Biological Response of Roots in Different Spring Wheat Genotypes to Low Nitrogen Stress

Three spring wheat cultivars,Robin,Gzandin and Quantum,were used to compare the different responses of root systems in total N uptake,N partition between shoot and root,and its relationship with morphological and physiological characters of root system to low nitrogen stress with solution culture.The results showed that compared with the control group,the spring wheat seedlings under low nitrogen stress were lower in root dry weight and shorter in root length.And the root number,total absorbing area and efficient absorbing area,and root activity were decreased drastically.But the responses of different genotypes varied greatly.Under low nitrogen stress,Gzandin's root system had better morphological and physiological characters,its root weight,root length,root activity,root total absorbing area and efficient absorbing area were lower than those of other 2 cultivars,meanwhile,its nitrogen percentage of shoots to whole plant was increased by 7.6% and 8.2%,and its utilization ratio of nitrogen was also increased by 8.0% and 9.9% compared with the other two genotypes.Therefore,Gzandin was more suitable to growing under low nitrogen stress.The total nitrogen uptake was correlated linearly with dry weight,length,activity,total absorbing area and efficient absorbing area in roots under low nitrogen.On the contrary,the correlation between them was not so obvious under high nitrogen.It shows that the morphological form of roots plays a very important role in nitrogen uptake under nitrogen stress.