Growth index of callus culture is calculated using:
Growth index measures proliferative performance of callus cultures quantitatively allowing comparison across media treatments hormone combinations and genotypes. Most accurate method utilizes change in dry weight rather than fresh weight or visual scoring because fresh weight is confounded by variable water content due to hyperhydricity, extracellular polysaccharide secretion, and vacuolar water uptake that fluctuates with osmolarity of medium. Dry weight determination involves harvesting callus, washing to remove agar, oven drying at 60 to 80 degrees Celsius to constant mass eliminating moist
Ref: Bhojwani & Razdan 1996 growth indices; Plant Cell Culture protocols dry weight method.
