## 3 Results  
Seed germination began simultaneously three days after sowing, and the germination rate was 100% in control as well as in the laser-irradiated seeds of _S. marianum_. The Effect of He-Ne Laser Pre-Sowing Seed Treatment on the Vegetative Growth and Yield of S. marianum Plants  
The means of the vegetative growth parameters are presented in Table 1. The results indicated that _S. marianum_ plants from different groups of laser-irradiated seeds, except those irradiated for 8 min, produced plants with increased plant height and numbers of leaves, as well as dried weights of root and aerial parts, as compared with those plants derived from the control (non-irradiated) seeds. The plants from 8-min irradiated seeds decreased in root and aerial parts dry weight but increased in plant height and in the number of leaves as compared with the control. Plants from all irradiated seeds, except those irradiated for 2 min, had a lower number of branches as compared with the control. Interestingly, we observed that different irradiation durations resulted in selectively enhanced distinct growth parameters of the plants derived from the seeds. For example, the seeds irradiated for 4 min produced plants with the maximum plant height and root dry weight, while those irradiated for 10 min produced plants with the highest number of leaves and dried weight of aerial parts. On the other hand, plants from seeds that had been laser-irradiated for 2 min had the highest number of branches. All irradiated seeds were found to produce plants with more capitula and higher fruit dry weight as compared with the control plants (Table 2). Plants with the highest capitula number (12.0) and fruit dry weight (49.84 g) were obtained from 10-min irradiated seeds. The 6 min and 8 min treatment groups displayed the lowest fruit dry weights and capitula numbers, respectively. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \begin{tabular}{c} **Laser** \\ **Treatments** \\ **(Min)** \\ \end{tabular} & \begin{tabular}{c} **Plant Height** \\ **(cm)** \\ \end{tabular} & \begin{tabular}{c} **No. of** \\ **Leaves** \\ **(n)** \\ \end{tabular} & \begin{tabular}{c} **No. of** \\ **Branches (n)** \\ \end{tabular} & \
\begin{tabular}{c} **Root Dry** \\ **Weight (g)** \\ \end{tabular} &
\begin{tabular}{c} **Aerial Part** \\ **Dry Weight** \\ **(g)** \\ \end{tabular} \\ \hline Control & 52.3 d * & 37.0 e & 5.4 b & 3.6 c & 51.2 d \\
2 & 93.5 ab & 51.2 c & 6.8 a & 10.2 a & 89.6 b \\
4 & 96.2 a & 54.2 c & 3.6 d & 11.5 a & 61.0 c \\
6 & 91.5 b & 59.7 b & 4.7 c & 7.4 b & 66.0 c \\
8 & 62.5 c & 48.5 d & 3.5 d & 3.4 c & 44.2 e \\
10 & 95.8 a & 74.5 a & 5.5 b & 8.6 ab & 92.0 a \\ \hline \hline \end{tabular}  
* Means followed by the same letter within a column are not significantly different at the 0.05 level of probability, according to [PERSON]’s test.  
\end{table} 
Table 1: Effects of laser treatment on _Silybum marianum_ L. plant height (cm), numbers of leaves (n), numbers of branches (n), and respective dry weights of root and aerial parts (g). Effect of He-Ne Laser Pre-Sowing Seed Treatment on the Leaf Photosynthetic Pigments of S. marianum Plants  
The data in Table 3 show that all He-Ne laser treatments positively affected the chlorophyll a (Chl a), chlorophyll b (Chl b), and carotenoid contents, as all irradiated seeds produced plants with higher photosynthetic pigments as compared with the control. Consistent with the yield, the 10 min-irradiation treatment was found to produce plants with the highest Chl a, Chl b, and carotenoids contents. The enhancement trends for different photosynthetic pigments varied. The enhancement in Chl-b contents in 2, 4, 6, and 8 min were similar, while the 10 min treatment was distinctly higher as compared with the control. On the other hand, all laser treatments resulted in distinct enhancements in Chl-a and carotenoids contents. Among all of the treatments, the 8-min treatment resulted in the least enhancement as compared with other irradiation durations.