Orchards management for reducing pomegranate aril browning disorder

Aril browning (AB) or aril paleness disorder in pomegranate fruit is a physiological injury that critically decreases fruit quality and marketability during recent years.
The main effects of the AB disorder are destruction in aril texture, oxidation of polyphenolic substances, discoloration in aril, and unpleasant taste of the fruit.
In this study, the effects of the overhead sunscreen, kaolin spraying, fruit thinning, supplementary irrigation, and fertilizer application on the AB disorder in pomegranate (P. granatum ‘Malas-e-Torsh-e-Saveh’) was investigated.
An experiment was carried out with eight treatments in a commercial pomegranate orchard, Saveh, Iran.
The treatments included: 1) 3% kaolin spraying on day 40 after full bloom (DAFB), 2) fruit thinning on 40 days (DAFB), 3) supplement irrigation on 80 days (DAFB), 4) combination of fruit thinning and kaolin spray, 5) supplementary irrigation combination with fruit thinning and kaolin spray, 6) control with conventional management, 7) animal manure application combination with foliar spray of the potassium sulfate and calcium nitrate, 8) overhead sunscreen combination with kaolin spray and supplementary irrigation during 2014 and 2015 growing seasons.
Quality attributes including fruit weight, dimension and volume, aril browning index, the frequency of the affected and non-affected fruits, juice (%), pH, electrical conductivity (EC), soluble solids concentration (SSC), titratable acidity (TA), and total anthocyanin of the fruit juice were measured.
The results showed that the kaolin spray did not have significant effects on the AB disorder, but the overhead sunscreen treatment combined with the supplementary irrigation and kaolin spray, effectively reduced the AB index by 24% and increased the abundance of non-affected fruit up to 96%. In the fruit thinning treatments, the AB index about 70%, and the frequency of the affected fruit increased significantly compared to the control.
Although supplementary irrigation positively ameliorates the AB disorder symptoms, the difference was not significant.
It seems that the AB disorder is produced by the interaction of the high air temperature, low relative air humidity, and low water quality.
Therefore, in the affected pomegranate orchard, the overhead sunscreen, increasing soil organic matter, irrigation with fewer intervals, and foliar potassium and calcium sprays during the growing season can improve the pomegranate fruit quality.

I International Conference and X National Horticultural Science Congress of Iran (IrHC2017)

M. Kavand, K. Arzani, M. Barzegar, M. Mirlatifi

anthocyanin, aril browning, ‘Malas-e-Torsh-e-Saveh’, supplementary irrigation, physiological disorder, overhead sunscreen, kaolin spray, fruit thinning

https://doi.org/10.17660/ActaHortic.2021.1315.74