# Effect of Controlled Defoliant Application on Cotton Fiber Quality
## 3 Results and Discussion  
### Fiber Quality Analysis by HVI  
The defoliation timing, strategy, and leaf pubescence characteristics can impact the efficacy of defoliation and the fiber quality parameters [37; 38]. There were several studies on cotton fiber quality assessment [39; 40; 41; 42]; however, no information is available on the effects of defoliant dosage with the application of cotton defoliation with side spraying covering the whole canopy of the plant (i.e., bottom, middle, and upper). This work focused on the cotton fiber quality assessment of the newly developed sprayer prototype which can autonomously run and sprays defoliants in between the cotton rows covering whole canopy of the plant. The study indicated that defoliants dosage (20%, 40%, and 60% duty cycle) had no significant effect on cotton fiber quality in both fields (Table 4) except the Micronaire in field 2 (Table 4) which has significant result. The treatments 20% and 60% duty cycle has statistically higher micronaire value in field 2 which means that the fiber is more matured and thicker as compared to other treatments in field 2. Therefore, this showed that the defoliants could be applied safely at any of the three duty cycles without affecting these cotton fiber quality parameters. However, applying a 20% duty cycle will significantly reduce the use of chemicals; therefore, it will be a good choice for cotton defoliation. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Field\#**} & \multirow{2}{*}{**Treatment**} & \multirow{2}{*}{**Mic**} & **UHML** & **UI** & **SFI** & **Str** & **Elo** & \multirow{2}{*}{**Rd**} & \multirow{2}{*}{**+b**} & **Trash** \\  & & **(Inch)** & **(\%)** & **(\%)** & **(\%)** & **(g tex\({}^{-1}\))** & **(\%)** & & & **(Count)** \\ \hline \multirow{4}{*}{1} & 20\% & 4.19 \({}^{\text{a}}\) & 1.12 \({}^{\text{a}}\) & 82.32 \({}^{\text{a}}\) & 8.75 \({}^{\text{a}}\) & 29.92 \({}^{\text{a}}\) & 6.83 \({}^{\text{a}}\) & 83.38 \({}^{\text{a}}\) & 7.28 \({}^{\text{a}}\) & 5.25 \({}^{\text{a}}\) \\  & 40\% & 4.30 \({}^{\text{a}}\) & 1.13 \({}^{\text{a}}\) & 82.31 \({}^{\text{a}}\) & 8.93 \({}^{\text{a}}\) & 30.05 \({}^{\text{a}}\) & 6.76 \({}^{\text{a}}\) & 83.35 \({}^{\text{a}}\) & 7.11 \({}^{\text{a}}\) & 8.37 \({}^{\text{a}}\) \\  & 60\% & 4.30 \({}^{\text{a}}\) & 1.12 \({}^{\text{a}}\) & 82.06 \({}^{\text{a}}\) & 8.46 \({}^{\text{a}}\) & 30.00 \({}^{\text{a}}\) & 6.60 \({}^{\text{a}}\) & 83.16 \({}^{\text{a}}\) & 7.35 \({}^{\text{a}}\) & 5.37 \({}^{\text{a}}\) \\ \cline{2-10}  & Control & 3.96 \({}^{\text{a}}\) & 1.13 \({}^{\text{a}}\) & 81.92 \({}^{\text{a}}\) & 9.42 \({}^{\text{a}}\) & 29.95 \({}^{\text{a}}\) & 6.62 \({}^{\text{a}}\) & 84.00 \({}^{\text{a}}\) & 6.97 \({}^{\text{a}}\) & 10.75 \({}^{\text{a}}\) \\ \hline \multirow{4}{*}{2} & 20\% & 4.05 \({}^{\text{a}}\) & 1.26 \({}^{\text{a}}\) & 83.56 \({}^{\text{a}}\) & 6.75 \({}^{\text{a}}\) & 30.06 \({}^{\text{a}}\) & 8.13 \({}^{\text{a}}\) & 78.51 \({}^{\text{a}}\) & 7.60 \({}^{\text{a}}\) & 9.16 \({}^{\text{a}}\) \\  & 40\% & 3.83 \({}^{\text{ab}}\) & 1.26 \({}^{\text{a}}\) & 83.81 \({}^{\text{a}}\) & 6.50 \({}^{\text{a}}\) & 30.25 \({}^{\text{a}}\) & 8.33 \({}^{\text{a}}\) & 78.35 \({}^{\text{a}}\) & 7.43 \({}^{\text{a}}\) & 8.50 \({}^{\text{a}}\) \\ \cline{2-10}  & 60\% & 4.09 \({}^{\text{a}}\) & 1.25 \({}^{\text{a}}\) & 84.30 \({}^{\text{a}}\) & 6.75 \({}^{\text{a}}\) & 30.98 \({}^{\text{a}}\) & 8.21 \({}^{\text{a}}\) & 77.80 \({}^{\text{a}}\) & 7.55 \({}^{\text{a}}\) & 11.66 \({}^{\text{a}}\) \\ \cline{2-10}  & Control & 3.65 \({}^{\text{b}}\) & 1.23 \({}^{\text{a}}\) & 83.30 \({}^{\text{a}}\) & 7.71 \({}^{\text{a}}\) & 31.26 \({}^{\text{a}}\) & 7.76 \({}^{\text{a}}\) & 80.75 \({}^{\text{a}}\) & 7.36 \({}^{\text{a}}\) & 8.00 \({}^{\text{a}}\) \\ \hline \hline \end{tabular} Legend: Mic—Micronaire; UHML—Upper half mean lengths; Str—Strength; Elo�����{e}|longation; Rd—Reflectance; +b—Yellowness; SFI—Short fiber index; UL—Uniformity %.  
\end{table}