Residue analysis and effect of preharvest forchlorfenuron (CPPU) application on quality formation of kiwifruit

Forchlorfenuron (CPPU) is widely used as a growth regulator in kiwifruit production to improve fruit yield. However, little is known about the dissipation profile of CPPU and the effect of pre-harvest CPPU treatment on fruit aroma formation during storage. Here, high (0.02 g L −1 ) and low (0.005 g L −1 ) dosages of CPPU were applied to ‘Biyu’ kiwifruit at twenty days after anthesis (DAA). The results revealed that 4-OH-CPPU was the main metabolite from CPPU and the 75 d after treatment is a key period for the conversion of CPPU into 4-OH-CPPU. Pre-harvest CPPU treatment reduced fruit hardness, respiratory rate, fatty acids, fatty-acid derived volatiles (FA-VOCs) and activities of ROS scavenging enzymes such as SOD, POD and CAT, but evidently increased the levels of malondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), total soluble solids (TSS), some sugars and amino acids during storage, especially in fruit under high-dosage CPPU treatment. Therefore, we concluded that pre-harvest CPPU treatment might inhibit fatty acid biosynthesis, reduce membrane integrity and further decrease fruit storage ability and aroma quality, and therefore pre-harvest application of high-dose CPPU on kiwifruit is not recommended. These results would help to clarify the action mechanism of preharvest CPPU treatment on aroma formation and provide reference for the rational application of CPPU on kiwifruit. • CPPU was mainly transformed into 4-CPPU-OH within 75 days after application. • Preharvest CPPU treatment increased sugars but decreased fruit storage ability. • Preharvest CPPU treatment decreased FA-VOCs but increased terpenoids. • Lower fatty acid level in CPPU treated kiwifruits resulted in lower levels of FA-VOCs.