Effect Of Ozone On Controlling Gray Mold On 'Red Globe' Grapes

Botrytis cinerea was treated with ozone gas at different concentrations(0,30,60,90 ?L/L)for different times(5,10,15 min),then cultured at 24? for 5 d.The diameter of mycelium,formation of Botrytis cinereaspores and plasma membrane integrity was analyzed to study the inhibition effect of ozone on the Botrytis cinerea.Postharvest ‘Red Globe' grapes was inoculated with Botrytis cinerea and exposed to these four different concentrations of ozone for 15 min,then stored at room temperature for 7 d.The incidence,lesion size and the activity of severalenzyme were measured to study the inhibition effect of ozone on controlling gray mold on the postharvest ‘Red Globe' grapes.After that,three treatment was set which wereozone gas fumigating treatment at the concentration of 90 ?L/L for 15 min,interval of 4 h treated with ozone gas at the concentration of 90 ?L/L for 15 min and SO2 treatment,then stored at room temperature for 7d.The incidence,lesion size and the activity of severalresistant substance were measured to study the inhibition effect of different ways of ozone treatment and SO2 treatment on controlling gray mold on the postharvest ‘Red Globe' grapes.The results are as follows:1.Compared with the control group,the myceliumgrowth of Botrytis cinerea was inhibited by ozone but the effect decreased constantly.Ozone can damage the integrity of plasma membrane of Botrytis cinerea which were responsible for the reduction of conidia germination.With the treatment time and concentration increasing,the effect was improved.The density of mycelial growth of Botrytis cinerea was decreased and gully was observed at the surface of mycelial under scanning electron microscopeafter treated with ozone at the concentration of 90 ?L/L for 15 min.What's more,the germination of spores was delayed by ozone for 1 h,and the growth of germ tube was inhibited after 12 h.2.The growth of Botrytis cinerea at the grapes was strongly inhibited by ozone but only at concentration of 60 and 90 ?L/L.Meanwhile,ozone can inhibit the accumulation of the malondialdehyde(MDA)content and maintain the higher level of antioxidant enzyme(PPO,POD)and resistance protein(CHI,GLU)activities.The 90 ?L/L concentration of ozone treatment group has the best effect.3.Compared with the control group,the growth of Botrytis cinerea on the surface of grape fruit and the incidence of fruit was inhibited by different ozone treatment and SO2 treatment.However,the inhibition effect of ozone interval treatment on Botrytis cinerea was not as good as that of only treated withozone for once treatment group after 4 d.SO2 treatment has the best effect on the inhibition of the growth of Botrytis cinerea.Compared with the control and SO2 fumigation treatment,ozone treatment can maintain the higher level of antioxidant enzyme(PPO,POD)and resistance protein(CHI,GLU)activities,promoting the synthesis of resveratrol in pericarp.Although the effect of ozone treatment on the mycelial growth of Botrytis cinerea was not as good as that of SO2,ozone had the advantages of health,non-toxic and pollution-free,so it can be used as an effective preservative for green organic grapes.