South African Bulbs 2013

[Darren]

Pontus:

I believe the "kirstenboch smike (smoke water) water" is a solution made from paper that has been impregnated with fumes from a fire.  The paper is place in water and the constituents from the smoke paper are transferred to the water.  Bulbs are watered with the  it and it  simulates the effects of fire in initiating flower product in bulbs.

Quite correct. You can buy the impregnated papers from Silverhill seeds at a reasonable price.

Alberto is also right - the bulbs need to be mature before you start to think about smoke treatment.

[Maggi Young]

I need to pay more attention  -
I thought that the smoke method was only to help germination of seeds..... 

[Ezeiza]

It serves both purposes (and possibly others we are not aware of). Basically, the smoke indicates the plants and dormant seeds that the ground has been cleared and fertilized for further action. In years with no fires the ground is so choked with vegetation that it would be a great waste to flower and produce seed that would have no chance to germinate.

[Darren]

The ecology of these triggering mechanisms is quite fascinating. It is also likely that, besides direct stimulation from chemicals in smoke there are other triggers resulting from fires such as:

Sudden release of a nutrient pulse from rain washing combustion products down into the soil - especially mobile nutrients such as N and K.

Changes in pH

Changes in temperature (either absolute or relationship between day/night temps) due to more sunlight hitting the ground during the day and/or colder nights due to less shelter allowing greater radiation of heat during the night.

[Ezeiza]

We once tried the smoke treatment on several Mexican Zephyranthes and they responded by flowering sucesively for an abnormally long time. But, there were no flowers for the three following years from them after that.

[ArnoldT]

Darren:

I'm with you.  I think these triggering mechanisms are also fascinating.

I have a copy of The Physiology of Flower Bulbs, by Hertough and Le Nard.

The are a number of references in the book. 

1. Freesias corms were released from dormancy using  smoldering rice hulls.  Trigger was believed to be either ethylene or CO2.
Treating Freesia corms with 1ppm of ethylene for 6 hours  was significant to break dormancy. The discovery of smoke on initiating flower bulb growth is listed at 1916 by Molish.

2.N. tazetta's were flowered using "burning over" with smoke of ethylene treatments. Wolfe and Horton 1958.

3. Dipping in solutions ethylene chlorhydrin was also used.

[Maggi Young]

If ethylene is beneficial in this way, who has tried  keeping bulbs and/or seed in close proximity with ripening bananas ??

[johnralphcarpenter]

How about leaving a banana skin on top of newly potted bulbs?

[Darren]

If ethylene is beneficial in this way, who has tried  keeping bulbs and/or seed in close proximity with ripening bananas ??

This trick has been used for quite a while by growers of native terrestrial orchids in Australia. Some Caladenia and related genera are especially stimulated by ethylene from bushfires. The growers place the dormant tubers in a bag with a banana skin for a period of up to 3 weeks (changing the banana skin every few days before it gets really disgusting!).

I've never tried this as I don't grow any affected species, though I do grow Microtis unifolia which apparently does not need fire stimulation to flower but certainly is boosted by it. My plants rarely flower so I may give it a go next summer. Will need to volunteer Susan as banana-eater as I don't actually like them 

[jshields]

A few years ago, someone reported isolating a compound from smoke that had activity with plants.  This was an organic molecule larger than ethylene.  This might be what is in the smoke paper.  Ethylene is a very volatile gas and would not be retained at all by paper, not even by very absorbent paper.  I do not usually think of ethylene as a growth stimulant.  It is more likely to cause wilting of flowers or transition of a growing plant into a dormant state rather than to stimulate a dormant plant.  It ought to be pretty easy to test ethylene's action on dormant bulbs in a greenhouse.  I would be very interested in hearing what the results are.

Jim

[ashley]

I'd agree about ethylene being too volatile Jim. 
According to Wikipedia a class of furanone/pyranone derivatives called karrikins are responsible (cyanohydrins too), but I haven't delved into the literature.
This article is quite interesting as a lead-in.

[SJW]

Grateful if someone could confirm whether this is Polyxena (Lachenalia) ensifolia...

[ArnoldT]

Steve:

Graham Duncan has it in his book, The Genus Lachenalia as Lachenalia ensifolia.

I couldn't begin to explain why.

[SJW]

Steve:
Graham Duncan has it in his book, The Genus Lachenalia as Lachenalia ensifolia.

Thanks, Arnold. I'm not too familiar with Polyxena so thought I'd check. The PBS website images usually helps with ID but on the Polyxena page I just got confused with the differences between ensifolia and pygmaea! A kind forumist let me have a bulb of the latter and that is in bud so I'll be able to compare the two in a few days.

[Ezeiza]

Ethylen triggers the flowering in bromeliads. The classic method is to put the potted plant in a plastic bag with a rotting apple for a day or so and this seems to be enough.

Jim is right about it stimulating dormancy in bulbs. Ethylen from drying leaves stimulate the bulb to go dormant.