Feb 15th Another Error

In which I highlight a song by Nick Baskin about the same thing.

To illustrate how I feel about this past week’s events, check out this five minute clip. This is a scene from Window Full of Moths, written last year by my son Nick for his senior project at University. The clip is from an untended video recorder and the singers were not miked, but nevertheless it will give you the gist.

 

{Details and more clips, indeed the whole show, here}

Yes, another error, another brilliant waste of time. Not a spectacular piece of imbecility as was last week’s episode (read about it here), but no results all the same. This one was due to the plants misbehaving. Or more exactly, developing too slowly. Most of the seeds had germinated, but only just. The shoots were 1 cm or less, too small to harvest. The plants have done this to me before, once or twice. Supposedly I handle them the same way, every time. I checked for temperature excursions in the room but it seems stable. Admittedly it is around 22 to 23˚C, which is a bit cool for maize. Perhaps there is some kind of thresholdy thing where if the temperature dips nearer to 21˚C, then the development is more than linearly affected? Hmm….I should look at the temp trace more carefully.

But I can also attempt to build in a failsafe. Because the plants are often, or even usually, ready in four days, I have been starting them on Monday and experimenting (trying to experiment!) on Friday. Because I am loth to come in on Saturday (lazy graybeard that I am), when the plants are too young as they were this past Friday, I have to abort. Instead, I can start them on Friday and then check them on Tuesday. Yes, this means feeling up the plants in the dark. A bit awkward to be sure. But that way I can decide whether to do the experiment right then, or wait a day. An inconvenience but a lot better than a wasted week.

Naturally, this brings up the subject of reproducibility and correct controls. We should use the “same” material in a set of experiments and this would usually mean that when using four-day old plants, no fair substituting five-day old ones. But in fact, insisting on the same time is a temporal control—using time as a baseline for standardizing the material. But it is also possible to use a developmental control – that is, seedlings of the same size. This is what I am proposing to do.

Choosing the appropriate control is a common headache when evaluating treatments that affect development. I worked on maize seedlings subjected to water-deficit stress (in common terms – drought) and had to use both kinds of control: seedlings were compared after the same duration of stress and also when roots of each treatment had reached the same length, which happened at different times. But for the present case, just germinating seeds, the temporal and developmental controls should be identical. But clearly, something is affecting development. I could just always work with five-day old plants but if I did, then sometimes I’d have “older” plants. No solution is perfect. Compromise is essential.

I had also made a change in the growth conditions. It is possible that this change was responsible for the slower development, but I don’t think so because the same delay ruined a trial or two previously, without any such change. But as the change facilitates using four or five or even six day old plants, I will stick with it. Previously, I had been growing the seedlings in jelly rolls (discussed here). Using the jelly rolls is essential for working on roots because it lets them grow downwards and reasonably straight. But it has a problem for shoots because it speeds up when they hit the top of the box. Instead of jelly rolls, I am now putting moist paper flat on the bottom of the box. This is easier (always a plus) and gives the shoot another day or two before reaching the box top.

Now, there was a tiny victory last week. The silver glitter pen that I had at my flat turns out to be perfectly visible in infrared. This means that while setting up the experiment with my sniper scope, I can write down which treatment goes in which dish, and the order of imaging. Given my ailing memory, a crucial advance indeed.

 

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