## 3 Results  
### Canopy Deposition on Full-Grown Carrots  
Spray configuration showed a significant effect on the relative canopy deposition [F(4, 229) = 21.831, \(p\) = 2.845 \(\times\) 10\({}^{-15}\)] in full-grown carrots, while _Air support setting_ [F(2, 231) = 2.3, \(p\) = 0.105] and _Cultivar_ [F(1, 232) = 0.003, \(p\) = 0.957] had no significant effect. Figure 4a shows the mean relative canopy deposition per spray configuration. The reference broadcast configuration XR11004 resulted in a relative canopy deposition of 45%. All bed spray configurations except XR8004, had a significantly higher relative canopy deposition than the reference. Configuration AIUB8504/AI11004 had the highest relative canopy deposition (67%), followed by XR8002 (59%), and AI8004 (56%). Configuration XR8004 had the lowest relative canopy deposition (49%), slightly higher but not statistically different from the reference broadcast application. The bed spray configurations thus resulted in (slightly) higher relative canopy depositions on full-grown carrots, although the boom height of the bed spray configurations was higher than that of the reference broadcast application (0.6 m vs. 0.5 m). Increasing the boom height generally leads to a decrease in deposition [22], because the droplets have more distance to travel before reaching the crop and are more likely to drift. The canopy depositions obtained with the different configurations are thus a result of interacting factors, including different application rates, boom heights, nozzle spacings, nozzle types, and nozzle sizes. For example, similar relative depositions were obtained with  
Figure 4: (**a**) Relative canopy deposition (%) and (**b**) relative ground losses (%) on full-grown carrots per spray configuration (mean \(\pm\) standard deviation of the mean). Different letters denote significant differences between spray configurations (Pairwise Wilcoxon test, \(p\) < 0.05). configuration AI8004 and XR8002, although at 300 kPa spray pressure these configurations produced fairly different droplet size spectra with respectively a very coarse and a medium spray (according to the BCPC spray quality class [23], as reported in [20]). Coarser droplets are generally less susceptible to air currents and are therefore more likely to collide with the plant surface as they are less likely to deviate from their initial path. By contrast, very small droplets follow almost exactly the streamlines of air flowing around an encountered object [24]. In addition, because of their higher velocity, coarse droplets are exposed to the influence of air movements for a shorter period than fine droplets [25]. Indeed, an increase in relative retention was found with droplet size spectrum on filter paper collectors [26], with highest retentions for the air inclusion nozzle compared to the flat fan nozzle. Surprisingly, _Air support setting_ did not significantly affect the relative canopy deposition in full-grown carrots. Air support is generally used to enhance transport of droplets to and into the canopy, thus improving spray penetration, deposition, and coverage, including at the underside of the leaves [27; 28; 29; 30; 31; 32]. In this trial, the air support might not have been high enough to see a significant effect on canopy deposition. The cultivation in bin may also affect the influence of the air support since the boom was relatively high compared to the ground (0.8 m bin height, 1.2-1.4 m boom height), potentially affecting the airflow behavior. Additional measurements showed that air velocities of 4.0 and 8.0 m s\({}^{-1}\) at the outlet of the air sleeve resulted in air velocities of respectively 1.2 and 2.6 m s\({}^{-1}\) at 0.5 m below the outlet, i.e., more or less at canopy height. The air velocities obtained at canopy level were therefore lower than in [33] where the air velocity at canopy surface ranged between 5 and 15 m s\({}^{-1}\).