Oct 9, 2013

The Effect of GA3 on Lathrus odoratus, Bouquet

For the past two years I have been experimenting (amateurishly) with Gibberellic Acid as an aid to seed germination. The effect, depending on the genus and species, has been enlightening. I sow several hundred kinds of seeds in any given year and I treat mainly, but not exclusively, those that are reputedly difficult to germinate. I generally divide the seeds into two equal parts and soak them overnight, or up to 24 hours, one half in distilled water and the other half in a 500ppm solution of Gibberellic Acid. Both groups are then treated exactly the same as regards soil, moist, heat, light, etc. In some cases I could discern no visible difference in germination or growth. in others it may actually have had a detrimental or deleterious effect, but in more than a few the results appear to be positive, both in shortening the length of time for germination to occur, and in the number of seeds germinating. I will try to compile a list and brief summary of my finding thus far at a later date.

Because of our physical location - 90 days frost-free, perhaps a few more the last few years due to you know what, and living in a frost pocket I start most seeds, even many fast growing annals, indoors. Yes, it gets a little crowded at times.

Lathrus odorous, the sweet pea, germinates readily but this spring, because I had mixed extra GA3 I decided to treat some of the sweet pea seed.

I keep a comprehensive record (at least I start out that way) of difficult or rare seeds, but for the annuals, and a good percentage of the 'common' perennials I keep almost no notes of their progress. If for some reason I have used GA3, or some other method to treat the seed then I do make an effort to at least make sure growing conditions are the same until they are planted out in the garden. With so many flats of seedlings it is difficult to keep track and a few get overlooked for a time. Thus it was for the Lathyrus odoratus.

For weeks I had been mentally reminding myself there were several flats of seedlings that simply had to be planted out as they were rapidly becoming pot-bound. One day I realized I could wait no longer and began to carry plants to various parts of the garden to be planted. When I came to the sweet peas I had quite a surprise. Half were healthy looking plants while the others reminded me of Jack and the Beanstalk. The stems were elongated and the leaves smaller and narrower (see picture). There were three 6-packs of each and after checking my records (I number all plant trays etc.) the obvious was substantiated. I don't recall whether GA3 had speeded or enhanced germination, and at the time of thinning I apparently noted no difference, but it certainly seems to have had an effect on subsequent growth. I only regret not planting out the GA3 treated plants to see what the final outcome might have been. In other cases where GA3 has had a beneficial effect regarding germination, subsequent growth differences have not been noted, but I have not looked that closely, which leads me to believe any differences in growth after germination are slight, if any. But, I am going to take a closer look, once it stops raining.

I am reminded yet again, you can never take enough notes!

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