Well the interesting thing about these questions that start to bridge subjects together (in this case maths and plant biology), is that there could indeed be a study or have been studies for this kind of thing in the past or ongoing as we speak. I think its certainly a concept worth looking into, from what I know of occult reading many texts from all kinds of cultures and periods in time do mention the effect and potency of the moon on plants and water.
Although this in a way is already happening except with the sun and not the moon, the moon only really has an effect on the tides and its 'moonlight' is only really reflected off the sun, whether the suns light passing through the moon causes it to change thus changing the properties of the plant as a way of testing it, hasn't as yet been thought of.
But when the suns rays hit the the plants surface during the day, they do cause the cells in the plant to 'change' or 'react' in response to the sun rays, feeding nutrients to the plant so it can survive. Maybe in some small way moonlight might cause come subtle change, but plants tend to go into night mode when the sun goes down and it becomes nighttime. The best time to harvest however is just after summer towards the start of fall! Although that depends on what you are harvesting, in that if it depends on the seasons then fall. But if your growing plants/crops they can be done at all different times of the year or under different conditions.