Effects of Different Ratios of Base to Topdressing for Nitrogen Fertilizer on Rice Yield and Nitrogen Absorption and Utilization of Rice

Filed experiments were conducted to study effects of different ratios of base to top dressing for nitrogen fertilizer on grain yield and N use efficiency of Shengxiang 1 under the same soil basic fertility and nitrogen fertilizer rate.The results showed that adequate tillering fertilizer could increase yield by improving the tiller numbers of rice,while balanced fertilizer of base-tiller-panicle-granular fertilizer could increase yield by increasing number of effective panicles and grain.The fertilizer methods by improving the proportion of tillering fertilizer or panicle fertilizer,or balancing the application of base-tiller-panicle-granular fertilizer could promote N agronomic efficiency,physiological efficiency and dependency rate.But above methods had no significant effects on nitrogen partial factor productivity,and had negative effect on apparent nitrogen efficiency.There were significant differences among the amount of nitrogen accumulation in rice of each plant growing stages under different ratio of base to top dressing for nitrogen fertilizer.The peak periods of absorbing nitrogen appeared at tillering,booting or heading stage,therefore,the practice in rice production should balance base-tiller-panicle-granular fertilizer.