Heat Treatment Delays, Doesn't Reduce Germination?

[Nan_PA_6b]

Previous studies have shown that heat-treating tomato seeds at 122F for 25 minutes will destroy diseases inside the seeds, but also reduces germination percentage.

I own a sous vide' machine, which holds a circulating water bath at a precise temperature. I wanted to see how badly germination would be reduced after heat-treating seeds.

I cleaned a batch of Hardin's Miniature tomato seeds by the Oxiclean method. After they had dried for 4 days, I separated the seeds into 2 batches. One batch received no treatment, the other received a heat treatment in a sous vide' bath. The heat treatment seeds were put into an organza bag, and put into a hot water bath at precisely 122 degrees F for precisely 25 minutes. The wet seeds were allowed to dry for about 4 hours.

Then, 17 seeds of each batch were planted, one seed per cell, in a seed starter tray, in the same medium. 17 seeds was the chosen number because the starter tray rows were 17 cells long.

Here are the germination results:

Day___ heat batch____ no heat batch
7_____ 10_____________ 0
8_____ 11_____________ 0
10____ 12_____________ 2
13____ 15_____________ 6
19____ 15____________ 13
20____ 15____________ 15


The results suggest I mislabeled the rows, so the heat-treated was labeled "no heat" and vice versa. But either way, the germination rate for both heat-treated and non-heat-treated seeds was 15/17= 88%.

One of the batches reached full germination in 13 days, the other in 20 days. If the heat treated was actually the batch that was slow to germinate, previous studies may have not gone on long enough to notice the late germination. They would conclude that germination was reduced.

My results suggest that I can heat treat my seeds and get decent germination. Germination testing will be difficult, as it will take about 3 weeks. I don't know if one can germ test in a wet paper towel for three weeks?

So, if you were to receive seeds from me, would you prefer to have heat-treated, slower to germinate seeds, or not heat-treated, quicker to germinate seeds?

Discuss...
Nan