeded slowly compared to the development stage, because the barley sowed at spring is cultivated in high temperature and long day conditions from sowing to spikelet differentiation stage compared with autumn sowing(control). And in high temperature treatment during winter period, like spring sowing, tillering was inhibited compared to the development stage. The number of grain per panicle and the period required to heading stage from spikelet differentiation were reduced largely at spring sowing, because spring sowing treatment was conducted in high temperature and long day condition compared with autumn sowing and high temperature treatment during the period from spikelet differentiation to heading stage. Meanwhile in spring sowing treatment, average temperature during ripening stage was higher than the autumn sowing and high temperature during winter, because heading stage was so late. After all, starch, amylose content and grain weight were reduced while protein content was relatively increased in spring sowing treatment due to difference of average temperature of ripening stage. These changes affected the decrease of viscosity of peak, trough, breakdown and the increase of setback viscosity

We investigated the changes in the physicochemical properties of wheat grains during ripening stage to determine the effect of the rise in average temperature on that of wheat grains. The treated average temperatures were 18.3°C(control), 19.9°C(1.6°C increase), 21.5°C(3.2°C increase) in artificial climate room from heading time to harvest. Results showed that the ripening period from heading to maturity tended to be shorter during higher temperature treatment condition. The 1,000-grain weight, grain width, number of florets per spike, and number of grains per spike decreased as the ripening period was shortened. Gelatinization properties were affected by high temperature due to the reduction of starch and amylose contents. As the grain filling period was shortened by high temperature treatments, the crude protein content increased. As the grain filling period was shortened by 6 days, the starch and amylose contents decreased by 10.8% and 5.4%, respectively. However, the crude protein content increased by 1.7% in such a condition. Starch content showed positive correlations between amylose and breakdown. Meanwhile, it showed negative correlations between electric conductivity of leaching water from seeds, crude protein content, peak viscosity, trough viscosity, final viscosity, and setback.

We investigate the change of leaf chlorophyll content according to iron content in brown rice when cultivated on the iron limited solid MS medium. By cultivating wild-type and transgenic brown rice in a solid MS medium, we confirmed that iron deficiency chlorosis did not occur in MS media which were contained over 20% of iron content compared to normal MS condition. After selecting twenty kinds of Korean rice varieties, those brown rice were cultivated in solid MS media which were contained from 0 to 15% of iron content compared to normal MS condition then the leaf chlorophyll content was measured. The leaf chlorophyll content was changed according to iron content in brown rice when cultivated in solid MS medium which was contained 0 and 5% of iron content,. There was a strong correlation between iron content in brown rice and leaf chlorophyll content cultivated in solid MS medium with 5% of Fe content. Therefore we expect that analysis of leaf chlorophyll content after cultivated on MS medium with 5% iron content compared to normal MS media condition will be more simple and effective method to screening high iron content brown rice without measurement of iron content.

This experiment was conducted to clarify the effect of the high temperature on physicochemical properties of barley kernels during ripening stage. High temperature treatment was lasted from each 10, 17 and 24 days after heading(DAH) until the harvest time at 21oC, 24oC, 27oC in artificial climate room. The results showed that ripening period from heading to maturity was tend to be shorter at higher temperature treatment condition and at longer duration treatment condition. and 1000-grain weight was decreased as the ripening period shortened. Furthermore, gelatinization properties was changed by high temperature due to the reduction of starch and amylose contents. As the shortening of grain filling period by a high temperature treatment, the protein content was increased. In the 10 DAH at 27oC treatment, the grain filling period was shortened by 9 days. The starch contents was reduced by 5.7 %, and the protein content was increased by 5.6 % in a such condition. Protein contents was showed negative correlations with amylose, starch contents and gelatinization properties, respectively. Starch contents, however, showed positive correlations with amlyose content and gelatinization properties.

