Excellent firmness retention in ‘Golden Delicious’ apples was achieved in a “rapid CA” (rapid reduction of O2 by use of N2 flushing) storage procedure. Pretreatment of the fruit with high levels of CO2 prior to rapid CA had little or no effect on firmness. Higher flesh calcium content was beneficial in firmness retention when fruit was stored in air, in “slow CA” (O2 reduced by fruit respiration), or held in air for 10 days prior to rapid CA. Rapid CA provides an effective means to control softening in ‘Golden Delicious’ apples and to avoid injury caused by calcium and high CO2 treatments.

Red Delicious' apples were tested for response to irradiation, at levels (0 to I .O KGy) sufficient for quarantine treatment, delivered up to 10 months postharvest. Treatment regimes simulated marketing sequences including a 60 day holding period following removal from controlled atmosphere storage. Irradiated apples were softer and had less acid, but there was a retardation of the hydrolysis of starch. Irradiation effects were not accentuated with longer storage or during ripening. After I1 months of storage all the apples in this study were 6.7 ( N ) jirmer than the Washington State export standard. The quality of all treated fruit were acceptable for marketing.

Studies of low-O2 storage of ‘Delicious’ apple fruit (Malus domestica Borkh.) were conducted in Oregon (1981), Washington (1982), and British Columbia (1981 and 1982). A combination of 1% O2 with 1% CO2 was the most promising for control of storage scald and quality preservation of ‘Delicious’ apple fruit grown in Oregon. A combination of 1% O2 with <0.03% CO2 effectively reduced or eliminated the incidence of storage scald and preserved dessert quality of apples grown in Washington. Early-harvested apples from British Columbia developed a high incidence of storage scald after 7 months of storage in 1% O2 with 0.05% CO2. Apples harvested at commercial maturity, however, developed only slight or minimal storage scald symptom after 7 months of storage in 1 and 0.5% O2 with 0.05% CO2. A high incidence of low-O2 injury (i.e., ribbon-like, depressed skin browning) was found in fruit from Oregon stored for 9 months in 0.5% O2 (with or without CO2) and in 1.0% to 1.5% O2 with <0.03% CO2. No low-02 injury was found in fruit from Washington or British Columbia after low-O2 storage.

Tree cages were used to modify temperature around ‘Starking Delicious’ apple (Malus domestica Borkh.) trees and to establish 4 bloom dates: April 2, 15 and May 7, 22. Determination of soluble solids, acid, firmness and chlorophyll indicated that the time from bloom to maturity was longer for fruit from earlier than normal bloom. Fruit from delayed bloom accumulated less soluble solids than that from normal or earlier bloom dates. Ultimate fruit size decreased with each successive bloom. Fruit from the 2 early bloom dates apparently was harvested before the preclimacteric minimum. Fruit from delayed bloom was harvested after initiation of the climacteric. Loss of fruit firmness in storage increased with successive harvests. Storage scald and green fruit color were associated with warm night temperatures just before harvest rather than with length of growing season.

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