Control Effect Of Ozone Treatment On Major Infectious Diseases Of Kiwifruit In Cold Storage

In order to investigate the control effect of ozone on postharvest diseases of kiwifruit,the pathogens isolated from kiwifruit during cold storage were isolated and identificated.The effects of ozone with different concentration on conidia germination rate,sporulation,mycelial growth and colony expansion were studied in vitro The pathogenicity and related enzyme activities of major infectious pathogens of kiwifruit were studied in vivo.The incidence and storage quality of kiwifruit were determined by ozone treatment.The results of the study as follows:The main pathogens of kiwifruit(Qinmei and Hayward)were Penicillium sp.and Botrytis cinerea,and rotten parts mainly concentrated in the pedicel and fruit peel,which are gray,white,green and black mold layer grows,the major pathogens were infected through wound;The incidence of kiwifruit was higher at high temperature and humidity,and its incidence increased with the extension of storage time.Ozone treatment significantly inhibited the germination rate,mycelial growth and spore production of Penicillium sp.and Botrytis cinerea,and the higher the concentration of ozone,the longer the treatment time,the more obvious bacteriostatic effect.170mg/m~3 or more ozone treatment significantly inhibited the activity of Penicillium sp.and Botrytis cinerea.The Penicillium sp.and Botrytis cinerea With 250mg/m~3 ozone treatment 60min showed best effect.The germination rate of spores decreased by 30.2%,22.2%,compared with the control group,the inhibition rate of sporulation were 70.98%,83.12%.The mycelial dry weight was only about 18.9%and 8.8%compared with the control,and the colony diameter was 23.1%and 36.7%.Ozone treatment not only inhibit the pathogenicity of Penicillium sp.and Botrytis cinerea,and can also delay the expansion of lesion,improve the activity of enzyme related to disease of kiwifruit.With 170mg/m~3 ozone treatment 60min,the incidence rate of Penicillium sp.and Botrytis cinerea were decreased by 57.6%and 54.1%,respectively.The lesion diameter were 44.8%and 46%compared with the control.The POD,PPO,PAL,β-1,3glucanase and chitinase activity were significant increased.Through the study of the quality changes of Qinmei and Hayward kiwifruit,it was found that ozone effectively delayed the decrease of titratable acid and VC,inhibit the rise of SSC,reduce decay rate,chilling injure rate and inhibit the accumulation of MDA,prolong the storage period and keep the quality of kiwifruit.The best storage conditions for Qinmei and Hayward were 170 mg/m~3of ozone concentration,daily treatment 1h,continuous for 7 days,storage temperature 0℃,RH90~95%.