Anyone using GA?

I’m thinking of trying GA treatments to promote germination of my seeds this year. Has anyone tried it? I’m thinking of just trying it in different concentrations on different batches of OP seeds and seeing what works best, and if there are any side effects.

Joseph

I haven’t tried it, but I’d think that the hard part would be getting the GA through the thick hard waterproof seed coat. Perhaps some sort of scarification would help. Acids, enzymes, and Oxiclean have been used for scarification of rose seeds. If you can find a way to get chemicals through the seed coat, there are other chemicals that have been reported to be better than GA at breaking dormancy in members of the rose family (Rosaceae), for example, potassium nitrate and thiourea.

Link: www.ipgri.cgiar.org/publications/HTMLPublications/52/ch47.htm

This is a bit off topic, but my curiosity is getting the best of me. Do many of you really have great difficulty germinating your seeds, so much so that you have to seek out these labor intensive treatments to enhance germination? I rarely get less than 50% germination from most of my annual crop, regardless of parentage. I can’t imagine needing to get a higher germination rate than I already have. Its not worth my time and energy to pursue these “extreme” treatments. So, tell me…do some of you really have such low germination rates that you find this necessary, or is this just the pursuit of science?

Paul

Joseph,

Some people have had good results with GA. I tried it in 1979 or 1980 and had a disaster. That is, average germination dropped from 30%+ to about 1% or 2%, and the new seedlings–the few I got–would die slowly, with the stems turning a translucent brown from the root up. I finally figured out that whatever was causing the deaths was accumulating or had accumulated in the rapidly dividing cells of the root tip and killing it before moving upward, and I managed to save most of the few seedlings that germinated after that by the simple method of breaking off the bottom half of the seedling when it first germinated. It was slowed a bit while it formed a new root, but at least I didn’t lose the seedling. I wrote about this wonderful experience for the RHA Newsletter. I think the title was “Radical Radicle Surgery.”

In short–

If you don’t need the GA, don’t use it unless you simply want to investigate it and have some seeds to spare.

If you do use it, be careful to duplicate the conditions of the successful experiments you’ve read about. Most of us don’t have the conditions to duplicate lab results.

I tried GA in 1989 and from what I remember it didn’t contribute to better germination- I got about the same.

This past winter I was testing GA on another species (in the Asteraceae family) and had poorer germination than the water control. The recommendation was to dissolve the GA in a little ethanol and bring up the concentration with water. I tried again without the ethanol. I was using a relatively low concentration (500ppm) and stirred and stirred and the GA3 powder finally went into solution and I used that on this species. The germination results showed now that this GA treatment wasn’t significantly different than the water control. For those of you who used GA and found poor results in roses, did you use ethanol? I don’t remember if I used ethanol or not to get the GA into solution in 1989.

Paul, yes germination can be a challenge for me too with some germplasm more challenging than others and some years more than others as well. I think my climate has a lot to do with it and not routinely being able to hybridize in a greenhouse. Gudin’s early 1990’s article in HortScience revealed that cooler temperatures during especially the early part of seed development results in a thicker endocarp within the seed and ultimately reduced germination. Also in MN the season is often cut short and I need to pick some hips before they are fully ripe if a hard freeze is predicted, and immature seed seems to have reduced germination as well.

Sincerely,

David

As a partial answer to Paul B question. My experience with enzymes is that they speed up germination but do not necessarily increase the % germinated. To someone in a cold zone this is beneficial as seeds germinated too late in the season may have a lower chance of surviving the winter.

What about starting the germination in late fall? One year I started germinating in late fall. At the time I was very happy that it happened only to find, come spring, that it was too cold to plant out and the large seedlings were taxing my space restrictions.

Thus, quick, high germination in as short a time period is what I am striving for as I periodically adjust my technique.

Ahh, thank you Henry and David. I hadn’t taken these issues into account. Now that makes more sense. Thanks.

Paul

Yes, anything that will speed up germination and or make it more uniform (with less mold) will be beneficial to me. I have had seeds that I think were viable but lost them to mold. I’m still working out what my ‘good’ parents are and still am trying some difficult ones. I’m working with a small amount of hips, so every seed counts. Last year, I was new to moving seedlings and lost the first few. Turns out only one cross only had 1 seedling out of about 9 seeds germinate and it was one of the ones I lost. I’m hoping that treatments may give me improved seedling germination.

Chris Mauchline

zone 6, SE PA

My GA experiments with control are plotted at thw following link:

http://home.neo.rr.com/kuska/gibberellicacidmine.htm

Link: home.neo.rr.com/kuska/gibberellicacidmine.htm