Temperature, length of cold storage and maturity influence the ripening rate of ethylene-preconditioned kiwifruit

Abstract

Abstract The effect of temperature, length of cold storage and maturity on the ripening of ethylene-preconditioned (100 μl l −1 for 12 or 24 h) kiwifruit was investigated. Low (0 o C) temperatures at any point prior to, during or after ethylene preconditioning significantly delayed softening and soluble solids concentration (SSC) accumulation compared to higher temperatures (i.e. 20 o C). Freshly-harvested kiwifruit responded to ethylene-preconditioning (100 μl l −1 at 0°C for 24 h) by softening faster than control fruit even if harvested 5 weeks after commercial maturity. In contrast, kiwifruit harvested at commercial maturity and stored at 0°C softened faster than the control only if preconditioned with ethylene during the first 2 weeks of storage. Kiwifruit had high respiration rates 1 day after being transferred from 0 to 20°C, but respiration dropped to near base-line levels by day 2. Fruit stored at 0°C always respired faster upon transfer to 20°C than did freshly-harvested fruit and preconditioning with ethylene increased the initial rate of respiration of freshly-harvested fruit but had less of an effect on stored fruit. Ethylene preconditioning did not significantly hasten the climacteric rise in respiration or ethylene production of either freshly-harvested or stored kiwifruit. The climacteric rise of individual kiwifruit began only after fruit softened to ≤7 N.