I'd say 1000ppm was way too high a dose - I use 250ppm for seeds,
and have observed this 'overdose' effect on Proboscidea parviflora
when I was first playing with GA3 and didn't know about the dosage
(well, OK, I mostly just wanted to see what would happen :) I
probably had a concentration several times yours. They just burst
open in a mass of cells, and then died. I can't comment on how
they compared to normally germinating ones, as I'm still waiting
for a more sensibly treated batch to sprout, but I believe excess
GA3 will at least inhibit rooting.
I know that some tissue cultured plants require exogenous GA3 for
satisfactory micropropagation (Potato, Dahlia, etc.) but the dosage
used is in the order of 0.1mg/L - does anyone know if any CPs (in
tissue culture,) fall into this category?
And if testament to the power of GA3 was needed, I had a Mimosa
pudica germinate the other day in 2 1/2 days after 24hrs in 250ppm
GA3!! - not bad for last year's seed!
Happy growing,
Peter