The Biological Response of Different Genotypes Spring Wheat Root System to Low Nitrogen Stress

Three wheat varieties (Jiachun1,Jiachun2 and Jiachun4) were used in order to compare the genotypic variations in total N uptake, N partition between shoot and root and its relation to root morphological and physiological characters under low nitrogen stress with solution culture. The results showed that (1) Comparing with the control group, the spring wheat seedling under low nitrogen stress has small height and short root length. And numbers of root, the activity of SOD and POD of root, total root length, total absorbing area, root dry weight, and active absorbing area and root activity decreased drastically. Jiachun2 was most tolerant to low concentration of N in the genotypes; it partitioned a larger amount N to its shoot in comparison with the other varieties. The percentage of shoot N accumulation to total N accumulation was increased by7.6 % and 8.2%. The utilization efficiency of N also increased by 8.0 % and 9.9%. (2) Total N uptake was significantly and positively correlated to root dry weight, total root length, root activity, total uptake area and active uptake area under low nitrogen stress. This indicates that genotypes with large root systems are able to obtain more N from low N medium. When N is not a limiting factor for plant growth, root morphology becomes less important in N uptake.