## 3 Results and Discussion
### Indoor Experimental Results
#### 3.1.4 Irrigation System Performance  
In both experiments, surface drip irrigation showed better performance than the subsurface drip irrigation system. The low performance results of nearly 71% on average in terms of distribution uniformity in the subsurface drip irrigation system were due to the clogging problem (Table 2). The reaction of tomato seedlings varied slightly with the two microirrigation systems. Although it is commonly perceived that surface irrigation systems such as sprinklers usually result in better tomato seedling production since the seeds are placed almost close to the surface of the soil, this common assertion cannot be taken as a general assertion. The comparison results showed that using a subsurface drip irrigation system considerably (\(p<0.05\)) impacted seedling growth. Given the concept of precision irrigation, where the input, including water, should be minimized, subsurface irrigation systems used 10% (Figure 11) less water than surface drip irrigation systems. The results of this study agreed with the work of another researcher [37]. Additionally, making the irrigation system fully automatic was also possible, but the problem could be associated with the controlling system, the time lag of sensors, unreliability in measurement [38], and  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Treatment** &
\begin{tabular}{c} **Germination** \\ **(\%)** \\ \end{tabular} & \multicolumn{2}{c}{**Root Length**} & \multicolumn{2}{c}{**Root Weight**} & \multicolumn{2}{c}{**Shoot Length**} & \multicolumn{2}{c}{**Shoot Weight**} & \multicolumn{2}{c}{**Seedling Weight**} \\  & **(\%)** & & **(cm)** & & **(g Plant \({}^{-1}\))** & & **(cm)** & & **(g Plant\({}^{-1}\))** & **(g Plant\({}^{-1}\))** \\ \hline
**Threshold** & **SD** & **SbD** & **SD** & **SbD** & **SD** & **SbD** & **SD** & **SbD** & **SD** & **SbD** & **SbD** \\ \hline
5\% & 67 b & 50 b & 4.4 & 3.2 & 1.06 c & 0.54 & 7.1 b & 14.25 & 1.27 b & 1.06 b & 1.59 & 1.31 \\
8\% & 84 ab & 67 b & 4.9 & 3.85 & 1.72 b & 2.27 & 7.2 b & 19.55 & 1.88 b & 2.93 b & 2.04 & 2.86 \\
12\% & 100 a & 100 a & 4.8 & 6 & 2.03 a & 2.07 & 10.2 b & 26.75 & 4.75 a & 8.16 a & 2.07 & 6.02 \\
15\% & 100 a & 100 a & 4.8 & 4.5 & 0.9 c & 1.2 & 17 a & 15 & 1.2 b & 2.02 b & 1.2 & 4 \\ \(p\)\({}^{*}\) & \textless{}0.001 & \textless{}0.001 & 0.983 & 0.22 & \textless{}0.001 & 0.048 & \textless{}0.001 & 0.494 & 0.004 & \textless{}0.001 & 0.27 & 0.06 \\ S.E 1 & 7.38 b & 11.78 & 1.23 & 1.34 & 0.23 & 0.82 & 1.27 & 7.97 & 0.99 & 2.57 & 0.62 & 1.91 \\ \hline \hline \end{tabular} a, b, c  Significant at \(p<0.05\), indicates significant difference between treatments. 1 Standard Error, SD: Surface drip irrigation, SbD: Subsurface drip irrigation.  
\end{table}
Table 1: Effect of surface and sub-surface drip irrigation systems and four soil moisture thresholds on germination percentage, root length, fresh root weight, shoot length, fresh shoot weight, and fresh seedling weight in the first experiment.  
the challenge of interpreting sensor data, particularly in micro irrigation systems such as drip irrigation, where the soil water distribution is heterogeneous [39]. However, there were limitations in this research to randomized small plots as the water distribution was easier to move to the adjacent plot. Additionally, the soil which was used in the experiment was not field soil with significant heterogeneity and suitable for germination. That's why 5%, 8%, 12%, and 15% moisture level was chosen to continue the experiment.