- My duckweed cultures continued to grow nicely, especially the 15s clones, which have already filled the media's surface:
- I ran the starch assay with this sample.
I didn't have to run the calculations very far to find, to my crushing disappointment, that the purported percent starch of this sample was -0.18% LESS than the percent starch of the reagent blank.
...Physically, how is this possible?
It just does not make sense. After initial discussions with Dr. B we think it may be due to incomplete extraction in the ethanol-centrifugation step, but we'll have to further reexamine the procedure to find out.
Personally, I think the step where it says "discard supernatant" is somewhat sketchy - it could have been that residual amounts of starch that matter just enough for a small 56 mg sample as this were discarded in the supernatant.
If this were so, we would have to pellet the tubes longer and faster.
Another challenge we face in the near future is the fact that other than the 15s and 60s duckweed samples, we barely have enough duckweed fronds to grind up to meet the recommended 50 mg sample weight. For now, we're allowing the plants to grow indoors, where it's warmer. Later, I plan on putting them back into the greenhouse once spring starts getting into the swing of things.
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