Effects of nitrogen application on the leaf of C/N and nitrogen uptake and utilization at later developmental stages in different high yield hybrid rice varieties

The effects of nitrogen application on the characters of uptake nitrogen and leaf of C/N and nitrogen use efficiency of different high yield hybrid rice varieties were studies under field conditions.The results showed that N uptake amount different were existed at different rice varieties during the period from heading to ripening and the N uptake amount occupied above 70 % at before heading.Wandao125 had stronger uptake nitrogen capacity at condition of lower nitrogen and proper nitrogen,which promoted accumulation of dry matter and yield production.Variation coefficient of the content of leaf carbon between different varieties was lower.C/N of leaf was higher.C/N at the heading,kernel-filling and maturing stages were 28.6%、18.3%、36.4% higher respectively under CK plots than N-application plots.The proper C/N may promote the nitrogen translocation and yield production.Agronomic efficiency and physiological efficiency under proper using nitrogen of Wandao125 were 13.97 kg/kg and 56.5 kg/kg respectively.It was highest in tested cultivars and higher 10.2% and 24.4% than Shanyou63.