## 3 Results and Discussion
### Distribution Uniformity
By contrast, at R1 BC DUpa dropped abruptly with spacings between 5 and 5.1 m (Figure 7). The greatest reduction of DUpa occurred in the first segments, where sprinkler spacing was greater. In this situation, with a 5.2 m spacing and corn planted at 0.52 m between rows, 10 crop lines or 20 corn plants (sowing density of 4.2 plants per linear meter) interfered with the droplet trajectory, causing great interference [36; 37]. To obtain the highest DUpa and, in turn, the smallest difference between curves that represent the phenological stages, the optimum sprinkler spacing was 2.5 m (Figure 7). The analysis of DUpa results with respect to Ids showed no significant differences for the control condition or V4, (Table 5). These DUpa values were good to excellent [19]. At V6, a significant reduction (\(p\leq 0.05\)) in DUpa was detected (between 50% and 100% with respect to 15%), whereas at V10 and R1 AC, only Id 6 mm had a significant reduction (\(p\leq 0.05\)) with respect to the remaining depths. At R1 BC, a significant reduction (\(p\leq 0.05\)) in DUpa between 100% (6 mm) and 15% (40 mm, Table 5) was recorded. These results indicate that at advanced growth stages, the highest Id performed better regarding uniformity. Thus, using 40 mm at advanced growth stages can be considered a management criterion. Distance between sprinklers and crop canopy had effects on uniformity since DUpa was significantly reduced (\(p\leq 0.05\)) from V\({}_{6}\) and at all the Ids applied (Table 5). This result is explained by the interference of plants in the droplet trajectory; indeed, this interference hinders an appropriate overlap as the distance between the canopy and the sprinkler decreases [8]. According to these authors, the magnitude of the irrigation losses depends on the storage capacity of leaves (canopy) and the amount of energy available for evapotranspiration, with losses ranging between 7% and 10%. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Irrigation Depth (Id, mm)**} \\ \cline{2-9}  & \multicolumn{2}{c}{**40**} & \multicolumn{2}{c}{**24**} & \multicolumn{2}{c}{**12**} & \multicolumn{2}{c}{**6**} \\ \cline{2-9}
* **Phenological Stage** & \multicolumn{6}{c}{**DUpa, \%**} \\ \cline{2-9}  & \multicolumn{2}{c}{**Average**} & \multicolumn{1}{c}{**CV**} & \multicolumn{1}{c}{**Average**} & \multicolumn{1}{c}{**CV**} & \multicolumn{1}{c}{**Average**} & \multicolumn{1}{c}{**CV**} \\ \hline Control & 0.90 C b & 13.3 & 0.91 C b & 15.7 & 0.85 C b & 20.1 & 0.85 C b & 11.8 \\ V\({}_{4}\) & 0.84 C a & 6.9 & 0.82 C a & 7.6 & 0.84 C a & 6 & 0.84 C a & 8.1 \\ V\({}_{6}\) & 0.84 C c & 4.5 & 0.81 C cb & 5.3 & 0.76 C ab & 7.8 & 0.76 C ab & 7.5 \\ V\({}_{10}\) & 0.70 B b & 16.3 & 0.59 B ab & 32.8 & 0.59 B ab & 27.3 & 0.45 B a & 56.6 \\ R\({}_{1}\)AC & 0.66 B b & 26.3 & 0.65 B b & 22.8 & 0.65 B b & 18.1 & 0.60 B a & 31.4 \\ R\({}_{1}\)BC & 0.51 A b & 56.8 & 0.46 A ab & 72.6 & 0.40 A ab & 87.5 & 0.32 A a & 166.4 \\ \hline \hline \end{tabular}
* * Phenological stage of corn according to [25]. Control: area of the irrigated circle with no crop; V\({}_{4}\): vegetative stage with four fully expanded leaves; V\({}_{6}\): vegetative stage with six fully expanded leaves; V\({}_{10}\): vegetative stage with ten fully expanded leaves; R\({}_{1}\)AC: reproductive stage and sprinklers above (3.20 m) the crop canopy; R\({}_{1}\)BC: reproductive stage and sprinklers below (1.60 m) the crop canopy; different uppersc letters (A, B, C) among phenological stages indicate significant differences (\(p\leq 0.005\)) according to the LSD test; significant lower case letters (a, b, c) between Ids indicate significant differences (\(p\leq 0.005\)) according to the LSD test.  
\end{table} 
Table 5: Average of distribution uniformity (DUpa) of all segments considering the different irrigation depths at each of the phenological stages and in the control condition.