Light is an important regulator of plant growth and development. The application of LEDs to the plant growth system.
The studies that have been performed since that time suggest that plant species differ in their responses to LED treatments and exhibit a high degree of morphological and physiological plasticity to changes.
Besides, there are some reports on the effect of light on Stevia seed germination it is still a phenomenon how different light wavelength modified Stevia development.
Abdullateef and Osman(2011), Kumar and Sharma (2012) reported that light is a positive stimulator of Stevia seed germination.
Also in our study, germination of Stevia seeds was greatly inhibited by darkness.
These observations demonstrate that Stevia belongs to the positive photoblastic species.
Seeds of that species not only require light to germinate but also the proper spectral composition.
Abdullateef and Osman (2011) found that germination potential of Stevia seeds was enhanced by red light, compared to white light. A different reaction was observed at presented experiment where LEDs light were examined.
Red LED light, under the majority of the tested conditions (temperature, substrate), exhibited an inhibitory effect on Stevia seed germination compared with other LEDs and WF light. In our study the best effect on germination was exerted by B LED light (50% of germinated seeds at25◦C, on AG substrate).