## 3 Results and Discussion
Different letters in the same row indicate a significant difference, using the Duncan test (\(p\) < 0.05). without irrigation at sowing, combined with root architecture that makes soil-derived N more accessible. These factors likely result in greater N losses from the fertilizer during early growth stages [46]. When high quantities of N are applied at early stages (with low plant uptake capacity), N losses from the soil-plant system are enhanced, which leads to low N recovery efficiency and low yields [32]. In this sense, it is important to note that in this study, when fertilizing with half the recommended N rate with the inoculation of the BC (120 kg N ha\({}^{-1}\) + BC) significantly fewer nitrogen losses are observed (47.22%) compared to when wheat was fully fertilized (240 kg N ha\({}^{-1}\), 65.85%, Table 5 and Supplementary Table S4). Moreover, it has been reported that the application of 20 to 40% less N (as compared to the recommended dose) can cause a significant increment in NUE of the wheat crop without affecting the yield, and it can reduce N losses [46]. However, at the tillering stage and physiological maturity (Figure 3), all inoculated treatments had a higher total N (from both soil and fertilizer), compared to the uninoculated controls at the same dose. By the milk stage, inoculation of the BC with 120 kg of N ha\({}^{-1}\) also resulted in higher total N compared to the uninoculated treatment. It has been reported that PGPB have a great impact on nitrogen use by increasing nitrate (NO\({}_{3}\)\({}^{-}\)) uptake capacity, whether it is by the direct stimulation of NO\({}_{3}\)\({}^{-}\) transport systems, or as a result of stimulated lateral root development [47]. Moreover, all treatments at the three studied physiological stages (except the treatment of 240 kg N ha\({}^{-1}\), uninoculated, at the milk stage) took more nitrogen from the soil than from the fertilizer (Figure 3), which represents another indicator of the importance of diminishing N fertilizer rates and/or to improve their management, showing, that the use of sustainable agricultural practices is essential. It is important to highlight that the present investigation is not only about applying the PGPB but also about identifying the suitable conditions that would guarantee their maximum efficiency in the field. One of them is nitrogen management (the dose and fractionation of the applied N). Since there are no significant differences in some parameters due to the inoculation of BC (as the results observed in earlier works [5,19]), the main findings are that the same microorganisms depending on the dose and fractionation of N may or may not have the desired beneficial effect on wheat productivity. Although conducted over a single agricultural cycle, this study lays the foundation for future research aimed at strengthening the analysis of the observed phenomena through different lines of research. Furthermore, these findings are crucial to refining recommendations on the BC application in conjunction with proper N management, offering farmers potential savings from fertilizer inputs or increased profits from higher wheat productivity in individual crop cycles, while promoting more sustainable practices. Given that, to increase wheat productivity sustainably, two approaches are of importance: management practices (including crop rotation, cover crops, integrated pest management, N rate, N source, right moment of N fertilization, and N place of application, among others) and plant breeding (developing improved cultivars with desired traits such as tolerance to biotic and abiotic stresses, or high yield and quality, to mention a few). However, to guarantee the expression of genetic potential, most wheat breeding trials are carried out with high levels of N [48].