Abstract: The grainfilling characteristics of six rice varieties (combinations) and the relationships between their relative biochemistry composition during phytate synthesizing and grain plumpness were studied. Regarding results for ISHR1，ISHR2, R198 and JW21, with good grain plumpness, the twostepfilling in superior spikelets and inferior spikelets was not clear, while for ISHR3 and 559, with poor grain plumpness, it was very clear. From booting stage to flowering stage, the contents of phytate and inositol in varieties with good grain plumpness was obviously higher than those in varieties with poor grain plumpness. While at grain filling stage, the content of inorganic phosphorus in varieties with poor grain plumpness was obviously higher than that in varieties with good grain plumpness. The contents of phytate and inositol from booting stage to flowering stage was highly significantly correlated with the initial filling power (R0), the mean filling rate (RM) and grain filling percentage (PGF), and the content of inorganic phosphorus at grain filling stage was negatively significantly correlated with R0, FM and PGF. Furthermore, effective approach to improving grain filling was put forward.

Key words: grain filling, phytate, inositol, inorganic phosphorus, rice