Effects of nitrogen application rates on nitrogen uptake and transformation and grain protein content in malting barley

Two malting barley(Hordeum vulgare L.) cultivars,Supi 3 and Dan 2,were used to study the effects of different nitrogen application rates(0 kg / hm2,75 kg/hm2,150 kg/hm2,225 kg/hm2 and 300 kg / hm2) on accumulation and transformation of nitrogen,nitrogen use efficiency,grain protein accumulation characteristics.The results showed that Nitrogen fertilization at reasonable application rate significantly increased nitrogen content in leaves and stem and the protein content in grain at different stages.Within the range of nitrogen application rate from 0 to 225 kg / hm2 the nitrogen accumulation before anthesis and its translocation to grains were in positive responses to the increase of nitrogen rate,but there was a slight difference between the nitrogen rate treatments of 225 kg / hm2 and 300 kg / hm2.The translocation efficiency of nitrogen accumulated before anthesis and its contribution to grains showed first increases and then decreases with the increase of nitrogen rate.59.24 percent to 68.23 percent of nitrogen in grain was transferred from nutritive organs.The recommendatory nitrogen rate for malting barley should be controlled from 150 kg / hm2to 225 kg / hm2under the environments similar to that of the present experiment.