Postharvest Quality of 'Bing' Cherries Following Preharvest Treatment with Hydrogen Cyanamide, Calcium Ammonium Nitrate, or Gibberellic Acid

Abstract

During three consecutive years, 'Bing' sweet cherry ( Prunus avium L.) trees were treated during dormancy with the dormancy-manipulating compounds, CH 2 N 2 or CaNH 4 NO 3 , or were treated with the plant growth regulator GA 3 at straw color development. Fruit of a range of maturities, based on skin color, were evaluated for quality following harvest and simulated transit and market storage conditions. At comparable maturities, CH 2 N 2 and GA 3 fruit were of similar firmness and were consistently firmer than CaNH 4 NO 3 -treated and untreated fruit across years, storage regimes, and maturities. CaNH 4 NO 3 and untreated fruit were of similar firmness. CH 2 N 2 -treated cherries were larger than fruit of other treatments, but only marginally with respect to variation in fruit size between years. Contraction of fruit diameter occurred after 3 days storage, but ceased thereafter up to 11 days storage. Soluble solids and titratable acidity varied between years, storage regimes, and maturities. Strong interactions of treatment and year concealed possible treatment effects on these indices. GA 3 fruit contained fewer surface pits in one year while CH 2 N 2 fruit suffered less shrivel in another. The earlier harvest date for CH 2 N 2 fruit often avoided higher field temperatures and the resulting promotion of postharvest shrivel. Pitting and shrivel were more prevalent in stored fruit. Brown stem discoloration developed in storage, occurring most frequently in mature fruit, although methyl bromide-fumigated fruit were particularly susceptible. This disorder was more common in GA 3 fruit during years of high incidence. Chemical names used: gibberellic acid (GA 3 ); calcium ammonium nitrate (CaNH 4 NO 3 ); hydrogen cyanamide (CH 2 N 2 ).