Vitis vinifera cell suspension cultures carried out in shake flasks were closely examined for biomass growth and cell division in relation to carbohydrate, NH,, NO,, PO,, and dissolved oxygen (DO) consumption. After inoculation, the oxygen uptake rate of the cultures measured on-line was observed to increase continuously to a maximum value of 3.8 mmol O-2 L(-1) h(-1) at day 7 when cell division ceased and dissolved oxygen reached its lowest level of 17% air saturation. During this first phase of growth, the specific oxygen uptake rate remained constant at similar to 0.6 mmol O-2 g(-1) dw h(-1) or similar to 2.2 mu mol O-2 (10(6) cells)(-1) h(-1), whereas dry biomass concentration increased exponentially from 1.5 to 6.0 g dw L(-1). Thereafter, dry biomass concentration increased linearly to similar to 14 g dw L(-1) at day 14 following nitrate and carbohydrate uptake. During this second phase of growth, the biomass wet-to-dry weight ratio was found to increase in an inverse relationship with the estimated osmotic pressure of the culture medium. This corresponded to inflection points in the dry and wet biomass concentration and packed cell volume curves. Furthermore, growth and nutrient uptake results suggest that extracellular ammonium or phosphate ion availability may limit cell division. These findings indicate that cell division and biomass production of plant cell cultures may not always be completely associated, which suggests important new avenues to improve their productivity.