Limonium tetragonum is a halophyte grown naturally in the coastal region in South Korea. This study was conducted to investigate the effects of salt concentrations on seed germination, seedling growth, and antioxidant capacity of L. tetragonum. Seeds were collected from naturally grown plants of L. tetragonum and those at full maturity were used in this experiment. All experiments were performed at 0%, 0.5%, 1.0%, or 2.0% of salt concentrations. Seed germination rate was highest as 86% at 20℃ and followed as higher in order of 25℃, 30℃ and 15℃. The germination rate was about 80% at 0% or 0.5% of salt concentration, but it was very low at the salt concentrations higher than 1%. Growth of L. tetragonum seedlings showed no difference in Hoagland solution containing NaCl in the range of 0% to 1.0% and seedlings survived at 2.0% of NaCl concentration. As the salt concentration increased, the content of Na+ in the shoot increased, but that of K+, Ca++, or Mg++ decreased. The antioxidant activity and the content of total polyphenol and total flavonoid in the shoot were similar at 0% and 0.5% of NaCl and were highest at 2.0% of NaCl concentration. In conclusion, performance of seed germination and plant growth of L. tetragonum was highest at 0% and 0.5% of NaCl concentration, and showed no difference in antioxidant activity, total polyphenol contents, and total flavonoid contents at the same salt concentrations.

This experiment was conducted to evaluate the effects of high temperature on the stem, leaf and grain of barley during the ripening period and to provide information for the development of high-temperature cultivation techniques and adaptive varieties. We used an artificial climate control facility, to provide a temperature 3℃ higher than the normal average temperature during the ripening stage. Although the maximum rate of starch synthesis was increased at high temperature by approximately 11%, the starch content was decreased, because the period of starch synthesis ended 4 days earlier. As in the case of starch synthesis, the expression of genes related to starch synthesis was increased at the early ripening stage in the high temperature treatment, however, the duration of expression tended to decrease rapidly. Furthermore, the partitioning rate of assimilation products in the panicle increased to a greater extent in the high temperature treatment than in the control. In contrast, for the stem and leaf, the partitioning rate of assimilation products decreased more rapidly in the high temperature treatment than in the control. On the basis of these results, it can be considered that the translocation rate of assimilation products increased to a greater extent in the high temperature treatment than in the control at the early ripening stage. These results indicate that the decrease in grain weight at high temperature during the ripening stage is attributable to an increase in the speed of starch synthesis at high temperature, but the increase in ripening speed does not compensate for the shortening of the ripening period. Finally to develop varieties and cultivation techniques suited to high temperature, we need to focus on physiological characteristics related to the duration of starch synthesis.

The increase in the frequency of occurrence of abnormal weather could include severe rainfall, which could cause rice submergence during the ripening stage. This experiment was conducted to clarify the effects of submergence during the ripening period on yield and quality of rice. The flooding treatment was conducted at 7 and 14 days after heading. Flooding conditions were created with two conditions, flag leaf exposed and overhead flooding, and each condition was divided into two conditions according to water quality—clear and muddy. Although the yield decrease was more severe at 7 days after heading because of the decrease in the ripening ratio, the head rice ratio was more affected at 14 days after heading because of the increase in the chalky kernel ratio. The maximum quantum yield (Fv/Fm), which indicates the photosynthetic efficiency, did not differ before and after the flooding treatment until flooding continued for 4 days. In addition, stem elongation occurred because of flooding as an avoidance mechanism in japonica rice. This phenomenon was expected to decrease the supply of assimilation products to the spikelet (sink). Overall, it was suggested that additional experiments should be conducted examining the change in the starch synthesis mechanism and transfer of assimilate products resulting from submergence, for development of cultivation techniques corresponding to submergence and breeding of varieties with submergence tolerance characteristics.

간척지에서 재배될 수 있는 염생식물은 국토의 효율적 이용과 식량의 안정적인 확보 측면에서 매우 중요한 유전자원이다. 본 연구에서는 염생식물인 퉁퉁마디의 작물로서의 이용을 위하여 종자의 발아특성과 염농도에 따른 생육특성을 규명하고자 하였다. 퉁퉁마디 종자는 화피로 둘러싸여 있는 난형으로 연한 갈색을 띄었으며, 수분흡수 후 종피가 파열되면서 유근이 출현하여 발아가 시작되었다. 퉁퉁마디 종자의 발아에서 화피의 영향을 알아보기 위하여 최적 발아온도로 알려진 25℃와 30℃에서 raw seed와 화피제거 종자의 발아율을 조사하였다. Raw seed는 25℃에서 5%, 30℃에서 7%의 발아율을 보인 반면, 화피 제거 종자는 25℃에서 53%, 30℃에서 58%의 발아율을 보여 화피 제거에 의하여 종자의 발아율이 급격히 상승하였다. 따라서 종자의 발아율을 높이기 위하여 500㎛ sieve를 이용하여 화피를 제거할 수 있는 기계적 방법을 개발하였으며 이 방법에 의하여 화피가 제거된 종자를 90% 이상 확보할 수 있었다. 화피 제거 종자의 염농도에 따른 종자의 발아율을 조사한 결과, 0mM에서 53%, 50mM에서 49%, 100mM에서 35% 그리고 200mM에서는 26%로 염농도가 낮을수록 발아율이 높은 것으로 나타났다. 한편, 유묘의 염농도에 따른 생장량 조사를 위하여, 2주된 유묘를 상토에 이식하고 0~200mM의 염처리를 하여 5주간 초장과 분지수를 조사한 결과, 퉁퉁마디의 생장량은 100mM에서 가장 많았다. 따라서 퉁퉁마디의 유묘확보율을 높이기 위해서는 종자의 화피를 제거하여 염농도 0mM인 25~30℃에서 발아를 시키고, 유묘생장단계에서는 100mM 전후의 염농도가 최적조건으로 판단되었다.

