Abstract
The present study was done to know the relationship between the chlorosis expression induced by cooling a certain part of the rice seedling and the starch accumulation in the leaf blade. One type of the chlorosis expression may be induced by the inhibition of chlorophyll precursor formation, which is expressed by cooling the base of leaf sheath.Another one may be caused by the destruction of chlorophyll due to the excessive starch accumulation in leaves, Experiments reported here were carried out to clarify the relationships among the chlorosis expression, the starch accumulation in the leaf blade and the sensitive parts of plant to low temperature. (1) When the rice seedling was grown under low temperature and the base of leaf sheath was cooled at 15°C, the starch accumulation was not observed in the leaf blade showed typically chlorosis. This fact implies that the chlorosis caused by the inhibition of chlorophyll precursor formation has not relations with the starch accumulation. (2) When the root of rice seedling was cooled at 15°C, the starch accumulation was clearly observed in the leaf blade and the discoloration on the top of leaf blade was recognized, but under low light intensity was not. This may imply that the discoloration of rice seedling under low temperature is induced by the cooling of root. And the stronger light intensity was given, the more sever starch accumulation was observed. (3) If the base of the leaf sheath in rice seedling is cooled at 15°C, the starch accumulation was temporally observed in the expanded leaf or the expanding leaf, but the discoloration was not observed, and then the accumulated starch diminished as time passed.
