How to determine seed viability by red tetrazolium salt method?

Red tetrazolium method: also known as TTC method, is a better method to determine seed viability in the world. Its principle is that the oxidized colorless triphenyltetrazole chloride accepts the hydrogen produced by dehydrogenase during the respiration of living seeds and becomes a red reducing substance. The dehydrogenase activity of viable seeds is often high, tetrazole is reduced to red by hydrogen ions, and dead tissues are not colored, so the viability of seeds can be judged according to the dyeing position and dyeing depth.

Red tetrazole is a white or yellowish toxic powder, which should be stored at low temperature and away from light. Prepare 0. 1% ~ 1% solution with distilled water, and adjust the pH to neutrality with dilute alkali (for example, it is better to adjust the pH to 6.8 ~ 7.2 with 0.05 ~ 0. 1 mol/L phosphate buffer with pH7.5). Put the brown bottle in the refrigerator for use.

Soak the tested seeds in 16 ~ 24 hours, then carefully cut the seeds into two pieces along the seed ridge, put them in a beaker or a Petri dish with the cut face down, drop the tetrazole solution into the profile, put them in an incubator at 25 ~ 30℃ for 8 ~ 24 hours, then take them out and wash them, and observe the dyeing reaction. The higher the temperature, the faster the dyeing. If placed at room temperature, it needs to be protected from light, because tetrazole solution is sensitive to light. Vigorous seed embryos are dyed red, while inactive seeds are not dyed or have only light red spots.