Preventing cold storage disorders in nectarines

A storage experiment was aimed at preventing low temperature storage disorders in nectarine fruits, of cvs July Red and Autumn Grand. Fruit was either cooled immediately after harvest or kept at 20°C for 48 h, before transfer to controlled atmosphere (CA) conditions at 0°C. Combinations of 0, 10, 15 and 20% C02 with 8 and 16% 02 were assayed. The fruit was evaluated following cold storage, 31 days after harvest, and after four and eight days under ‘shelf conditions’ (ripening at 15-18 °C). Warming of the fruit at 20°C before cold storage prevented woolliness in the absence of elevated C02 levels but did not affect internal browning and increased reddish discoloration; further, it enhanced water loss and ripening, increasing fruit softening markedly. Conversely, high C02 delayed fruit ripening in CA storage, keeping the fruit firmer, and preventing the development of woolliness, internal browning and reddish discoloration during ripening, the best results being mostly obtained with 20% C02. 02 levels assayed did not show clear effects, but decreased 02 concentration in absence of high C02 showed some benefit in ‘July Red’. No deleterious effect of C02 concentrations even as high as 20% could be detected. Thus, even though high C02 in CA conditions showed promise for controlling disorders and preventing over-ripening, further work is needed on other cultivars, and lower 02 concentrations should be investigated before making a general recommendation.