Urea Use Efficiency of Hydroponically Grown Maize and Wheat

ABSTRACT

Maize and wheat were grown hydroponically with the same total nitrogen (N) level for three weeks, to evaluate the impact on plant growth and metabolism of three nitrogen sources: urea, ammonium nitrate, and ammonium sulfate. Maize growth was not strongly affected. In contrast, in wheat, growth was highest under ammonium nitrate and ammonium sulfate nutrition, and lowest with the urea solution. Ammonium nitrate and ammonium sulfate treatments favored the shoot development whereas urea enhanced the root development. Urea supply led to a higher decrease of total nitrogen content in maize as compared to wheat. Constitutive amounts of urea were found in maize and wheat whatever the nitrogen nutrition. Nitrogen uptake efficiency of plants fed with urea decreased strongly compared to nitrate or ammonium fed-plants. Results showed that when provided as sole nitrogen source, urea supply has not the same effect on metabolism and growth in maize and wheat.

Keywords:

• nitrogen fertilizers
• NUE
• NUpE
• NUtE
• urea

ACKNOWLEDGMENTS

We thank Joël TALBOTEC and François GOSSE for taking care of the plants, all the staff of the Nutrition Azotée des Plantes laboratory and the BiotechMarine society. The authors are indebted to Pr. Sylvain CHAILLOU and Dr. Christian MEYER for critically reviewing the manuscript and suggesting improvements and to Dr. Hoai-Nam TRUONG and Eugene DIATLOFF for carefully reading the manuscript.

Notes

^acontainer without plants.

∗Not detectable; nd = not determined; d = days