The challenge has been taken up by Purdue U. to develop a self-sustaining ecosystem for space. They intend to use plants for nearly everything, not just food production, but also oxygen production, air filtration, and waste recycling. They still intend to use artificial lights which surprises me since sunlight is free and can be filtered for the right wavelengths, whereas artificial lights produce mostly heat. Even though they are somewhat convenient they are hugely inefficient. Dropping light strips between plants will ensure that branches near the base of the stalks grows as bushy as near the top (no more light-blocking canopy), although making the plant bushy near the bottom might make harvesting more difficult. There are just so many variables in this issue, but I can't imagine why artificial lights would be a simpler, more effective, and more robust source of energy than the Sun?!

Space.com Article