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- Cold storage demand for Rocha pear ripening: A comparison between a shorter and a longer cold periodPublication . Dias, Cindy; Ribeiro, Tânia; Rodrigues, Ana Cristina; Ferrante, António; Vasconcelos, Marta W.; Pintado, Manuela'Rocha' pear is a cultivar that when harvested at the recommended maturity stage (physiological condition that allows resisting to prolong cold storage), requires chilling exposure after harvest, to induce an autonomously ripening appreciated by the consumer. Fruit were stored immediately after harvest, for 6 d (batch 1) or 26 d (batch 2), in normal cold atmosphere storage, to further our understanding of 'Rocha' pear ripening under different short cold storage durations. The ripening events were then monitored at 0, 3, 7, and 10 d of shelf-life at room temperature (± 20 °C) through physicochemical and biochemical changes, including firmness, soluble sugars, malic acid, esters profile, and ethylene metabolism (1-aminocyclopropane-1-carboxylic acid (ACC) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO)). We found that ripening behaviour upon rewarming from both cold storage periods was similar, with fruit ripening with a typical pattern of ethylene production and respiration rates concomitant with a higher ACO activity. Soluble sugar and esters emission were not influenced by cold storage duration, but interestingly butyl acetate levels were significantly higher on pear, which was cold stored for 26 d Our data provide more novel information about Rocha' pear's ripening physiology, indicating for the first time that approximately one week of chilling temperature is enough to promote ripening rate processes. Such knowledge could be an asset to the efficient management of 'Rocha' pear storage.
- Preliminary results on the effect of 1-naphthaleneacetic acid on restoring ‘Rocha’ pear ripening treated with 1-MCPPublication . Dias, C.; Rodrigues, A.C.; Vasconcelos, M.W.; Ferrante, A.; Pintado, M.Loss of ripening capacity is still a major problem associated with the use of 1-methylcyclopropene (1-MCP), despite its benefit in preserving climacteric fruit under long-term cold storage, specially, in controlled atmosphere. Several strategies have been tested to overcome this problem, namely the use of phytohormones (e.g., ethylene). In this study, ‘Rocha’ pear treated with 1-MCP was after storage exposed to a synthetic phytohormone, the auxin 1-naphthaleneacetic acid (1-NAA) at 2 mM, for 2 h. Before treatment, as well as 3, 6 and 24 h after treatment, the primary impact of 1-NAA on the expression of genes encoding ethylene receptor (PcETR2) and ethylene biosynthesis enzyme (PcACS4) was determined. The restoration of ripening capacity was assessed across shelf-life by measuring ethylene production and 1-aminocyclopropane-1-carboxyl acid oxidase (ACO) activity. Herein, the expression of PcACS4 significantly increased in pears treated with 1-NAA compared to pear treated only with 1-MCP. Additionally, the expression of PcETR2 was enhanced, revealing the potential of the 1-NAA treatment in inducing the production of new ethylene receptors. Time course physicochemical analysis revealed that fruit ripening was promoted by 1-NAA treatment, as judged by the higher ethylene production (ca. 50%) and ACO activity (ca. 15%) compared to treated only with 1-MCP. The application of the auxin indicated its potential in reactivating the ripening of ‘Rocha’ pear under the effect of 1-MCP.