ISHS Acta Horticulturae 410: II International Cherry Symposium
EFFECT OF CALCIUM TREATMENTS ON 'MONTMORENCY' SOUR CHERRY FRUIT QUALITY |
| Authors: | J. LaMar Anderson, W. F. Campbell |
| Abstract:
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. | |
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