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