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

The effect of temperature, length of cold storage and maturity on the ripen ing of ethylene-preconditioned (100 mu l l(-1) for 12 or 24 h) kiwifruit wa s investigated. Low (0 degrees C) temperatures at any point prior to, durin g or after ethylene preconditioning significantly delayed softening and sol uble solids concentration (SSC) accumulation compared to higher temperature s (i.e. 20 degrees C). Freshly-harvested kiwifruit responded to ethylene-pr econditioning (100 mu l l(-1) at 0 degrees 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 degree s C softened faster than the control only if preconditioned with ethylene d uring the first 2 weeks of storage. Kiwifruit had high respiration rates 1 day after being transferred from 0 to 20 degrees C, but respiration dropped to near base-line levels by day 2. Fruit stored at 0 degrees C always resp ired faster upon transfer to 20 degrees 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. Ethy lene preconditioning did not significantly hasten the climacteric rise in r espiration or ethylene production of either freshly-harvested or stored kiw ifruit. The climacteric rise of individual kiwifruit began only after fruit softened to less than or equal to 7 N. (C) 1999 Elsevier Science B.V. All rights reserved.