Xi,

I cannot answer either question, but I suspect it lies somewhere in
the fact that there are multiple processes going on in a plant:
photosynthesis (requiring light, obviously) which converts absorbed
water and carbon dioxide into sugars, a respiration process that
converts those sugars into ATP, the true "fuel" by which the plant
lives and grows, and then whatever processes go on to create more
cells to physically grow.

It wouldn't surprise me if there was some sort of "competition for
resources" going on that favors one process over another in different
lighting conditions, or maybe it's a heat dissipation thing...

--

Ray Barkalow - First Rays Orchids - www.firstrays.com
Plants, Supplies, Books, Artwork, and Lots of Free Info!
..
"Xi Wang" wrote in message
news:zVQBd.678603$%k.637216@pd7tw2no...
Hi list,

Thanks for the many replies. A follow up question has occured me
then. It was mentioned that I should cut back to 14-16 hours because
if I hit them continuously with light, they may not flower. But
when they are just growing in the summer and not flowering anyhow,
would more light promote more growth?? Someone also mentioned that
beyond 16 hours, the extra light would just be a waste, why is that
exactly?

Cheers,
Xi