Truly sorry King Cauli if i've caused offence, it was meant to be lighthearted. It is the banter on this site, as well as the characters and the in depth knowledge, that make it my favourite lotty site. Sorry you thought I was talking (well rotted horse on straw preferably) s..t when all I was doing was supporting unbiased research by Ice (cool lady) and implying my own scepticism. I haven't taken offence, i've taken it as an invitation.
The moon has two noticeable effects on the earth, gravitational and reflecting sunlight at night.
The gravitational effects of the moon on a seed must be too minute to have any effect, and vary by the hour. If the moons gravity had any measurable effect on small bodies then dieters the world over would be climbing the walls with frustration at their yo-yoing weight (actually now I think about it ......!!!)
The light of even a bright full moon is too weak to have any effect on a plant's rate of growth (refer to any supplier of grow lights re lumens m2). However in the spirit of open mindedness I am aware of a mechanism where moonlight could influence a plants behaviour. Some autumn flowering plants that seem to respond to shorter days are in fact responding to longer nights and require (typically 12) hours of darkness to trigger the production of hormones that induce flowering. It is therefore possible that a bright full moon at a critical period could have an influence on flowering times of some particular plants, however I think that there are too many variables to link any such (marginal) effect back to day of sowing.
I suspect (my hypothesis is) that this is no more than association being mistaken for cause and effect along the lines of:- I sow my seeds on Saturdays (main lotty day), I am pleased with my harvests (chuffed to little mint balls actually), therefore seeds should be sown on Saturdays. If your moon sown produce is better than others its more likely to be because you are a better grower. Anyway its always interesting to come across different ideas: makes for more interesting debates.