S. Siddiqui et F. Bangerth, DIFFERENTIAL EFFECT OF CALCIUM AND STRONTIUM ON FLESH FIRMNESS AND PROPERTIES OF CELL-WALLS IN APPLES, Journal of Horticultural Science, 70(6), 1995, pp. 949-953
Apples of cv. Golden Delicious, about one and a half months after frui
t set, were sprayed eight times at weekly intervals with 40 mM solutio
n of CaCl2 and SrCl2. The firmness of the fruits, beta-D-galactosidase
activity, contents of free and covalently bound pectins, and hemicell
uloses were not significantly different under various treatments at th
e time of harvest. However, after 20 d of storage, the flesh firmness,
contents of total, ionically and covalently bound pectins with respec
t to control were higher in CaCl2 and lower in SrCl2 treated fruits. T
he activity of beta-D-galactosidase was decreased by CaCl2 but not by
SrCl2 treatment. The total pectin content of the walls with respect to
control was higher in CaCl2 and lower in SrCl2 treated apples. It was
observed that preharvest application of CaCl2 may not always lead to
firmer fruits at the time of harvest but may result in a better retent
ion of firmness during storage. It was further indicated that the effe
ct of calcium on flesh firmness and cell wall properties was not simpl
y electrostatic or of a bivalent cation but through some specific effe
ct.