# Average / Rate - help pleaze (Oct/31/2007 )

Hi

i'm getting so confused about calculating the rate of growth of seedlings during 10 days

how do u calculate the rate of growth (length of seedlings)?

i added the lengths during the 10 days and divided the sum by 10 !!

thanx in advance

well it depends

is the growth geometrical? (then you did it right)

or is it exponential?

in that case try this one:

growth after ten days = growth at start times growth rate to the power of days

Well, you can take several time-points instead of only one.

Then you just have to plot them in excel and calculate the growth rate from there.

The thing is that you might not be able to classify general growth neither as geometrical nor exponencial. Some growth stages may be the first and others the last. It depends a lot on the plant you're working with, growth conditions, etc.

I'd say take more time-points to better characterize the growth curve.

Or sigmoidal growth rate!

I think it is best if you measured your seedlings every day for 10 days. Or if adventures, stick a camera and place a ruler by side of said seedling and have timelapse to see the growth rate! I understand webcams are going rather cheaply these days. Have the cam take a picture every hour