Preparing for Sarawak – TZ testing for seed viability

Amongst the techniques we will be sharing with school students in Sarawak in our forthcoming trips (July and October) will be seed viability testing using TZ (2,3,5-Triphenyltetrazolium chloride).

Otto demonstrates the first stage – mixing orchid seed with 10% sucrose in a 1.5ml micro-tube. The tube then sits at room temperature for 24 hours. Everyone loves using a micropipette!

When the 24 hours are up it is time to remove the sucrose solution and replace it with 1% TZ solution  (centrifuges and vortex mixers are a great help with separating seeds from sucrose and then mixing with TZ) Microtubes are then put in a water bath at 40C for 24 hours for the TZ to react with respiration products and turn viable embryos red.

Great results under the dissecting microscope – red embryos = viable and so this seed that has been in our seed bank since Nov 2017 is 80-90% viable



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  1. Sarah Buckle says:

    Well done all, a very interesting write up to the build up to a very exciting trip for you all. Great to see your process, in sorting out the viability of seeds.