delay between a 38 degree C pretreatment and damaging high and low temperature treatments influences pretreatment efficacy in 'Hass' avocados

• Published in: Postharvest biology and technology 2004, Vol.34 (2), p.143-153
• Main Authors: Woolf, A.B, Bowen, J.H, Ball, S, Durand, S, Laidlaw, W.G, Ferguson, I.B
• Format: Article
• Language: English
• Subjects: air; avocados; chilling injury; cooling; decline; deterioration; dose response; heat; heat shock proteins; heat tolerance; high temperature treatment; hot water treatment; pericarp; pretreatment; RNA; temperature; water
• ISSN: 0925-5214; 1873-2356

Pretreatments at moderate temperatures applied immediately prior to the high or low temperature treatments can reduce skin damage to avocados. These temperature tolerance-inducing pretreatments have generally been applied immediately prior to the high or low temperature. We examined whether a delay between the pretreatment and potentially damaging high and low temperatures may cause a loss in the induced tolerance. A hot air pretreatment (38 °C for 6 h) applied prior to storage at 0 °C for 3 weeks with intervening delays of 1-4 days at 20 °C, showed a large reduction in chilling injury as a result of the pretreatment but that this was progressively lost with increasing delay to storage. Hot water pretreatments (38 °C for 0, 5, 20 and 60 min) increasingly reduced chilling damage at 0 °C, and heat damage from a hot water treatment (HWT) at 50 °C/10 min. With delays of up to 3-24 h prior to the HWT, heat damage was reduced for the 5 and 20 min pretreatments. However, delays up to 5 days between pretreatment and HWT, loss of heat tolerance was observed. For delays of between 1 and 5 days there was a clear loss of chilling tolerance which was more rapid than the increase in chilling injury in control treatments for the same delays. However, the effect of delays