## 3 Results and Discussion
The highest value of stimulation in the height of the plants was obtained at t = 20 s, with significantly increased growth (stem diameter, root length, and height of plants) for the exposure times of 5, 10, and 20 s [45]. The exposure of maize seeds for 85 s with 2 mW/cm\({}^{2}\) power density of blue laser increased the weight of 300 seed (55.3 g); however, compared to the control (52.7 g), there was no significant difference (Table 2). The yield of maize seed (t/ha), as shown in Table 3, exhibited significant differences. In general, using different wavelengths with different exposure times led to an increase in the seed yield. For the blue laser, 85 s of exposure in 4 mW/cm\({}^{2}\) had higher yield (7003.4 kg/ha), followed by seeds irradiated with power density 2 mW/cm\({}^{2}\) (6939.9 kg/ha), which significantly increased yield compared to control (6259.5 kg/ha). However, the application of different lasers at both powers with different exposure times significantly increased the yield efficiency (g/cm\({}^{2}\)) for maize seeds (Table 2). As a general trend, increasing exposure time using the green laser led to a remarkable increase in yield efficiency. The maximum yield efficiency (17.5 g/cm\({}^{2}\)) of different types of lasers was obtained with exposure (85 s) to the green laser for 2 mW/cm\({}^{2}\) followed by 16.9 g/cm\({}^{2}\) exposure to the He-Ne laser in seeds irradiated for 105 s combined with power 4 mW/cm\({}^{2}\). The control (unexposed) group resulted in yield efficiency of 14.5 g/cm\({}^{2}\). The values of the harvest index (%) of maize, as shown in Table 2, showed that all different laser types and the various exposure times resulted in a marked increase in the harvest index, but no significant effect was observed according to statistical analysis. The highest value, 23.6%, was obtained from the third exposure time (85 s) of the blue laser at 4 mW/cm\({}^{2}\), as compared to the control group, which exhibited the lowest harvest index percentage (20.7%). The irradiation of the maize seeds by various lasers and exposure times had a significant influence on the harvesting index and yield efficiency. Hence, in the case of the seeds irradiated by the blue laser, an increase in yield was due to a change in other growth and yield-generating features. Furthermore, [PERSON] et al. [22] found that laser bio-stimulation of tomatoes increased the number of flowers, fruits, bunches, polar mean diameter, equatorial mean diameter, weight of the fruits, and yield per plant. However, [PERSON] et al. [41] indicated a positive bio-stimulation in bean seeds, which were irradiated by blue laser and obtained an enhancement of 47% in germination as compared to the control sample. [PERSON] and [PERSON] [21] found that laser irradiation accelerates the growth and biomass of willow varieties (_Salix_ sp.). Similarly, the effects of the spectral impact of the laser on seed performance were reported [27]; laser irradiation induces a change in the plant development and makes the cell divide faster, which results in faster initial rate of growth and improvement. Therefore, the significant effect of laser light on growth and yield parameters in the present study could have been due to an increase in cell division. [PERSON] et al. [9] found that irradiating wheat seeds with laser in dry and humid conditions produced greater yield, as compared to non-irradiated seeds (control). The best efficiency was obtained with the 532-nm laser at two regimes of irradiation, with the effects of bio-stimulation being more evident at a higher salt concentration [46]. Irradiation with laser could be an alternative to control diseases in maize seeds (_Zea mays_ L.) and, in this way, could improve the sanitary quality of the seed and possibly of the final product obtained from the plants with seeds treated with a laser. Likewise, [PERSON] et al. [5] found that, for barley seeds (_Hordeum vulgare_ L.), all exposure times showed an improvement in the sanitary quality of the seed.