The amount of sunlight that plants can use for energy changes depending on how bright it is and how long the day is. In Texas, during long sunny days, plants can use up to 58% of the sunlight for energy, while during short days, they can only use around 50%. The researchers found that the type of sunlight that plants can use the most is between 400 and 700 nanometers. They also created equations to estimate how much usable sunlight plants can get based on how bright it is and the time of year.