Today I read that that Gibberellic Acid (often called GA or GA3), a powerful plant hormone, can be used to induce germination in seeds that haven’t been thermally stratified. This could be quite helpful for a project I’m working on. (I’ve written about bits and pieces of this in the past and hope to write a post sometime soon explaining the big picture behind the project.)
The drawback seems to be that handling the GA correctly (e.g., successfully dissolving the GA3 in water and getting the concentration right) can be a bit tricky. GA is also quite expensive, although the flip side is that not much is required as the correct concentration is quite low.
Does anyone here have experience with GA? What was it like using it? For example, how well did it work and what are pitfalls to avoid?
Several sources sell GA through Amazon. One of them includes the following instructions in the product information section:
Dilute the GA3 powder; the GA3 powder is very hard to dissolve just by stirring in water alone. Proper dissolving can easily done by adding very small amounts of alcohol to the GA3 being used until the powder is dissolved (this very small amount of alcohol will not hurt your plants). The dissolved powder than can be added to the distilled water to produce the proper PPM dilution. (See chart below) Also recommended is the addition of a wetting agent; a few drops of agriculture soap can be used. It is very important to remember proper PPM dilution rates for success. Too much GA3 or too little can affect your end results. The GA3 needs to be applied in early morning before sunrise if possible. Bright sunlight will effect GA3, making it less effective or destroying its effect completely. Only mix what you’re going to use that day. The powder can spoil in high heat and will only last about one week once mixed. Wrap the unused powder container in aluminum foil to protect from direct sunlight. If stored in a cool, dry place, the powder can store for up to 2 years. Do not freeze or refrigerate. GA3 Powder 90% is soluble in 70% common rubbing alcohol. Before it can be used is must be turned into a liquid. The amount of Gibberellic acid that needs to be used is very small. Drop the correct amount of powder in a small bottle, then add a few drops of rubbing alcohol. The only reason to use alcohol is to dilute the Gibberellic acid powder. Use just enough alcohol to wet the gibberellic acid powder. If after a couple of minutes you can still see some powder, add a few more drops of alcohol. Then just add water to get the right concentration. It is often said that alcohol will damage plants, but not in the very low concentration needed to dissolve Gibberellic acid. 90% GA3 powder will not dissolve in water.
You’ll notice that it says “The GA3 needs to be applied in early morning before sunrise if possible.” The reason is that GA is not only useful for breaking the dormancy of seeds, it also apparently is a major growth accelerator for plants.
While the description of how to use GA is meant for people using it as a plant growth promoter, I’ve included it here because as you can see it needs to be handled and used in some fairly specific ways.
If you need to break dormancy for apple seeds and cooling is a problem, GA might very well be what you need.
BTW, how do you trick the apple trees into thinking they’ve gone through a winter chill period so they’ll bloom and produce without the winter chill actually having happened? Also, how does disease and insect pressure in the topics compare to typical North American conditions?
There are some good things about growing apples in the tropics; no frost damage, no fireblight, no codling moth, no stinkbug. Insect and fungal damage is surprisingly minimal; bird damage to the apples seems to be the biggest challenge, followed by underground termites from hell.
Since the growing season is all year long, can one get two (or even three) harvests per year?
I had a Carmine Jewel (U. Sask. cherry) get a nasty plant fungus that basically totally defoliated it. When it grew a new set of leaves I was surprised to see that it also flowered again. It would have produced a second crop of cherries if the season had been longer; the cherries were only babies when cool fall weather set in.
Yes, Anna and Dorsett Golden bear two crops, the main one in the photo is harvesting around now and a smaller one in September. After harvesting the second crop they defoliate the tree and it starts all over. Other higher-chill varieties take longer to wake up after defoliation and don’t produce as big a second crop, just a few smaller apples.
The guy in the photo picked 7,000 apples this spring and sold them immediately. He wants 1,500 more trees ASAP, and will try increasing the density in the orchard rows.
@applenut and @ILParadiseFarm, IIRC, while reading a little bit about this topic, I found some information on how the necessary GA concentration varied with fruit type. In particular, GA-treated apple seeds were reported to have germinated with no thermal stratification at all at a particular concentration. It seems that the effects are very concentration dependent; both too little and too much either won’t work or won’t work in the way intended.
While I don’t have time at this moment to track the concentration info down, it is on the Net somewhere out there.
Also, @ILParadiseFarm, if you may be going to do more experiments with GA in the immediate future and would consider treating some seeds for me (e.g., if I give you some of the seeds or something else in return and / or pay for the GA cost), please send me a DM. I have some non-stratified seeds that would be nice to get started if I could do it within the next month or so and let them get a bit of growth in this year.
I am looking for a time for peach seed germination. I put some Lovell peach seeds in a container, so I could do this in one step process. They have been in the fridge for 2 months. I have seen on the internet it could take up to 3 months. When would be a safe time to take them out?
