Root morphology and nitrogen accumulation in soybean (Glycnie max L.) under different nitrogen application levels

A pot experiment was set up to study the effect of different nitrogen application levels on root morphology and nitrogen accumulation in soybean (，Glycnie max L.). The results show that nitrogen application level significantly influences soybean biomass, nitrogen accumulation and root morphology. Plant dry weight, nitrogen accumulation and per plant yield increase to the maximum point first and then decrease with increasing N application. For all the treatments, of which 100 kg(N)·hm^-2 treatment (N100) presents the best effect, the effects are in the following order: N100>N200>N50>N25>N0. Meanwhile, root to shoot ratio of soybean under N0 and N25, N50 is higher than that under N200, suggesting that low nitrogen stress enhances root development. However, root length, surface area and volume initially drop with increasing nitrogen dose, then increase and eventually decrease in the order as follows: N100>N200>N0>N50>N25. For different growth stages, plant biomass, nitrogen accumulatin and root morphology are as follows: flowering>seedling>podding. This implies that proper nitrogen application has significant effect on soybean biomass, nitrogen accumulation and root morphology. This influences transport and efficiency of nitrogen, which eventually influences the yield and quality of soybean.