Abstract: 【Objective】Water and nitrogen (N) resupplies can significantly enhance root absorbing capacity. Partial water and N supplies can stimulate the compensation effect of root absorbing capacity at the non-stressed sub-root zone. The objective of this study is to identify the dynamics and influencing factors of the compensation effect of maize roots (Zea mays L. hybrid cv. Aoyu No. 3007) N absorbing capacity under partial resupply after previous water and N stresses.【Method】With the split-root technology, a hydroponic experiment was conducted to analyze the root zone water and N stresses, where the water stress was stimulated by the osmotic potential of a nutrient solution (PEG 6000) and N stress was stimulated by different N levels. There were three water and N stress levels, i.e., mild, moderate, severe water and N stresses and a control treatment (CK, both sides of the root zone supplied with sufficient water and N). The root N inflow rate, N content and accumulation of each root zone were measured at 0, 1, 3, 5, 7 and 9 d of resupplying water and N in half of root-zone 6 d after water and N stresses.【Result】Compared with non-stressed sub-root, the root N inflow rate, N content and accumulation in stressed sub-root were significantly decreased under partial resupply after water and N stresses. During 1-3 days after treatment (DAT), the root N inflow rate in stressed sub-root reduced by 38.2% and 48.7%, respectively, and was 84.9% and 86.4% lower than that in non-stressed sub-root. For non-stressed sub-root, partial water and N resupplies significantly enhanced the root N inflow rate compared with previous water and N stresses during 0-1 DAT. When water and N stresses did not exceed moderate stress level, partial water and N resupplies significantly increased root N inflow rate compared with control treatment during 0-1 and 7-9 DAT. However, during 3-7 DAT, the root N inflow rate was similar to or lowers than control treatment. The root N content and accumulation in mild and moderate stress treatments returned to control level at 1 and 5 DAT, respectively, which resulted in similar plant N use efficiency to control treatment. Moreover, partial water and N resupplies significantly increased the percentage of ¹⁵N-fertilizer-N allocation in shoot compared with control treatment, and the increment reduced with the severity of water and N stresses. For non-stressed sub-root, the percentage of ¹⁵N-fertilizer-N allocation showed a reverse trend. For mild stress treatment, the percentage of ¹⁵N-fertilizer-N allocation of stressed sub-root had no significant difference compared with that of control treatment. The percentage of ¹⁵N-fertilizer-N allocation of stressed sub-root at moderate and severe stress treatments was significantly higher than that of control treatment, at 3-9 DAT, although there was no significant difference between moderate and severe stress treatments.【Conclusion】When previous water and N stresses did not exceed moderate stress level, the compensation effect of root N absorbing capacity in the non-stressed sub-root can be effectively stimulated by partial water and N resupplies. The compensation effect was affected by the severity and duration of the water and N stresses. Percentage of ¹⁵N-fertilizer-N allocation in different organs is closely related to the severity and duration of the water an N stresses. Thus, the above conclusion provides theoretical supports for regulating the interaction between plants and soil environment and making use of the potential plant response to soil water and nutrient stresses.

Key words:  partial water and nitrogen resupplies, stress severity, duration of partial resupply, root N inflow rate, root compensatory effect, maize