DEGREENING OF 'MURCOTT' TANGOR WITH ETHEPHON TREATMENTS

Brazilian citrus production is located in tropical regions. Due to its climate conditions fruit can reach full internal maturity while the peel is still fully or partially green. This phenomenon makes the fruit unacceptable for consumers. ‘Murcott’ tangor (Citrus reticulata Blanco × Citrus sinensis Osbeck) shows problems of green peel near the junction of the pedicel, which thus affects fruit quality. The objective of the present study is to investigate the effect of an ethephon dip postharvest in degreening fruits of ‘Murcott’ tangor. Different concentrations of ethephon were used: 0, 500, 1000 and 2000 mg L^-1. After treatments by dipping in different solutions, fruit were stored at 15 or 25°C at 90% RH. Fruit were analyzed for color changes on the equatorial region of the peel and near the pedicel, soluble solids content (SSC), titrable acidity (TA), SSC/TA ratio; juice content in %, ascorbic acid content, ethylene production, respiration rate, total chlorophyll content and the activity of the chlorophyllase. It was observed that at both temperatures 15 and 25°C, there was an increase in color index, getting close to 2.0 that represents yellow color. Treated and untreated fruit with ethephon stored at 25°C had a greater increase in the index values of color than fruit stored at 15°C. It was observed that there was a reduction in the total chlorophyll content due to the increase of color index and activity of chlorophyllase. No differences were observed in the levels of SSC, TA and their ration. It was also observed that the production of ethylene and respiration rate were proportional to the concentration of applied ethephon and inversely decreases with lowering storage temperature from 25 to 15°C. Therefore it was concluded that ethephon treatments may have a potential commercial use for degreening fruit of ‘Murcott’ tangor.