Effect of an exogenous strigolactone GR24 on the antioxidant capacity and quality deterioration in postharvest sweet orange fruit stored at ambient temperature

Quality deterioration and senescence are the main causes of loss of fruit postharvest. Here, the effects of 200 mu mol L-1 strigolactone GR24 on the physicochemical characters, organoleptic quality, and antioxidant capacity of postharvest orange fruit were studied. GR24 increased fruit firmness (9.2%), citrus color index (22.34%), titratable acidity (11.7%), total soluble solid (13.13%), and soluble sugar content (8.17%) irrespective of the rates of weight loss (1.22%) and respiration (24.13%), indicating an improvement in organoleptic quality. GR24 also decreased the accumulation of hydrogen peroxide (30.08%) and malondialdehyde (27.59%), but increased the levels of antioxidants (ascorbate, glutathione, and total phenol) and enzyme activities (catalase, ascorbate peroxidase, and glutathione reductase), indicating an enhancement in antioxidant capacity. Moreover, GR24 delayed fruit senescence process by stimulating the boost of the antioxidant system during 0-63 days and delaying the quality deterioration at 77-91 days.