Abstract
Two maize cultivars, Shaandan 9 (S9) and Shaandan 911 (S911), were investigated to explore the ameliorating effects of nitrogen (N) addition on their growth, water status, and N metabolism under long-term drought stress (DS). Elevated N rate increased dry matter, grain yield, relative water content, nitrate reductase activity, soluble protein concentration, and concentrations of free proline and endogenous glycinebetaine (main contributors to osmoregulation) of both cultivars under DS than control. The responses under DS were more significant for S911 than those for S9, especially at high N rate. Additionally, S9 maintained greater evaluated parameters than S911 with no N addition under DS, and these differences decreased with N application. Correlations were more evident among all parameters under DS than those under control. Thus, moderate N plays an evident physiological role in alleviation of DS effects on plant growth by improving water status and N metabolism, especially for drought-sensitive cultivars.
Acknowledgments
This work is jointly funded by the National Natural Science Foundation of China, Project No. 30571116; by the China Postdoctoral Science Foundation and Chinese Universities Scientific Fund, Project No. QN2009069; and by the Foundation of State Key Laboratory of Soil Erosion and Dryland Farming, Project No. 10501-J-2.