In the present study, starch, as a

In the present study, starch, as a storage carbohydrate, was sig-nificantly higher in the sheaths than in the functional leaves of bothcultivars, thereby acting as a short-term reservoir (Fig. 4). The starchcontent in the sheaths of the japonica cultivars was significantly lowerthan that of the indica cultivars at the early heading stage, although theresults were not significant at plant maturity. This result indicated thatthe indica cultivars possessed stronger photosynthetic capacity than thejaponica cultivars at the preheading stage, as well as a higher efficiencyfor photosynthate transport during grain filling. This may have con-tributed to the transport of Cd from the nutrient storage organs to thegrain in the indica cultivars. Further research on the relationship be-tween the amounts of Cd and the amounts of starch and soluble sugar inthe rice grains would be useful to investigate the cause of differences inCd accumulation between the two cultivars.