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Effect of modified atmosphere on rotting of stored Kinnow mandarins

Amarjit Singh*, Rajinder Singh*, J.S. Dhiman**

**Department of Processing and Agricultural Structures
**Department of Vegetable Crops, Landscaping and Floriculture
**Punjab Agricultural University
**Ludhiana - 141 004, Punjab, India

The storage behaviour of Kinnow mandarins (Citrus reticulata Blanco) with particular reference to their fungal rotting was studied under different conditions of storage. The relative efficacy of three storage techniques, viz. cooling chamber (CC), room temperature storage (RTS), and commercial cold storage (CCS) was compared. The effect of a raised CO2 level (2, 3, 4 and 5%) on the rooting process was studied both at room temperature (8-30°C, Avg. 21°C) as well as at a low temperature (5°C).

Stalk end rot (SER) was more common and severe than surface rot (SR) of the stored fruits. In the beginning the rotting was mainly due to Alternaria citri and A. alternata, whereas that appearing subsequently was due to species of Diploida and Phomopsis. The SR on the fruits supported profuse growth and sporulation of Penicillium digitatum and Aspergillus flavus. The fruits stored at room temperature suffered more rotting than those stored in CC and CCS. In RTS disease was expressed after 20 d, whereas its appearance was delayed by 40 d under cold storage.

Although the raised CO2 was effective in suppressing the intensity of fungal rotting both at 5°C and at room temperature, the effect was more pronounced at 5°C. Irrespective of the CO2 levels, disease appeared after 30 d at room temperature, while at 5°C it was delayed by 50, 70, 30, and 60 d in fruits stored at 2, 3, 4, and 5% CO2 levels, respectively. Hence, Kinnow mandarins can be kept disease free by being storage in a structure having a combined facility of low temperature and a regulated level of CO2.

Singh A., Singh R., Dhiman J.S., 1992. Effect of modified atmosphere on rotting of stored Kinnow mandarins. Folia Horticulturae IV/2: 43-57.