| The increase of nitrogen application enhances nitrogen accumulation in rice plant, affects carbon/nitrogen assimilation, and thus influences starch synthesis and protein synthesis. Panicle nitrogen, which plays the most important part in nitrogen managements, influences rice growth characters, population qualities and yield, greatly. Wuxiangjing9 (japonica rice) and H97-322(indica rice) with three panicle treatments: 60kg N/ha (PNL), 120kg N/ha (PNM), and 180kg N/ha (PNH), and a control without panicle nitrogen application (PNB), were grown in Nanjing Agricultural University to study the effects of different panicle nitrogen application on the mechanism of develop physiology, rice yield, and rice quality. The results showed that:1. Panicle nitrogen application had certain inhibit effect on plant caducity; mitigated the decreases of chlorophyll content and nitrogen content of leaves; and reduced the content of MDA in flag leaves after heading. The plant caducity rates of Wuxiangjing9 and H97-322 both appeared to be PNB>PNL>PNM>PNH, and the rates decreased with the increase of panicle nitrogen amount.2. The application of panicle nitrogen fertilizer increased the bleeding intensities at the basal nodes and neck-panicle internodes at initial stage of rice grain filling. Among those different panicle nitrogen treatments, the PNM treatment distinctly affected the basal nodes and neck-panicle internodes bleeding intensities in both Wuxiangjing9 and H97-322. The application of panicle nitrogen fertilizer influenced the sucrose contents in the bleeding of basal nodes and neck-panicle internodes. In both varieties, the sucrose contents in those bleedings reached there peak levels at 14 days after heading. Among different panicle nitrogen treatments, the sucrose contents of PNM showed the highest.3. Panicle nitrogen fertilizer had complex effects on plant carbon/nitrogen assimilation. The application increased the nitrogen contents in each organs of rice plant, raised protein accumulation in rice grain, enhanced NR and GS activities; decreased the content of NSC in each organs of rice plant, mitigated the rates of starchaccumulation in rice grain. Panicle nitrogen application affected the activities of the key enzymes in starch synthesis at the middle and latter stages of grain filling, such as ADPG-PPase, SSS and especially SBE, which has distinct negative correlation with panicle nitrogen amount.4. The application of panicle nitrogen played great part in raising rice yield. With the increasing of panicle nitrogen application, the panicle per plant and spikelet per panicle increased, while the seed setting rate and 1000-grain weight decreased. The yield of PNM was the highest.5. The panicle nitrogen application strikingly affects the profile of amylograph of milled rice. The panicle nitrogen application reduced the peak viscosity, hot viscosity, and breakdown, increased final viscosity, consistency and setback, while had unmarked effect on gelatinization temperature. The application had no striking effect on the assimilations of Mg and K. But in milled rice, the Mg contents in Wuxiangjing9 and H97-322 had remarkable negative correlations with protein contents, the correlation coefficients were 0.8107 and 0.8685, respectively, while the K contents had no remarkable correlations with protein contents. The ratio of Mg to K and the product of N, AC and (K/Mg) had high correlations with eating quality, the eating quality improved with the increase of Mg/K ratio and the decrease of the product of N, AC and (K/Mg). The more panicle nitrogen applied, the lower the ratio of Mg to K, the higher the product of N, AC and (K/Mg), the worse the eating quality was.6. The application of panicle nitrogen fertilizer improves rice milling quality, and has the most important effect on the percentage of head rice among nitrogen managements. PNM treatment excellently raised the head rice percentages of Wuxiangjing9 and H97-322 for 9.73% and 21.82%, respectively. The panicle nitro...
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