Effects of High Humidity Conditions on Coloring Disorder and Quality of Fruit in ‘Irwin’ Mango

Abstract

Under greenhouse cultivation of ‘Irwin’ mango, coloring disorder tentatively called red bruise and mottled skin occurs. The red bruise is a symptom of red spots on the fruit skin, and mottled skin is a symptom of red and orange patches on the fruit skin. We investigated the effects of high humidity conditions on coloring disorder and fruit quality in ‘Irwin’ mango. We also investigated the relation between days after full bloom stage (DAFBS) and coloring disorder. The duration of humidity treatment was 21 days from 15 May to 4 June, 2019. During this duration, the relative humidity in the humidification treatment (HT) maintained higher than that in the dehumidification treatment (dHT), and the average value of the vapor pressure deficit in day time was 1.72 kPa in the HT and 10.36 kPa in the dHT. The degree of red bruise, mottled skin and resin fruit was higher in the HT than in the dHT. The degree of red bruise and mottled skin was higher in 70-90 DAFBS than in 80-100 DAFBS. Compared to the dHT, the a* value in the equator and stylar end of fruit was lower in the HT. The sugar content in the HT was lower than that in the dHT by more than 2 ^oBrix. In conclusion, it was clarified that high humidity contributes to the occurring of coloring disorder, and that the sugar content also decreases in ‘Irwin’ mango.