Answer:
Blue light
Adding 10-20% blue light allowed plants to grow much healthier, with a compact appearance. There is also far-red light which is has wavelengths that are lower than normal red light–similar to near-infrared wavelengths. Far-red light helps the plants produce greater yields.
The answer is; Benedict’s reagent
It is used to test for reducing sugars. In presence of these sugars, the reagent, that is blue in color, turns different shaded of red (to brick red), depending on the amount of reducing sugars in the solution. It is important to note that the solution has to be heated.