Using the cultivars with high and low calcium in brown rice as tested ma- terials, the effects of calcium on photosynthetic characteristics and its subcellular dis- tribution in different rice cultivars at seedling stage were investigated with hydrocul- ture method. The results showed that the photosynthetic rate in leaves of high cal- cium cultivar was higher than that low calcium cultivar. The calcium content in leaves of rice was higher than that in roots. Among various tissues and organs, the calcium contents ranked as cell wall〉ribosome and intracellular soluble components〉 plastid （or chloroplasts）〉mitochondria〉nucleus. Cell wall is the most important distri- bution place for calcium, while calcium is rarely distributed in nuclei or mitochon- drias. In all the organelles, the calcium concentrations were all increased with the increased treatment concentration of calcium, especially in high calcium cultivar. The high calcium treatment showed more significant effects on calcium contents in im- portant organelles of high calcium cultivar, so it is speculated that the high calcium cultivar had higher calcium accumulation and tolerance capacities.
