Nitrification inhibitor application at stem elongation stage increases soil nitrogen availability and wheat nitrogen use efficiency under drought stress

ABSTRACT

One of the practices which could mitigate the negative effects of drought stress is ammonium nutrition. Nitrification inhibitor (DMPP) can keep ammonium concentrations high in the soil for several weeks. Although there are contradictory reports regarding the priority of NH₄⁺ uptake and its toxicity effects on wheat, it is necessary to understand better how to apply DMPP to increase drought tolerance without any negative effects. The field experiment was conducted using ¹⁵N trace technology. The fertilizers treatment included (¹⁵NH₄)₂SO₄ and (¹⁵NH₄)₂SO₄ with DMPP at four drought stress levels. Available soil mineral nitrogen was measured, as well as yield components and ¹⁵N recovery. The results showed that DMPP application at full irrigation and moderate drought stress caused an increase in grain yield of 13% and 10%, respectively. DMPP application at full irrigation, moderate and severe drought stress caused a significant increase in nitrogen use efficiency of 19%, 11%, and 17%, respectively. It seems DMPP application at the stem elongation stage, promoted NH₄⁺ assimilation and transfer to the shoots, which has created relative resistance to drought stress conditions. In conclusion, it is recommended that farmers use DMPP at stem elongation to avoid wheat yield reduction and nitrogen recovery under drought stress.

KEYWORDS:

• Ammonium
• DMPP
• nitrate
• stable isotope
• ¹⁵N labeling

Acknowledgements

The authors are grateful to the Nuclear Science and Technology Research Institute (NSTRI) for providing research support, laboratory equipment, and all the necessary facilities to carry out the project. Furthermore, we offer a special thanks to the field and laboratory assistants and technicians working with us at the Soil and Water Research Department and the field station of Zafaraniyeh (Nazanin Pourmohammad, Rahman Rahmati, Seyedomid Najafabadi, and Fatemeh Ajili) as well as Emission Spectrometry NOI7C laboratory staff for the measurements of ¹⁵N.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.