Spraying trees of nectarine (Prunus persica (L.) Batsch) with succinic acid-2,2-dimethylhydrazide (daminozide) or 2-(2,4,5-trichlorophenoxy) propionic acid (fenoprop; 2,4,5-TP) at initiation of pit hardening induced earlier fruit ripening by enhancing the rates of growth and color development. The climacteric peak occurred earlier in fruit from either treatment than in the controls. Whereas fenoprop enhanced CO2 evolution more than daminozide, daminozide stimulated postharvest ethylene production more than fenoprop. Treatment with both regulators did not have an additive effect in advancing the harvest date, in spite of a significant increase in color development and a somewhat increased rate of fruit softening. There was, however, an additive effect in stimulation of ethylene evolution.
SADH affected color enhancement of ‘Canino’ apricot (Prunus armeniaca L.) thereby increasing the percentage of fruit harvested during the first 2 harvests. The sprays at and after pit hardening had a greater effect on color than “after bloom” spray. Other parameters of ripening, however, were unaffected, or were even retarded, indicating the different effects of SADH on various species of stone fruits.
Astringency of ‘Triumph’ persimmon fruits (Diospyros kaki L.) was removed before, during or after storage at −1°C, by treatment with 90% CO2 at 17°C. The duration of treatment required for total removal of astringency depended on the time of treatment, the tannin content at the time of its application, and the length of the storage period and subsequent shelf-life.
Pre-storage treatment of fruits for 24 hours induced an accelerated rate of softening during 2−4 months storage at − 1°C. When CO2 was applied under the same conditions, 2 weeks prior to termination of storage, the rate of softening was reduced, in comparison with pre-storage gassing, but was still greater than that of untreated fruit. Post-storage gassed fruit remained firmer during shelf-life than that gassed earlier. Treatments of shorter durations before, during or after storage, did not, however, reduce the rate of fruit softening but accelerated it. At all times of application, longer durations in CO2 atmosphere slowed down the rate of fruit softening, in spite of the accelerated softening of CO2-treated fruits vis-a-vis untreated fruit. These apparently contradictory effects indicate that CO2 treatment of persimmons affects two different systems involved in fruit softening.
Control of woolly breakdown in ‘Elberta’ peaches was obtained by removal of the fruit to ambient room temperature (23–25°C) for 48 hours after 2 and 4 weeks' storage at 0°C. A 6 weeks' storage life was thus obtained. Warming the fruit after cold storage intervals shorter than 2 weeks was less effective after longer storage periods; the disorder was often enhanced by removal to room temperature.
A hypothesis to explain the development of woolly breakdown on the basis of these and previous data is discussed. It is suggested that further prolongation of storage could be obtained by repeated exposures to room temperature.
Pomegranate (Punica granatum L. ‘Wonderful’) fruit reached horticultural maturity for commercial harvest when the soluble solids content (SSC) attained a fairly constant level of 15%. The level of titratable acidity (TA) varied from one location to another and from one year to the next but also generally remained stable at the same time that the SSC reached 15%. After harvest, there was no further change in either SSC or TA at 20°C, but redness of the juice continued to increase in intensity up to and after harvest. The respiration pattern of the mature fruit was of the nonclimacteric type, with only traces of ethylene evolved on occasion. Ethylene treatment of the fruit caused a rapid transient rise in CO2 evolution but no changes in SSC, TA, and fruit or juice color. A pseudo-climacteric pattern of respiration was found in very young immature fruit. The respiration rate of dehisced arils paralleled that of the intact fruit, but there was no response to exogenous ethylene treatment. Ethylene evidently stimulated the CO2 output only of the fruit rind.
Controlled-atmosphere (CA) storage of astringent persimmon fruits (Diospyros kaki L.f. cv. Triumph) at −1° or 0°C enabled removal of astringency if CO2 content of storage atmosphere was 12% or more and O2 content was 3 to 5%. These gas combinations caused severe pulp injury and gave an alcoholic flavor to the fruit. At 3 to 9% CO2, astringency was reduced but not entirely removed and subsequent treatment of 12 hrs in 90% CO2 at 17°C was necessary to make the fruit edible. Storage life at −1°C was prolonged in 3% CO2 and 3 to 5% O2 due to less fruit softening and pulp discoloration. Higher CO2 concentration in the storage atmosphere accelerated softening, increased pulp injuries, and elevated respiration rates during shelf-life. Post-storage treatment in 90% CO2 at 17°C to remove astringency, slowed down the rate of fruit softening but accelerated the respiration rate, especially of CA-stored fruit.