Plums of cultivar Wegierka Zwykla (Prunus domestica L.) were stored during ten weeks in conditions of controlled atmosphere (CA) at increasing concentrations of CO2. The controlled conditions had a pronounced favourable influence on fruit firmness. The possible storage period was lengthend with higher concentrations of CO2 in the chamber: with 3% CO2+3% O2 by two weeks, with 5% CO2+3% O2 by 4 weeks, and in the combination of 15% CO2+3% O2 by 8 weeks as compared with fruit from a cold store (CS). The latter lost over 50% of the initial firmness as soon as after two weeks of storage. There were determined high positive coefficients of correlation of fruit firmness with soluble sugars and organic acids, and high negative coefficients with weight losses and hydropectins. The coefficients show that the firmness of plums is closely associated with turgor in their flesh.
