Transpiration and calcium accumulation in apricot fruit

The seasonal variation of transpiration rate and accumulation of calcium (Ca) in fruit of apricot (Prunus armeniaca L.) are presented. Midday transpiration rate (open system ADC-LCA4) was higher just after fruit-set peaking at about 0.5 mmol m-2 s-1; thereafter it declined and reached the lowest value three weeks later. In parallel, Ca was linearly accumulated within the early four weeks of fruit development reaching 80% of the final content. Afterwards it slowly increased and reached about 6 mg per fruit at harvest time. Results suggest that transpiration decline can be held to account for the early cessation of Ca import into the fruit. Opportunities for field manipulation to increase fruit Ca content are discussed.