A Study On Nitrogen Management For The Late Stage Of Super Hybrid Rice

Peiai64s/E32 was used to study the nitrogen management for the late stage of super hybrid rice with three nitrogen levels (high-nitrogen level (N3), mid-nitrogen level (N2) and low-nitrogen level (NO) and three applying stages (flag-leaf stage (L1), penultimate leaf stage (L2), 3rd leaf from top (L3)). In this study, yield and its components, physiological characteristics, population quality, nitrogen-use efficiency and microstructure of endosperm of super hybrid rice were investigated systemically and the main results are as follows:1. The yield of super rice was enhanced by all nitrogen managements, i.e. total grains number, effective ears, and ripening percentage of grains and thousand-grain weight were enhanced. In the same applying stages, yield was enhanced and its components were improved when the level of nitrogen was increased except that the effectiveness was suppressed by the over-high nitrogen level. At the same nitrogen level, yield was enhanced most by L3, L2 secondly and L1 thirdly in contrast to CK. Considering the two factors, L3 at N2 is the best choice to improve yield among all nitrogen managements.2. The number of differentiated and survived primary and secondary branches were enhanced and their retrograded rates were reduced by all nitrogen managements. The differentiation of primary branches was promoted most by L1, and the differentiation of secondary branches was promoted most by L2. The retrogression of primary and secondary branches was suppressed while their differentiation wasn't promoted significantly by L3- N3L3 is optimum to enhance the survived number of primary and secondary branches among all nitrogen managements.3. Physiological activity of super hybrid rice was promoted and its senescence was suppressed to some degree by all nitrogen managements after heading, i.e. chlorophyll content, LAI, soluble protein content in grains and leaves were enhanced and their sliding rate were deferred, activity of SOD was promoted, soluble sugar content in grains, stem and sheath were raised, starch accumulation was accelerated. Nevertheless, the effectiveness was weakening when the level of nitrogen increased too high. L3 at N2 is the best choice among all managements.4. Total nitrogen, protein nitrogen, and non-protein nitrogen content of matured grains of super hybrid rice were raised by all nitrogen managements. Nitrogen-use efficiency and agronomic efficiency of nitrogen-use were increased when nitrogen level was increased and the time of applying postponed.5. The microstructure of endosperm was different as for the shape and arrangement of starch granules under different nitrogen managements. The effectiveness of N2 was best, N3 second, N1 third and CK worst. It changed slightly with different applying stages.