Physiological profiling on ‘Rosy Glow’ apples harvested at different maturities, with special reference to internal browning development potential

Improved colour development potential and high yield characteristics of ‘Rosy Glow’ apples led to an increase of propagation and planting thereof. No ground work (physiological profiling or storage protocols) had been done for this ‘Cripps Pink’ strain.

Objective 1: To establish the effect of harvest maturity and storage duration on the overall quality of ‘Rosy Glow’ apples stored for 2, 4 and 6 months RA (relative atmosphere) at -0.5 °C and 1.0 °C with special reference to internal browning development (2014/ 2015)

Objective 2: To establish the effect of box liners and 1-MCP on optimum maturity ‘Rosy Glow’ apples under CA (controlled atmosphere) cold storage conditions and the effect of cooling rate under RA cold storage conditions (2016)

Objective 1: Fruit were harvested at three different harvest maturities (pre-optimum, optimum and post-optimum) and stored for 2, 4 and 6 months under RA conditions at -0.5 °C and 1.0 °C, followed by a 7 day shelf life period at 20 °C.

Objective 2: ‘Rosy Glow’ apples were harvested at optimum maturity where after they were split into either a 1-MCP/ liner component CA trial or a cooling component RA trial. The former were either subjected/ not subjected to 1-MCP stored for 3 and 4 months CA at 1.0 °C and then packed with/ without liners. The latter was either step or rapid cooled and stored for 2.5 months RA at 1.0°C. All fruit were evaluated after 6 weeks “packed” RA at 1.0 °C and after 7 days shelf life at 20 °C.

2014: From the data it was evident that ‘Rosy Glow’ apples are prone to superficial scald incidence when harvested at a pre-optimum maturity and cold stored under RA conditions. Low incidence of internal browning occurred.

2015: Again data indicated that pre-optimum harvested fruit stored under RA conditions exhibited the highest incidence of superficial scald. Low severity of internal browning was exhibited only after extended RA storage (6 months) cold stored at -0.5 °C.

2016: It could also have been a low incidence year, but after one season of testing, CA storage seemed to alleviate the occurrence of superficial scald. Low levels occurred in the RA component of the trial. The addition of 1-MCP resulted in the expected firmness and colour benefit. The addition of a box liner alleviated greasiness and to an extent colour break from occurring and 1-MCP alone was sufficient to control greasiness. Although it increased stem and calyx end decay incidence, this dissipated during the shelf life period.

Data collected over three years suggest that ‘Rosy Glow’ apples may not be as susceptible to internal browning as in ‘Cripps’ Pink’ apples when harvested at optimum maturity. CA storage and box liners are advised. Unacceptable levels of superficial and peduncular scald render the fruit unsuitable for extended RA storage. The addition of 1-MCP should be considered if fruit are to be stored for an extended period, but this may lead to an increase in internal browning. Further studies should include this to assess this risk.