how do orchids control when they release fragrance?

[orchidsarefun]

you can apply the same basics to human behaviour. A male or female going out on the town is going to spruce up. However if you are going to spend the day at home, you are unlikely to shave, or apply make-up....get dressed up.
Its to do with when you are likely to meet a mate !

[Cattleya17]

That was a cool article!

[kavanaru]

Originally Posted by DavidCampen

"Flowers give off their scent without any visible external stimulus. They control the scent release by an internal biological clock which is particular to each species. Environmental factors, including light intensity, day-night cycle and temperature, act as triggering or inhibiting impulses ..."
The Scent of Orchids, Roman Kaiser,1993, Elsevier, Amsterdam, ISBN 0-444-89841-7

Isn't light intensity a visible external stimulus?

Some plants migh control scent release via intnal clock, ohers just don't... E.g. Angraecum didierii is fragant during the night... If you turn on the light in your greenhouse, it will stop being fragrant after few minutes...

[dabblin-n-orchids]

to answer the above question about why certain species/genera are fragrant and why others are not all comes down to pollinators again. Some plants rely on scent cues whether they indicate food OR (and this is one of my favorites) the fragrance of the orchid has evolved to smell like a fertile female of the the pollinator species. the orchid thus lures in very confused males to pollinate them. many other flowers rely on visual cues and those that do, especially bee pollinated species, often contain pigments that fluoresce in the UV spectrum and are invisible to humans but can be perceived by bees and other organisms.

[Leafmite]

Are there cultural practices that increase or decrease an orchid's ability to produce fragrance? Just curious. I have never seen this addressed.

[johnblagg]

some respond to temperature differences and some to light being absent .... other possibly a combination of both if they only do so in early morning or later in the day after it is warmer

[Leafmite]

I have a hard-cane dendrobium that has, in the past, bloomed with fragrant flowers but, in the past few years, the blooms have been unscented. It always gets the same lighting (this one loses leaves in protest if it doesn't). If anyone has any ideas....

[james mickelso]

Indeed this function is controlled by a biological clock. A gene. Or should I say a large set of genes. I have an orchid, epidendrum ciliare that is fragrant at night. It's pollinator is active at night. It is intensely fragrant at night so I theorize it's pollinator is scarce. Other orchids I have are fragrant at different times of the day. And regardless of the temperature or light level. And yes, our hybridization of orchids has greatly reduced some orchids ability to produce fragrance.

[lepetitmartien]

Leafmite, I'd look into something missing to the orchid, not necessary for growing and flowering but for perfume yes.