Effect of heat shock and potassium sorbate treatments on gray mold and postharvest quality of ‘XuXiang’ kiwifruit

•The growth of Botrytis cinerea in vitro is delayed by heat shock (HT) and potassium sorbate (PS).•HT and PS treatment maintained the activities of PAL, PPO, POD, CHI and GLU in kiwifruits.•HT+PS treatment significantly enhanced defense responses in vivo, thus controlling postharvest decay of kiwifruit. We determined whether heat and chemical treatments could reduce the decay of kiwifruit caused by Botrytis cinerea during postharvest storage. Kiwifruits were treated with 5 g/L (w/v) potassium sorbate (PS), with a 48 °C hot water treatment (HT), and with a combined treatment (HT + PS). Mycelial growth of B. cinerea and the postharvest quality of ‘XuXiang’ kiwifruits were evaluated. HT + PS significantly inhibited mycelial growth, germ tube growth, and spore germination of B. cinerea. This treatment also reduced the incidence of gray mold in kiwifruit postharvest, and enhanced activities of defense-related enzymes in kiwifruit tissues. Compared with the control, all treatments resulted in lower malondialdehyde (MDA) contents and higher total phenolic contents in kiwifruits. HT + PS also increased the activities of chitinase and β-1,3-glucanase and the transcript levels of their encoding genes. HT + PS can improve kiwifruit quality and reduce decay during postharvest storage.