EFFECT OF CALCIUM TREATMENTS ON ‘MONTMORENCY’ SOUR CHERRY FRUIT QUALITY

Senescence and moisture loss, which are crucial factors in post-harvest softening of cherries with subsequent loss of cellular turgidity and fruit quality, may be ameliorated by calcium (Ca²⁺) ions.
During the 1988–1991 harvest seasons, 1.4 kg of calcium chloride (CaCl₂) in the holding tanks resulted in firmer fruit of ‘Montmorency’ sour cherry with a higher character grade following pitting.
In 1992, cherries from trees that had pre-harvest foliar applications of an amino acid calcium chelate (calcium metalosate, Albion Laboratories Inc.) also had higher character grade ratings.
To ascertain the role of Ca²⁺ in enhanced fruit quality, fruit pulp was homogenized and a plasma membrane (PM) vesicle fraction isolated from harvested cherries held in cold water, 2% CaCl₂ solution or comparable rates of amino acid calcium chelate.
Electron micrographs of the vesicle fraction consisted of 85–90% sealed PM vesicles.
Protein activity of vesicles from Ca²⁺ treated fruit was as much as 4 times higher than from untreated fruit.
Uptake of Ca²⁺ by PM vesicles was ATP-dependent.
Incubation of the vesicles with the calcium ionophore A123187 caused vesicle membrane lysis to occur, releasing the Ca²⁺ ion.
Orthovanadate appeared to be a non-competitive inhibitor of PM ATPase activity and H⁺-pumping, indicating that the fractions were free of non-plasma membrane ATPases.
The sealed PM vesicle system appears to be suitable for evaluating the role that Ca²⁺ plays in maintaining cherry fruit quality.

II International Cherry Symposium

J. LaMar Anderson, W. F. Campbell

https://doi.org/10.17660/ActaHortic.1996.410.53