Comparative effects of ammonium and nitrate ions on growth and uptake of multiple elements of ruzigrass

Abstract

The preferable N source for tropical grasses and its effects on the nutritional status are still matters of priority investigation. This study aimed to explore the effects of N sources and N deprivation on growth and uptake of elements in a newly-released ruzigrass cultivar, BRS Integra. Plants were grown under controlled conditions in vermiculite and were supplied with nutrient solution containing either NH₄⁺, NH₄⁺+NO₃^-, NO₃^- or no N added in solution making. Plant biomass, chlorophyll content, transpiration, N status, and levels of selected elements were evaluated. NH₄⁺ improved biomass production and aboveground N contents. Other elements exhibited high (N, K and Na), medium (Mn), low (Ca, Cd, Cr, Cu, Mg, Ni and Zn) or non-detected (Al and Fe) translocation. Cd was included in the study because of its hazardous concentrations in agricultural soils in Brazil and its influence on N uptake and translocation in the genus Urochloa. All N sources increased the uptake of whole plant Cu and K and Al, and root Fe and Mg. Other favorable relations prevailed in the roots, specifically of NO₃^- on Ca and Ni, NH₄⁺ and NH₄⁺+NO₃^- on Cr, and NH₄⁺ on Cd. Removal of N supply caused increases on Mn and Na aboveground and Zn in roots. Overall, the more evident N source-induced uptakes were, in order of decrease, of NO₃^- on Ca, NH₄⁺+NO₃^- on Ni, and NH₄⁺ on Cr, Cu and Mn. It is concluded that NH₄⁺ is more efficient for fertilizing ruzigrass by improving growth and N uptake compared to NH₄⁺+NO₃^- or NO₃^-. In addition, the diverse effects of varying N sources on the uptake of 12 elements indicate such interactions should be taken into account to further improve fertilizer formulations.

Keywords:

• Ammonium
• cv. BRS Integra
• ionic relations
• nitrate
• nitrogen

Acknowledgements

Authors thank Sebastião de Castro Evaristo for the kind help. Paola Ramos Coutinho Reis is recipient of a doctorate fellowship from CAPES (Coordination for the Improvement of Higher Education Personnel)—Brasil. Lorena Costa Rosa de Souza Lima is recipient of a scholarship from Embrapa.

Authors’ contribution statement

Leônidas Passos: All steps of the study from conception, design and data analyses to manuscript drafting and approval of the final version. Paola Reis: Conducting the experiment, sample collection and analyses and approval of the final version. Lorena Lima: Conducting the experiment, sample collection and analyses and approval of the final version. Fausto Souza Sobrinho: Supply of plant materials, critical revision of the manuscript and approval of the final version. Júlio Silva: Analyzing and interpretation of data, literature review, critical review of the manuscript and approval of the final version.

Disclosure statement

The authors report there are no competing interests to declare.