| Some combinations of inter-subspecies hybrid rice which are spread widely at present have some superiorities in larger spike, more grains and stronger growth potential, but their low grain filling degree is a major restricting factor for their application and extension. High performance liquid chromatographic determination of endogenous hormones , correlation between grain filling parameters and grain filling degree of inter- subspecies hybrid rice, the mechanism and chemical regulation of grain filling were studied in this dissertation, using inter-subspecies hybrid rice combinations with different grain degree, intervarietal crossing rice and conventional rice as materials, the results showed that:1. Determination method of endogenous phytohormones in inter-subspecies hybrid rice has been established. It makes PVP and DEAE columns with variant properties connect to purify samples and utilizes Cjg Sep-Pak columns to gather selectively endogenous hormones, washes with different solution at variant time instead of extracting and transferring repeatedly, So the method avoids classical ways' shortcomings, at the same time its extraction rate is higher, thus the sample is isolated very good (contrasting the classical ways ). And linear relationship (correlationcoefficient, linear range and detection limit), recovery rate and repeatability of this method were also analyzed and results of test coincides with quantitative requirements.2. The poor grain filling of inter-subspecies hybrid rice is a common phenomenon but there are really some good exceptions of grain filling combinations. For example, ISHR1 has a good grain filling degree, while its grain filling parameters are significantly different from other combinations with poor grain filling degrees. Initial growth potential, maximum grain filling rate, and mean grain filling rate of inter-subspecies combinations have little diversity between superior grains and inferior ones. Grain filling rate of superior and inferior grains appear to be synchronous in good grain filling combinations but antipodal in poor grain filling combinations. These results show that the main causes of poor grain filling are later filling initiation and lower filling rate of inferior grains. The situation was found to be similar hi conventional varieties of different filling degrees.This dissertation also indicated that the major restricting factor of grain filling is not the supply of assimilates, but physiological activities of sink.3. The endogenous hormonal concentrations and the activities of some enzymes of grain can reflect physiological activity of grain to a certain degree. The regular variations of endogenous indole-3-acetic acid(IAA), zeatin(Z), gibberellic acid(GA3) and abscisic acid(ABA) concentrations of grain were closely related to grain filling during grain development . Correlation analysis indicated that the IAA and Z concentrations of grain at booting stage to blooming stage were significantly or very significantly correlated with initial grain filling potential (Ro), mean gram filling rate (Fmean) and grain filling percentage (GFP); the IAA, Z and ABA concentration of grains at blooming stage to 15 days after flowering were significantly correlated with RO, Fmcan and GFP; the IAA and Z concentration of grams 15 days after flowering were significantly and negatively correlated with RO?Fmcan and GFP. Thecorrelations between GA3 concentration and RO?Fnwan' GFP were not significant. These results suggested that it could be key measure for enhancing grain filling and increasing grain filling percentage of inter-subspecies hybrid rice by raising the IAA and Z concentration from booting stage to 15 days after flowering especially from booting stage to blooming stage.The phytate and inositol concentration in grain were very significantly correlated with RO?Fmean and GFP, and the phosphorus concentration of grains was significantly correlated with RO, Fmcan and GFP from booting stage to blooming stage. The phytate concentration of grains was very signi...
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