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.
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.