Abstract: The effect of pre-harvest CPPU (N-(2-chloro-4-pyridyl)-N’-phenylurea) treatment on cell ultrastructure of post-harvest kiwifruit during cold storage was studied. The treatment was conducted by dipping young fruits in CPPU solution at a concentration of 0, 10 or 20 mg/L at 28 days after flowering. The results showed that CPPU treatment accelerated the degradation of kiwifruit cell wall and internal structure in a concentration-dependent fashion. Treatment with 10 mg/L CPPU accelerated the degradation of kiwifruit starch granules and intercellular substances, and promoted cell wall deformation and the appearance of intercellular spaces, thus resulting in a rapid decrease of kiwifruit firmness. Treatment with 20 mg/L CPPU resulted in severe deformation of kiwifruit cell wall, the vacuolization of mitochondria and the disappearance of mitochondrial internal structure, thereby leading to the complete degradation of starch granules and loss of adhesion between cells. These findings suggested that CPPU treatment accelerated the degradation rate of kiwifruit cell wall, mitochondria and starch during storage and damaged the integrity of organelles and membrane system, causing decreased fruit firmness and storability decreased, shortened storage life and quality deterioration. Therefore, CPPU treatment is not recommended in kiwifruit production.

Key words: ‘Qinmei’ kiwifruit, firmness, N-(2-chloro-4-pyridyl)-N’-phenylurea (CPPU), ultrastructure