| Using‘Qinying-1' sweet cherry as the material,the purpose of this study was to examine the effects of different concentrations of potassium sorbate and/or calcium chloride treatments in resisting Botrytis cinereaon sweet cherry.At room temperature(23 ±1?),using sterile water as the control,sprinkle the 20 g/L calcium before harvest,after treatment with 5 g/L potassium sorbate,and thecombinationof 5 g/L potassium and 20g/L calcium of sweet cherry.The effects of diameter of the spot,disease percentage and resistance-related enzyme activity by inoculated Botrytis cinereawere analyzed.Usingwater as the control,the ‘Van' sweet cherry was usedto examine the effect of different treatments on preservation.The treatments includedsprinkle the 20 g/L calcium before harvest,after treatment with 5 g/L potassium sorbate,and thecombinationof 5 g/L potassium and 20g/L calcium of sweet cherry.All fruits stored at 1 ± 0.5 ?with approximately 95% relative humidityand for 50 days.The main research results are as follows:1.Effect of calcium and potassium sorbate treatment on resistance to Botrytis cinerea in vitro.The calcium(Ca)treatment was used to inhibit the mycelia growth of Botrytiscinereaon PDA plate in concentration of 0,5,10,15,20 g/L,and the 20 g/L Ca treatment has a significant inhibitory effect on Botrytis cinerea.Meanwhile,the potassium sorbate(KS)could efficiently inhibit the mycelia growth of Botrytiscinereaon PDA plate in concentration of 0,1,3,5,7 g/L,and the inhibitory effect was enhanced by increasing concentrations of potassium sorbate.At the concentration of 5 g/L,the germination of spores and the growth of the bud tube were effectively inhibited,and the growth of mycelium was controlled.Under the electron microscopy,the Ca+KS process did not observe spore germination,indicating that the combination of 20 g/L Ca with 5 g/L KS had a significant inhibitory effect on Botrytis cinerea(P <0.05).2.Effects of sorbate,calcium and combined treatmentson induction of resistance to Botrytis cinereainsweet cherry.Compared to CK treatment,the treatments of pre-harvest 20g/L calcium,5g/L KS and the combined treatment couldsignificantlyinhibit the growth of gray mold and decrease the lesion diameter.The results showed that Ca+KS combined treatment of sweet cherry had the best induced effect on improving enzyme activity of polyphenol oxidase(PPO),peroxidase(POD),chitin(CHI)and ?-1,3-glucanase(GLU),reducing the degree of membrane lipid peroxidation and the content of malondialdehyde(MDA)in pulp.These results indicated thatcalcium and potassium stress could further induced the resistance to gray mold in sweet cherry.3.Preservation effect of sorbate and calcium treatment on sweet cherryIn the low temperature(1±0.5?)storage period,spraying the 20 g/L calcium before harvest(Ca),after treatment with 5 g/L potassium sorbate(KS),and the combination of 5 g/L potassium and 20g/L calcium(Ca+KS)of sweet cherryhad the fresh-keeping effects on preservation of sweet cherry.All treatments could effectively slow down the rate of conversion of titratable acid,reduce the respiration rate,delay the softening of sweet cherry fruit anddecrease the decay rate and weight loss rate.Meanwhile,the taste of fruit was preserved.The results indicated thatthe Ca+KS treatment has the best fresh-keeping effect,and there was a significant difference between the other treatments(P <0.05);The weight loss rate and decay rate of cherry was only 2.5% and 3.6%,while the control weight loss rate and decay rate of 8.58% and 13.9%.In addition,the activity of enzyme including PPO,POD,SOD,CAT,GLU and CHI were improved by the induced of Ca and KS treatments,especially the induction of chitinase and ?-1,3-glucanase activity maintained at a high level,thereby enhancing the fruit resistance to fungal infection and extending the shelf life of fruit.. |
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