Potassium nitrate is an inorganic compound with the chemical formula KNO₃, appearing as a white, crystalline, water-soluble solid. In plant tissue culture applications, potassium nitrate is used as a source of essential macronutrients, providing potassium (K⁺) and nitrate nitrogen (NO₃⁻) required for cell growth, division, and metabolic activities.

In tissue culture media, potassium nitrate contributes to osmotic balance, enzyme activation, and protein synthesis, supporting healthy callus formation, shoot proliferation, and root development. It is commonly incorporated into basal culture media formulations as a controlled nutrient source under sterile laboratory conditions.