## 1 Introduction  
Laser technology can be a convenient option to be incorporated into systems of agricultural production. Therefore, more attention was given in recent years to physical factors that may be applicable to processing of sowing material [1; 2]. In order to ensure a high seed performance, various methods of processing are used, including chemical preparations, such as seed inoculation by chemical material and growth regulators, as well as physical factors, including laser light and magnetic fields [3; 4; 5; 6; 7; 8]. Pre-sowing treatment was applied in order to stimulate the seeds to better germinate and grow faster in various sowing conditions [9]. The use of physical factors for controlling the influence of biological behavior during development and storage of different cultures is a modern trend in combining the intensification of plant technologies with ecological requirements [10]. Most physical factors that only modify physiological and biochemical processes in seeds are also safe for the environment [11; 12; 13], for instance, improving agriculture practices, such as by using chemical fertilizer and regular weed control [14]; however, this can affect the environment [15]. In contrast, laser stimulation does not cause harmful changes in the environment, which is of great importance in organic and integrated agriculture [16; 17].  
Light is an essential condition for photosynthesis and is needed in plant improvement; it can also affect the seed field performance, growth, and yield of some plants [18; 19; 20]. Among the previously used methods of seed refining [21], light laser is a physical factor that does not cause adverse changes in the environment. Research on the effects of pre-sowing bio-stimulation on plant crops showed that the best results of this treatment are obtained for plant vegetables, rather than for cereals and root crops. After applying radiation laser to tomatoes and cucumbers, a significant increase in yield was found, which accelerated the ripening and produced better fruit quality [8; 22]. One of the methods of seed refinement is irradiation; a divergent beam laser light provides energy to modify physiological and biochemical processes, causing an increase in the field's performance to rise and yield crops [23].  
Previous work on the effects of pre-sowing seed stimulation with laser light concerned annual plants [24]. Laser stimulation is a physical phenomenon; it depends on its ability to absorb and store the light energy of plant cells and tissues. In the case of seeds, the same phenomenon can be observed; they absorb energy light, transform it into chemical energy, and use it at a later time [3].  
The research conducted so far on the laser stimulation of plant seed agricultural and horticultural products shows that it may affect the enzymatic system, accelerating the decomposition of starch, the germination of seeds [25], photosynthesis, and transpiration efficiency [10; 26; 27], as well as plant growth and development [28; 29; 30].  
For this purpose, maize was selected as a model plant due to its significant economic value as a worldwide cultivated crop for its high starch content [31; 32]. Furthermore, studies revealed that the laser is useful to improve the sanitary quality of maize seed [33]; this characteristic allows a seedling to have more strength to emerge from the soil [34].  
The phenomenon of laser radiation is still poorly understood; there are only fragmentary studies or hypotheses that attempted to explain how laser light interacts with seeds [35; 36; 37]. So far, no studies were done on the effects of different wavelengths of laser light (i.e., blue, green, and red wavelengths) on maize seeds. Therefore, the aim of the study was to determine the effect of different doses and different wavelengths of laser irradiation for maize seeds during pre-sowing treatments in terms of yield value.