April 18, 2012

Measuring growth rate by weight

Last week I wrote about tracking growth rate by measuring leaf length.  This week I started tracking harvest weight as well.  Here's what I do:

First I measure leaf length of ten leaves in a quadrant (same as before - this is still useful data to collect!).  Then I harvest all the leaves from the quadrant.  I don't cut at the soil level for two reasons: when you are harvesting salad greens you don't want the stem-y bits, you just want the leafy bits.  Also, if you leave the shoot apex (where new leaves come from) more leaves will grow and you'll be able to harvest a second crop from the same plants.

Bottom right quadrant harvested. 
 Next, all the leaves from the harvested quadrant get weighed.  Can you tell what green I am harvesting in these pictures?

Everything gets recorded in my lab notebook.  On the far left I identify the replicate, tray and quadrant I am measuring.  Then come the ten leaf lengths, and on the far right is the weight of all the leaves in that quadrant.  Eventually, I'll stick all the data into the computer and analyze it, but right now measuring, weighing and watering is enough to keep me busy.

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