## 3 Results and Discussion
### Performance Optimization  
One of the most important objectives of this study was to determine the optimum working parameters that affect qualified age seeding. For this target, the model equations obtained for in-row seed distribution uniformity were transferred to the Maple program to find the optimum values of the model equations. The roots of each model equation were found and the optimum values for all independent variables were calculated as coded values. As a result of taking the derivatives of the model equations depending on each independent variable and equating the obtained values to zero, the optimum values of the independent variables were calculated as coded values for V\({}_{\text{f}}\) and \(\lambda\), respectively. The coded optimum values obtained from the model equations were converted to real values. The optimum coded values for V\({}_{\text{f}}\) were determined to be 0.1902, \(-\)0.2109, and 0.3865 for X\({}_{1}\), X\({}_{2}\), and X\({}_{3}\), respectively. The coded optimum values obtained from the model equation were then converted to real values, and 2.114 ms\({}^{-1}\), 13.945 kg ha\({}^{-1}\), and 42.73\({}^{\circ}\) were calculated for the forward speed, seed rate, and seed falling angle, respectively. The optimum coded values for \(\lambda\) were also determined as 0.7082, \(-\)0.0569, and \(-\)0.0942 for X\({}_{1}\), X\({}_{2}\), and X\({}_{3}\), respectively. The corresponding real values were 2.425 ms\({}^{-1}\), 14.715 kg ha\({}^{-1}\), and 33.11\({}^{\circ}\), respectively. The optimum values obtained from the V\({}_{\text{f}}\) and \(\lambda\) models were found to be similar. Based on these results, if a seed rate is chosen approximately 14 kg ha\({}^{-1}\) and is set to a seed falling angle at a low degree, it could be possible to operate the seeder at a high forward speed. The sticky belt experiments were applied once again to the seed-metering unit using optimum values of 2.114 ms\({}^{-1}\), 13.945 kg ha\({}^{-1}\), and 42.73\({}^{\circ}\) which were obtained from the V\({}_{\text{f}}\) model, and also of 2.425 ms\({}^{-1}\), 14.715 kg ha\({}^{-1}\), and 33.11\({}^{\circ}\) which were obtained from optimization of the \(\lambda\) model. For these verification tests, three replications were conducted, and the in-row seed distribution uniformity performances of the seed-metering unit were assessed. The results for seed uniformity obtained from these verification tests are presented in Table 11. The highest \(\lambda\) value obtained from the experiments conducted in the CCD experimental design was 58.00% (medium) (Table 7). In contrast, the \(\lambda\) values reached 88.33% and 89% (very good) in the experiments conducted under the optimal conditions determined by the optimization of V\({}_{\text{f}}\) model and \(\lambda\) model, respectively. This indicates that the planting quality will improve under these optimal conditions, leading to an increase in the proportion of one-, two-, and three-seed strips relative to the total number of strips. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Model** & **Optimum Conditions** & \(\mu\) & \(\mathbf{V_{f}}\) & \(\lambda\) **(\%)** \\ \hline \multirow{4}{*}{V\({}_{\text{f}}\) model} & 2.114 ms\({}^{-1}\) & & & \\  & 13.945 kg ha\({}^{-1}\) & 2.24 & 0.73 & 88.33 \\  & 42.73\({}^{\circ}\) & & & \\  & 2.425 ms\({}^{-1}\) & & & \\ \(\lambda\) model & 14.715 kg ha\({}^{-1}\) & 2.23 & 0.71 & 89.00 \\  & 33.11\({}^{\circ}\) & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 11: The verification test results under optimal conditions. Similarly, in the CCD experiments given in Table 7, the V\({}_{\rm f}\) value was found to be the lowest at 1.53 (negative binomial distribution), while when working at optimum points, this value was found to be 0.73 and 0.71 in the V\({}_{\rm f}\) model and \(\lambda\) model, respectively (Table 11). These values are characterized as precision seeding (V\({}_{\rm f}\) < 0.9).