Who’s a towel doofus? Not who, but what! Read on the identity will be revealed…

As I explained two weeks ago,  I want to germinate maize kernels on the surface of agar medium, held in a vertical Petri plate. Simple, right? I thought I could just put a sheet of brown paper towel over kernels and agar; but no, the germinated roots got stuck, unable to plow through the space between the agar and the towel. Sigh. So for the next experiment I unleashed the towel doofus.

Likewise made from a brown paper towel, the doofus is rolled up into a tight cylindrical wad, soaked in water, blotted dry, and then laid over the row of kernels. Then, I replace the top of plastic Petri plate and the doofus is squeezed onto the kernels, holding them in place. No part of the doofus extends above the kernels to interfere with the shoot or below to hassle the roots. Nice and clean.

Three days after setting up the first doofus-containing plate, I was delighted to see a crop of long and straight roots heading down along the surface of the agar. My happiness was short-lived. I transferred six or so of the choicest seedlings onto a fresh agar plate, put a wet rectangle of towel over the roots to hold them up, and launched a movie. The next day, I returned to discover that, yet again, the towel had frustrated the roots. They had grown only a millimeter or two. They should have grown 2 cm.

The roots were not the only thing frustrated. What is going on? I checked my notes. In the first four experiments, roots grew fine between agar and towel but in the next few they were stopped in their tracks. I noticed that for the first four experiments, kernels were germinated in jelly rolls but for the frustrated ones, they were germinated on agar. Well, well, there’s a correlation. Maybe something about life inside a jelly roll prepares a root for making headway between towel and agar?

That doesn’t seem … impossible. But anyway, there was an easy way to test it. Germinate some kernels in a jelly roll, germinate others on agar beneath a doofus. Transplant some of each onto an agar plate and cover the roots with a towel. And see who is frustrated. And that is what I did.

This figure shows the last image of the movie, 16 h after starting the experiment. It is not apparent from just one image but it is totally apparent from watching the movie, neither group of roots grew worth a damn. Clearly, there is nothing helpful about germinating kernels on a jelly roll. Still, you can see from the picture that the doofus-grown roots are longer. Yes, they were longer at the start of the experiment, and that is useful. But why do none of them grow between towel and agar as they did in the first few experiments I ran?

I really don’t know. But here is another idea. To avoid wrinkles in the towel, I have been soaking it longer. This wets the towel thoroughly. I am guessing now, grasping at fallen leaves with a toothpick, but I wonder if the wetter towel grabs the agar more tenaciously?

I’d like to try handling the towel the way I did at the start of these experiments. But I was not paying close attention. I just sort of threw it over them. Rather than trying to recreate this, I am going to put a thin strip of towel, over the root between kernel and root tip, but not over the tip itself. The doofus roots are long enough, the strip should be wide enough to hold up the seedlings. And the root tip will be outside of the (putative) death grip of the towel. Let’s see what happens…