Influence of Chilling on Electrolyte Leakage and Internal Conductivity of Peach Fruits1

Abstract

Electrolyte leakage from tissue discs and internal conductivity of intact fruit of peach (Prunus persica (L.) Batsch) were determined during storage at 1°C and after transferring to 21°. Both methods produced similar results, however, the method used for measuring internal conductivity was rapid, nondestructive, and seemed to be more sensitive. Electrolyte leakage remained fairly constant while internal conductivity tended to decline during 5 weeks of chilling. Electrolyte leakage and internal conductivity increased when fruits were transferred to 21°. At 21° fruits which had been chilled for 2 weeks had enhanced leakage while conductivity was enhanced in fruits chilled for 1 and 2 weeks. In fruits transferred to 21° after 3 or more weeks of chilling, leakage and internal conductance declined and woolliness was concomitantly detected. The binding of free ions appears to be closely associated with woolliness in peaches.

In situ Measurements of Electrical Impedance and Resistance of Fruits: A Review

“…In general, impedance is used more often in the mea surement of hardiness than are exosmosis techniques, partly because of its relative ease, and because the tissue need not be sacrificed (11). Measurements of exosmosis in fruit are used most often as a criterion of membrane permeability or ion leakage (4,6,19,26,35), although there have been some in situ studies of electrical impedance or resistance in fruits.…”

“…Furmanski and Buescher (19) suggested that variations of in situ conductivity of peach tissue with chilling reflected changes in ion binding, but a sim pler interpretation of impedance or resistance measurements is that solute released from the cells into the inter cellular spaces with injury or senescence tends to decrease the resistance com ponent of impedance or resistance itself. Such an inter pretation would explain the correlation of ex osmosis readings with in situ biolelectric readings.…”

Physiological and Biochemical Responses of Plants to Chilling Stress

“…In some fruits, such as peaches, electrolyte leakage remains low and does not appear to be altered while the fruit are held at a chilling temperature but increases dramatically after the fruit are transferred to a ripening temperature (46). Some chilling-sensitive vegetables, such as bell peppers and eggplants, also do not exhibit any increase in electrolyte leakage at critical chilling temperatures (133).…”