Chloroform Improves Tomato Seed Germination
 

Tomato 'Red BrandyMaster' seeds that were packed for 2016 and stored for five years in a refrigerator were used for this experiment. 17 seeds were soaked in chloroform for 1 hour and dried for 0.5 hours before planting on 3/1/21. Also, 17 untreated seeds were planted as controls. Photos will be taken and posted as time progresses. Controls are on the left halve of tray and treated seeds are on the right half of tray.

3/10/21

So far, 3 treated seeds and 0 untreated seeds have germinated.

Answers to Obvious Questions
This was discovered by accident by SK Ries in the 1970s who used chloroform as a solvent to apply 1-triacontanol to tomato seeds and noticed improvement in the controls that were treated with chloroform without triacontanol. I lost the exact reference.

Shortly thereafter I did experiments to confirm this but did not document my results. I tried other solvents on tomato seeds without improvement. I also tried chloroform on other seeds without improvement.

More photos to come.

Re: Chloroform Improves Tomato Seed Germination
 

3/11/21



So far, 14 treated seeds and 8 untreated seeds have germinated.

Re: Chloroform Improves Tomato Seed Germination
 

3/12/21



So far, 16 out of 17 treated seeds and 12 out of 17 untreated seeds have germinated.

Re: Chloroform Improves Tomato Seed Germination
 

It can also improve an otherwise bad date...

In all seriousness though, that is an interesting experiment. So I have to ask, where did you get the idea? :confused:

Re: Chloroform Improves Tomato Seed Germination
 

I read your mind and answered your question before you asked it at the beginning of this thread.

The results of this experiment are not nearly as impressive as I remembered it from the 1970s so I am repeating the experiment with 13 and 21 year old tomato seeds that were stored in my basement (as opposed to a refrigerator). If any of those seeds germinate (which will surprise me), I will post the results. Otherwise, you can assume that those experiments were failures or I am dead.

Chloroform might improve the germination of seeds of tomato relatives such as eggplant or potato. Yes, I know that potatoes are not typically grown from seeds.

Re: Chloroform Improves Tomato Seed Germination
 

The final result for the above is that, for both treated and untreated seeds, the 16 out of 17 seeds germinated. The only effect demonstrated was earlier germination and a decrease in the variance of time to germination for the chloroform treated seeds.

NEW EXPERIMENT:

On 3/14/21, I treated 21 year old tomato 'Better Boy' seeds and 13 year old tomato 'Giant Tree' seeds, as before, but planted 25 seeds of a kind in the same containers. These seeds were aged in my basement instead of a refrigerator. In the following photos, the top left container is untreated Giant Tree, top right is treated Giant Tree, bottom left is untreated Better Boy, bottom right is treated Better Boy.

3/28/21:



So far, only 5 treated Giant Tree seeds have germinated.

Re: Chloroform Improves Tomato Seed Germination
 

3/14/21: Seeds Planted.

3/28/21:
Giant Tree Untreated - 0 out of 25 seeds germinated
Giant Tree Treated - 5 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated


3/29/21:
Giant Tree Untreated - 1 out of 25 seeds germinated
Giant Tree Treated - 7 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

3/30/21:
Giant Tree Untreated - 2 out of 25 seeds germinated
Giant Tree Treated - 7 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

3/31/21:
Giant Tree Untreated - 2 out of 25 seeds germinated
Giant Tree Treated - 8 out of 25 seeds germinated (One seedling is dying, maybe, of damping off disease.)
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

4/1/21:
Giant Tree Untreated - 2 out of 25 seeds germinated
Giant Tree Treated - 9 out of 25 seeds germinated (One seedling is dying, maybe, of damping off disease.)
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

4/2/21: No Change

4/3/21:
Giant Tree Untreated - 2 out of 25 seeds germinated
Giant Tree Treated - 10 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

4/4/21:
Giant Tree Untreated - 2 out of 25 seeds germinated
Giant Tree Treated - 11 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

4/5/21:
Giant Tree Untreated - 2 out of 25 seeds germinated
Giant Tree Treated - 12 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

4/6/21:
Giant Tree Untreated - 3 out of 25 seeds germinated
Giant Tree Treated - 14 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

4/7/21:
Giant Tree Untreated - 5 out of 25 seeds germinated
Giant Tree Treated - 14 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

4/8/21:
Giant Tree Untreated - 10 out of 25 seeds germinated
Giant Tree Treated - 16 out of 25 seeds germinated
Better Boy Untreated - 0 out of 25 seeds germinated
Better Boy Treated - 0 out of 25 seeds germinated

4/9/21: No change.
4/10/21: No change.
4/11/21: No change.
4/12/21: No change.
4/13/21: No change.
4/14/21: No change.
4/15/21: No change.
4/16/21: No change:

Re: Chloroform Improves Tomato Seed Germination
 

Conclusion:

None of the 21 year old tomato 'Better Boy' seeds germinated.

Of the 13 year old tomato 'Giant Tree' seeds, 10 out of 25 (40%) untreated seeds germinated and 16 out of 25 (64%) treated seeds germinated. The average time to germination for the 10 untreated seeds that germinated was 22.7 days. The average time to germination for the first 10 treated seeds to germinate was 15.5 days. Thus, chloroform treatment increased the germination rate by 60% and decreased the average time to germination (of the seeds that germinated) by 32%.

Re: Chloroform Improves Tomato Seed Germination
 

There are two conflicting hypothesis to explain why chloroform improves tomato seed germination:

1. As a solvent, chloroform removes growth inhibiting substances from the seeds.

2. Residual chloroform in the seeds stimulates growth.

Many years ago, I tried a wide variety of other solvents, including carbon tetrachloride, without improvement of seed germination, thus, showing that hypothesis 1. is very unlikely. Now, to prove hypothesis 2., I performed the following experiment:

Using Ramapo tomato seeds, packed for 2015 and stored in a refrigerator, I placed 6 seeds in each of 4 Petri dishes, labelled 0, 1, 2 and 3, on 1/16/23. Then I added 2 ml of water solutions of chloroform to each Petri dish as follows:

0 - pure tap water (control)
1 - 1000 ppm choroform
2 - 500 ppm choroform
3 - 250 ppm choroform

Some of the seeds began germinating on 1/20/23. The following photo was taken on 1/21/23:



This photo shows that 1000 ppm of chloroform inhibited germination but 500 ppm and 250 ppm stimulated germination, thereby indicating that hypothesis 2. is correct. This is good news because it is more practical to apply choroform as a soil drench. Also, it indicates an auspicious opportunity to experiment with foliar sprays of chloroform to stimulate the growth of established tomato and possibly other plants.