A. Success depends on how much sunlight plants get when leaves are out. When leaves are gone, sunlight is not nearly as important. Winter sunlight is not terribly important for trees in our climate because it is cold and the plant is dormant or "resting". But light during spring and summer months, when leaves are out, is very important. That is when sunlight is critical.
Fruit production is usually not controlled by an "on and off" switch. As the total amount of light decreases, the amount of fruit produced also decreases. At some point, if the plant does not receive enough light, flowering and fruiting stops. The amount of sunlight needed for flowering and fruiting varies somewhat among plants but fruit trees generally need a minimum of 6 hours of direct sunlight. If sunlight continues to decline during months when leaves are out, at some point, there won’t be enough light for the plant to make flowers and produce fruit. It stops producing fruit, only leaves and stems.
If a fig tree is getting a minimum of 6 hours of sunlight when leaves are present, it will probably produce decent fruit. Not all this light has to be direct sunlight. Reflected light also counts but not as much.In direct light, light from bright reflecting surfaces, will contribute to flowering and fruit production but more indirect light is needed than direct light. Much of this depends on the total amount of light as measured in footcandles per hour or watts per square meter per hour. The quality of light, the color, is also important because it can trigger some types of behavior in plants.Fruit production also depends on the “quality” of reflected light. If light is reflected off shiny or white surfaces, then plants receive more light than light reflected from darker or variously colored surfaces.