Limitations associated with conductivity measurement for monitoring growth in plant tissue culture

The suitability of conductivity measurement for monitoring growth in plant cell culture has been tested using suspended cells and genetically-transformed hairy roots of Atropa belladonna, and aggregated cells of Solanum aviculare. Other researchers have proposed that a constant ratio exists between increase in cell concentration (Δx) and decrease in medium conductivity (ΔC). In all cases studied in this work, Δx/ΔC was not constant over a wide range of cell densities tested in batch culture. With cell suspensions, Δx/ΔC decreased continuously during the growth phase from 3.4 to 2.5 g cm l−1 mS−1. For the hairy roots, the ratio between Δx and ΔC varied by as much as 4-fold during growth. The relationship between conductivity and growth for S. aviculare aggregates was found to vary depending on inoculum density. No simple correlation between conductivity change and cell growth was apparent for the plant-cell systems studied.