Since Japonica rice is recognized as the premium rice in some subtropical region such as Philippines, the development of new cultivar adaptable in subtropical region has been conducting. However typical Japonica rice show earlier flowering in subtropical region due to the short day length and high temperature conditions. In such a condition, it is difficult to secure enough yields. Therefore it is need that selection of Japonica cultivar showing suitable heading characters in subtropical region. Here we try to check the basic vegetative phase and heading sensitivity on temperature condition using 37 kinds of Korean cultivars. BVP is between 14 to 39 days and 37% of cultivar had basic vegetative phase between 26 to 30 days. When temperature became lower on sensitive and reproductive stage, heading was more delayed. However the 24oC condition showed the greatest impact on heading delay among temperature condition. Among cultivars, 56% of cultivars have basic vegetative phase over 25days.We checked temperature effect on heading especially sensitivity stage in those materials. Joun, Manho, Joan and Cheonga showed stable heading date under different temperature conditions. With this data, we suggest that Joun, Manho, Joan and Cheonga could be a good cultivar in subtropical region in heading characters.

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

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.

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.