Alternate Application of Osmotic and Nitrogen Stresses to Partial Root System: Effects on Root Growth and Nitrogen Use Efficiency

Effects of alternately applying osmotic and nitrogen (N) stresses to partial root zone were studied on maize seedlings. The maize seedlings were grown in Hoagland's nutrient solution with the roots divided equally into two containers. Half of the root system was subjected to an osmotic stress (W) using PEG 6000 added in the solution at −0.2 MPa and/or nitrogen stress (N) with the N-free Hoagland's solution. After 6 days, four of such treatments, C (control), W, N, and WN were shifted to the other halves of the root systems. Results showed that when compared to the control, total root dry weight and the root/shoot ratio increased markedly for all the stress treatments. There were no statistically significant differences in shoot biomass and N accumulation of the whole plant among all the treatments. Nitrogen use efficiency for the N and WN was significantly enhanced when compared to the C and W treatments, and the shoot N concentrations were less for N and WN than for C and W. The root vitality of...