Effect of Temperature on Starch Accumulation and Activities of Starch Synthetic Key Enzymes during Grain-filling Stage of Aromatic Rice

Changes of the content of starch, amylose and the activities of 3 key enzymes involved in starch synthetic metabolism in developing rice grains under four different temperature in phytotrons during grain filling stage of two aromatic rice varieties were studied. The results showed that compared with that under the lower temperature (21 degrees C and 23 degrees C), the content of starch and amylose and the activities of SBE and GBSS under higher temperatures (26 degrees Cand 30 degrees C) were generally higher at the beginning of the grain filling stage and obviously lower during the middle and late grain filling stage, with the exception of the activity SSS which were always higher under lower temperature. The relationship between the changes of activities of SSS, SBE and the variation of starch accumulating rate was very close and so did the relationship between GBSS activity and the amylose content. The lower activities of SSS, SBE and GBSS during the middle and late grain filling stage may be the key physiological factors which lead to the poorer progress quality and appearance quality of aromatic rice under high temperature.