Abstract: A split root system consisting of two compartments was installed to study the effects of nitrogen form and its supply position on the growth of maize seedlings under partial root-zone water stress. Polyethylene glycol (PEG 6000) was added to the nutrient solution in one compartment to simulate partial root-zone water stress, while nitrogen was set as three forms (nitrate nitrogen, ammonium nitrogen, and their 1∶1 mixture) and supplied to just one compartment (water-stressed or non-water-stressed compartment). Photosynthetic and other physiological indices were examined.  Comparing with the nitrogen supplied to waterstressed compartment, the nitrogen supplied to non-water-stressed compartment improved the photosynthetic rate (P_n), maximum net photosynthetic rate (P_max), light saturation point (LSP), CO₂ saturation point (CSP), chlorophyll content, root activity, nitrogen uptake, and biomass accumulation, but reduced the photorespiration rate (R_p), CO₂ compensation point (CCP), abscisic acid (ABA) concentration in xylem sap, and nitrogen-and water use efficiency of the plants. Supplying nitrate nitrogen or its mixture with ammonium nitrogen improved the P_n, P_max, LSP, CSP, nitrogen uptake, and biomass accumulation, but reduced the CCP, R_p, ABA concentration in xylem sap, and nitrogen- and water use efficiency of the plants, compared with supplying ammonium nitrogen. All the results showed that supplying same nitrogen forms to non-water-stressed compartment was more beneficial to the plant growth but disadvantageous to the plant nitrogen-and water use, compared with supplying the nitrogen forms to water-stressed compartment, and supplying nitrate nitrogen or its mixture with ammonium nitrogen -promoted- the plant growth but reduced the plant nitrogen- and water use, compared with supplying ammonium nitrogen.

Key words: partial root-zone water stress, nitrogen form and its supply position, maize, seedling growth, hedgerow, ecological benefit, runoff, soil erosion, non-point source pollution.