A good protocol reads like a recipe, and each line has a reason. Here is how to read one and know what to check before you start.
1. Basal medium
Most protocols name a base such as Murashige and Skoog (MS), often at full or half strength, or a species-specific alternative such as WPM for woody plants. The base supplies mineral nutrients and vitamins.
2. Carbon source and gelling agent
Sucrose, commonly around 3 % (30 g/L), supplies energy. Agar, commonly 0.7 to 0.8 %, sets the medium. Liquid cultures omit the agar.
3. Plant growth regulators
These are the levers: a cytokinin such as BAP promotes shoot multiplication, and an auxin such as NAA or IBA promotes roots. The ratio between them matters more than either value alone.
4. pH and sterilisation
pH is adjusted before autoclaving, often to about 5.8. Media are typically sterilised at 121 °C and 15 psi, with hold time set by volume. Heat-sensitive additives are filter sterilised and added after cooling.
5. Culture environment
Temperature (commonly 25 ± 2 °C), photoperiod and light intensity are part of the protocol, not an afterthought.
6. Subculture interval and limits
Protocols give a transfer interval, often a few weeks, and sometimes a maximum number of subcultures to limit variation.
7. Records
Note the date, batch, medium lot and any contamination at every transfer. This is how you improve a protocol instead of repeating mistakes.
Understand the sequence first in the stages of tissue culture. Browse ready-made TC protocols or our propagation protocols page.