Abstract: Annual changes of boron (B) and soluble sugar (SS) concentrations were investigated in fruits and leaves of both Newhall (Citrus sinensis Osbeck) and Skaggps Bonanza (C. sinensis Osbeck) navel orange in the south part of Jiangxi province. The results showed that B concentrations in the rind were relatively high during fruitlet growth, and then those of both rind and pulp decreased, while the significant increases of B concentrations were detected in both rind and pulp from the two cultivars duringmiddle and late fruit enlargement. Meanwhile, B concentration decreased progressively and remained relatively low in old leaves from last season of Newhall, whereas was relatively high and changed little in old leaves from Skagg's Bonanza. During the middle and late stage of fruit enlargement, SS concentrations in both rind and pulp from the two cultivars accumulated significantly in accordance with B of them, meanwhile, notable decreases were presented for SS both in old leaves from the two cultivars and in sp ring-flush leaves from Skagg's Bonanza, whereas no obvious decrease was found for SS in sp ring-flush leaves of Newhall.

Key words: Citrus sinensis Osbeck, Navel orange, Boron, Sugar, Chemical elements deficieney, Boron deficiency