Effects of nitrogen application rate on dry matter redistribution, grain yield, nitrogen use efficiency and photosynthesis in malting barley

The harmonious combination of malting barley yield, quality and nitrogen (N) use efficiency under nitrogen (N) rates applications was greatly conducive to production in China. The malting barley cultivar Supi 3 was planted during the growing seasons 2005 and 2006 at two contrasting sites in China. Five nitrogen (N) application rates (0, 75, 150, 225 and 300 kg ha−1) were applied for research of effects of N rates application on grain yield, protein content and N use efficiency. At both sites and in both years, grain yield increased with increasing N application rates up to 225 kg N ha−1, and decreased with 300 kg N ha−1. Net photosynthetic rate (P N) and the amount of accumulated dry matter distributed into grains showed the same response to N application as grain yield. Grain protein content increased with increasing N application rates. Moreover, based on further analysis of these results with a quadrant model, the optimum N application rates for high grain yield with high nitrogen use efficiency in malting barley could be indicated. So, the higher yields could be mainly ascribed to the higher accumulation of photoassimilates between anthesis and maturity. In order to achieve high grain yield and quality of malting barley in China farmers are recommended to fertilize with 150–209 kg N ha−1.