Cultivation Technology For High-yielding And High Fertilizer-nitrogen Use Efficiency In Rice

Rice (Oryza sativa L.) is the most important grain crop in China, and the application of fertilizer-nitrogen plays an important role in the increase of grain yield of rice. However, high input of nitrogen and the low nitrogen use efficiency (NUE) have become two serious problems in rice production in China. How to simultaneously increase grain yield and NUE is the hot and difficult research point. In this study, experiments were conducted in the north (Lianyungang), middle (Yangzhou), and south (Changshu) of Jiangsu Province. With the typical rice cultivars in the local as materials and the local cultivation as the contrast, effects of the super-high yielding (SHY) cultivation and the high yielding and high NUE (HYHE) cultivation on grain yield, NUE, and physiological characteristics were investigated. The HYHE cultivation was demonstrated in rice production. The main results are as follows:1. Compared with the local cultivation, the SHY cultivation and HYHE cultivation increased grain yield by 28.7% and 25.6%, respectively, and the increases were statistically significant. Increases in grain yield under SHY and HYHE cultivations were mainly attributed to the increase of total spikelets.2. The HYHE cultivation significantly increased N-uptake efficiency, agronomic N use efficiency, physiological N use efficiency and partial factor productivity of fertilizer-N, and increased N harvest index when compared with the local cultivation. The SHY cultivation increased N-uptake efficiency, but decreased agronomic N use efficiency, physiological N use efficiency, and partial factor productivity of fertilizer-N, with an exception in Changshu.3. In contrast to the local cultivation, the HYHE cultivation increased the percentage of productive tillers, biomass above and under ground, cytokinin content in roots, root oxidation activity, grain-leaf ratio, leaf photosynthetic rate in the middle and later grain-filling periods, accumulation of non-structural carbohydrate in stems and sheaths at heading, translocation of assimilates during grain filling, and harvest index at maturity.4. The HYHE cultivation was demonstrated in eight demonstration sites of new agricultural technologies in Jiangsu Province. The results showed that, when compared with the local cultivation, the HYHE cultivation reduced fertilizer-N by 5.4%, and increased grain yield by 11.6% and the partial factor productivity of fertilizer-N by 22.3%. The HYHE cultivation decreased irrigation water by 20.8% and increased irrigation water use efficiency (grain yield over irrigation water) by 48.4%.The results above suggest that grain yield and NUE could be simultaneously increased through the integration and optimization of cultivation technologies. The approaches and key techniques for high grain yield and high NUE and the evaluation indexes for NUE in rice were discussed.