CRITICAL NITROGEN CURVE AND NITROGEN NUTRITION INDEX FOR SPRING MAIZE IN NORTH-EAST CHINA

Abstract

The study was conducted at three sites during 2008 and 2009 in the North-East China Plain (NECP). Field experiments consisted of five or six nitrogen (N) fertilization rates (0–350 kg N ha⁻¹). Shoot biomass and N concentration (N_c) of spring maize (Zea mays L.) were determined on six sampling dates during the growing season. Nitrogen application rate had a significant effect on aerial biomass accumulation and Nc. As expected, shoot Nc declined during the growing period. A critical N dilution curve (N_c = 36.5 W ^−0.48) was determined in China, which was a little different from those reported for maize in France and Germany. Besides, the N nutrition index (NNI) calculated from this critical N dilution curve was significantly related to relative grain yield, which can be expressed by a linear with plateau model (R² = 0.66; P < 0.001). NNI can be used as a reliable indicator of the level of N deficiency during the growing season of maize.

Keywords:

• critical nitrogen concentration (N_c)
• nitrogen nutrition index (NNI)
• spring maize
• dry matter

ACKNOWLEDGMENTS

This research was supported by National Basic Research Program of China (973 Program) (2007CB109306), National Science Foundation of China (30771256), Postdoctoral Science Foundation of China (20100470422) and International Plant Nutrition Institute.