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

Background: 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 N-15 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 (NH4Cl)-N-15 as sole NH4+, Ca ((NO3)-N-15)(2) as sole NO3-, and (NH4NO3)-N-15-N-15) under two Nr (low (L) 0.05 and high (H) 0.25-g N kg(-1) soil], with (+Mo) in form of [(NH4)(6)Mo7O24 center dot 4H(2)O] and without (-Mo) Mo application. The plant biomass, Mo content, total N uptake, fertilizer N-15 uptake, soil N uptake, as well as N uptake, agronomic and physiological efficiency were evaluated. Furthermore, the fertilizer N-15 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 N-15 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 N-15 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.

Automated summary

The study indicates that molybdenum application can enhance nitrogen uptake efficiency in wheat, especially when nitrate is the main nitrogen form. Furthermore, under low nitrogen rates, molybdenum can increase nitrogen recovery from fertilizers.