Changes in Biological Nitrogen Fixation and Natural-Abundance N Isotopes of Sugarcane Under Molybdenum Fertilization
2019
dos Santos, Renato Lemos | Freire, Fernando José | de Oliveira, Emídio Cantídio Almeida | Trivelin, Paulo Cesar Ocheuze | dos Santos Freire, Maria Betânia Galvão | da Costa Bezerra, Patrícia | de Oliveira, Ruthanna Izabelle | da Costa Santos, Monalisa Barbosa
Molybdenum (Mo) can stimulate nitrogenase activity (NTA), increase biological nitrogen (N) fixation (BNF) and reduce natural-abundance N isotopes (δ¹⁵N). Our hypothesis is that this stimulus depends on genotype and N availability for sugarcane. The objective of this study was to evaluate the effect of the Mo fertilization on BNF, NTA, δ¹⁵N and the accumulation of N in different genotypes (RB867515 and RB92579) of sugarcane fertilized with N. The cultivars were subjected to two rates of N fertilization (without N fertilization and 60 kg ha⁻¹) and two rates of Mo fertilization (without Mo fertilization and 200 g ha⁻¹). NTA, δ¹⁵N and BNF were evaluated throughout the cycle of the sugarcane. Both leaf and root NTA was maximal at approximately 100 DAP. Mo fertilization stimulated NTA in RB867515 but reduced in RB92579. The bacteria associated with the sugarcane fixed atmospheric-N₂ and the Mo fertilization stimulated this fixation, especially without N fertilization. Mo fertilization promoted greater N accumulation and should be encouraged for fertility management, especially in soils with low N content or as an alternative for reducing the use of N fertilizers in sugarcane.
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