새만금 간척지를 포함하여 우리나라는 넓은 간척지를 보유하고 있으나 제염되지 않은 간척지에서 재배할 수 있는 농작물은 매우 한정적이다. 따라서 높은 염농도에서도 재배 가능한 염생식물인 나문재의 작물로서의 이용을 위하여 본 연구에서는 나문재의 종자구조와 염농도에 따른 유묘생육 특성을 조사하였다. 나문재는 쌍떡잎 식물로서 종자 내에 배유층이 존재하지 않으며, 종자를 화피가 감싸고 있고 결실기에 화피가 바깥쪽으로 신장되어 오각형의 별모양의 형태를 보였다. 종자 크기는 길이가 0.44±0.10cm, 너비가 0.47±0.09cm, 폭이 0.31±0.06cm이었으며 천립중은 1.58±0.07g이었다. 화피를 제거하면 길이 0.31±0.05cm, 너비 0.31±0.06cm, 폭은 0.12±0.04cm였으며 천립중은 0.74±0.06g이었다. 종피가 감싸고 있는 종자의 내부는 shoot apex를 중심으로 배축이 나선형으로 두 번 반정 감겨져서 종자 바깥쪽으로 radicle이 향하고 있는 구조를 가지고 있다. 종자 침종 후 발아하는 데는 30℃에서 평균 3일 정도가 소요되었으며, 발아 시 radicle이 종피를 뚫고 신장하였으며, 이 때 나선형의 배축이 풀리고 황색의 떡잎은 짙은 초록색으로 변하면서 갈라져 신장하였다. 염조건에 따른 유묘의 생장 특성을 조사하기 위하여 초장 10cm 내외의 유묘를 상토에 이식하고 염농도를 0, 20, 50, 100, 200mM로 처리하고 5주 간 생육조사를 실시하였다. 그 결과, 나문재의 초기 생장량은 염농도 50mM에서 초장이 55.95±6.30cm, 분지가 56개로 가장 많았으며, 100mM에서는 50mM의 생장량보다 약간 적었으나 유의한 차이를 보이지는 않았다. 반면, 생육이 가장 부진하였던 200mM에서는 50mM에 비하여 초장은 19.05cm, 분지는 13개 감소하였다. 이와 같은 결과로 볼 때, 나문재는 적정 생육 염농도는 50~100mM 정도로 판단되었다.

본 연구는 벼의 출수 후 일수에 따라 수발아 양상을 조사하고 수발아 피해가 발생할 수 있는 시기를 예측하여 수발아 방제를 위한 기초자료를 얻고자 수행하였으며, 그 결과를 요약하면 다음과 같다. 1. 벼 등숙기간 중 호품벼는 출수 후 20일, 신동진벼는 출수 후 30일부터 수발아 조건이 충족되면 발아가 시작되었으며, 50% 이상의 종자가 발아력을 갖는 시기는 호품벼가 약 35일, 신동진벼가 약 45일이었고, 출수 후 50일에는 두 품종에서 모두 80% 이상의 종자가 발아하였다. 2. 한 이삭 내에서 종자의 위치에 따른 수발아의 순서는 상위부 > 중위부 > 하위부 순으로 나타났으며 지경별로는 2차 지경보다는 1차 지경의 것이 높게 나타났다. 3. 수발아 검정 시 미발아된 종자는 배의 미숙, 종자휴면, 종자의 등숙불량 (불완전립)이 원인인 것으로 판단되었다. 4. 출수 후 30~45일의 등숙중기에 신동진벼는 호품벼보다 종자 휴면성이 높았다.