Corrected data following equation (*x* + 0.5)0.5.

ΨMeans followed by the same letters in the column do not differ by Tukey at 0.05 probability level.

**Table 7.** Inoculation with *A. brasilense* and N rates interaction in the recovery of the applied nitrogen (RAN) in wheat crop.

**Figure 6.** N rates and inoculation with *A. brasilense* interaction in the recovery of the applied nitrogen (RAN) (A) and agronomic efficiency (AE) (B) in wheat crop. Selvíria—MS, Brazil, 2015.

N applied in topdressing, the treatments inoculated provided higher values in the recovery of the applied N (**Table 7**, **Figure 6**). There was adjustment to the linear decreasing function, regardless of inoculation or not with *A. brasilense* (**Figure 6**). In the unfolding between N sources and inoculation, in the absence of inoculation with *A. brasilense*, urea provided higher RAN compared to Super N. When the N source used was Super N, inoculated treatments provided higher RAN compared to those not inoculated (**Table 8**), that is, this compensated the lower efficiency of Super N.

FE was not influenced by N rates, N sources, and inoculation with *A. brasilense* (**Table 6**), which is explained by the adequate growth of the plant (dry‐matter accumulation) even when no N was supplied due to adequate N leaf concentration in all treatments (**Table 1**), as previously mentioned.

The interaction between inoculation and rates was also significant in AE, when the rates of 50, 100, and 200 kg ha−1 of N were applied; the inoculated treatments with *A. brasilense* had higher AE compared to the non‐inoculated treatments, which is a very good result (**Table 9**) because it indicates that there were smaller losses of N with this diazotrophic bacteria inoculation. There was adjustment to the linear decreasing function of AE with and without *A. brasilense* as a function of N rates (**Figure 6**). Pankievicz et al. [38], studying FBN with ammonia release by associative fixers, verified increase and development of the *S. viridis* root system and greater CO2 fixation through inoculation with *A. brasilense* in such a way that plants cultivated in a nitrate‐limited environment similarly developed under N sufficient conditions, elucidating the ability of some mutant strains to increase BNF and positively interfering with the carbon metabolism of C4 plants, which has a close relationship with the assimilatory metabolism of N in the plant. Therefore, considering that in the experimental area, there was a favorable condition to the microbial immobilization of the applied N, and this explains why there was a higher AE of the treatments inoculated as a function of the N rates.

The interaction between N sources and inoculation in AE was significant. In treatments inoculated with *A. brasilense*, urea and Super N provided higher AE compared to uninoculated treatments. In the absence of inoculation, urea provided higher AE compared to Super N (**Table 10**). Regarding AE, according to Dobbelaere et al. [23], positive responses to inoculation with *A. brasilense* are obtained even when the crops are cultivated in soils with high levels of available

ΨMeans followed by the same lowercase letters in the column and same uppercase letters in the line do not differ by

**With Without**

The Effect of N Fertilization on Wheat under Inoculation with *Azospirillum brasilense*

http://dx.doi.org/10.5772/intechopen.68904

179

ΨMeans followed by the same lowercase letters in the column and same uppercase letters in the line do not differ by

**50 100 150 200**

**With Without**

Urea 63.36 aAΨ 50.39 aA Super N 62.86 aA 34.89 bB

**Table 8.** Inoculation with *A. brasilense* and N sources interaction in the RAN in wheat crop.

With 27.30 a 19.92 a 9.98 aΨ 9.13 a Without 17.53 b 9.22 b 6.83 a 4.44 b

ΨMeans followed by the same letters in the column do not differ by Tukey at 0.05 probability level.

**Table 9.** Inoculation with *A. brasilense* and N rates interaction in the AE in the wheat crop.

Urea 16.42 aAΨ 11.85 aB Super N 16.74 aA 7.16 bB

**Table 10.** Inoculation with *A. brasilense* and N sources interaction in the AE in wheat crop.

as a function of the production of growth‐promoting phytohormones such as cytokinin,

but mainly

N, which indicates that the plant responses do not only occur due to the fixed N2

**Sources# Inoculation**

Corrected data following equation (*x* + 0.5)0.5.

**Inoculation# N rates (kg ha−1)**

Corrected data following equation (*x* + 0.5)0.5.

**Sources# Inoculation**

Corrected data following equation (*x* + 0.5)0.5.

L.S.D. 4.31

L.S.D. (5%) 6.09

Selvíria—MS, Brazil 2015.

Selvíria—MS, Brazil 2015.

Selvíria—MS, Brazil, 2015.

Tukey at 0.05 probability level.

Tukey at 0.05 probability level.

#

#

#

L.S.D. 18.08


Selvíria—MS, Brazil 2015.
