Molybdenum‐induced effects on nitrogen uptake efficiency and recovery in wheat (Triticum aestivum L.) using 15N‐labeled nitrogen with different N forms and rates

Abstract

AbstractBackground: Molybdenum (Mo) is an essential microelement for higher plants and plays a significant role in nitrogen (N) metabolism, which includes nitrate reduction, assimilation, and efficient N acquisition. Its deficiency in soil may induce the reduction of N uptake and wheat yield.Aims: We aimed to explore the Mo‐induced effects on N uptake efficiency and recovery in Mo‐inefficient winter wheat cultivar using a 15N isotope tracer under different N forms (Nf) and N rates (Nr).Methods: The experiment was conducted in greenhouse conditions, and the treatments included three Nf in the form of 15NH4Cl as sole NH4+, Ca (15NO3)2 as sole NO3−, and 15NH415NO3) under two Nr [low (L) 0.05 and high (H) 0.25 g N kg–1 soil], with (+Mo) in form of [(NH4)6Mo7O24 ∙ 4H2O] and without (–Mo) Mo application. The plant biomass, Mo content, total N uptake, fertilizer 15N uptake, soil N uptake, as well as N uptake, agronomic and physiological efficiency were evaluated. Furthermore, the fertilizer 15N recovery in various wheat organs was also studied.Results: The results revealed that Mo application increased N uptake efficiency in wheat to 38.26%, 68.24%, and 71.53% when the plants are treated with low rates of NH4+, NO3−, and NH4NO3, respectively. While at a high N rate, N uptake efficiency increases to 46.26% and 45.34% in the case of NO3− and NH4NO3 treatments, respectively, and it was slightly reduced to 10.84% when plants were supplied with NH4+ form. Mo supply increased 15N recovery from fertilizer in grain organ under low N rate with all supplied Nf, that is, NH4+, NO3−, and NH4NO3, while at high N rate, Mo enhanced 15N recovery in grains organ in case of NO3− and NH4NO3 forms.Conclusion: This study shows that Mo fertilization may be a promising strategy to improve N uptake efficiency and recovery in wheat when nitrate is the main N form.