| Eucalyptus is one of the important plant species in southern China.In recent years,with the growing area of planting,Eucalyptus disease caused by the loss is also increasing,seriously restricting economic development of our country.Eucalyptus bacterial wilt,known as the "cancer" on Eucalyptus,is an important disease that occurs on Eucalyptus.Its occurrence area is large,wide range of hazards,and in the event of no specific strong effects of medicines,the economy caused a very serious damage.At present,China's Eucalyptus planting the main demand is wood,but its twigs and leaves do not attach importance.Plant volatile oil is an important plant resource,Eucalyptus leaves and branches contain a lot of volatile oil resources,and most of the broad-spectrum antibacterial activity.In this paper,the volatile oil of the common Eucalyptus species in Guangdong were extracted from the leaves and the branches,and the composition and content of the components were analyzed by GC-MS.The following results were obtained:1.The results showed that the leaf water content of Eucalyptus torelliana was the highest,which was 67.56%,followed by 65.94% of Eucalyptus 12 ABL W5.Leaf water content of the lowest for the Eucalyptus,followed by E.exserta F.V.Muell ×E.robusta Smith,water content were 47.49% and 47.54%.The highest water content of branches was 68.70% of Eucalyptus 12 ABL W5,followed by E.urophylla S.T.Blade × E.camaldulensis Dehnhardt LH22,which was 63.54%.The lowest water content of the branches is Eucalyptus citriodora Hook.f.,followed by Eucalyptus torelliana,the water content is 42.42% and 49.35% respectively.The yieldof leaves volatile oil of Eucalyptus citriodora Hook.f.was the highest,the yield was0.93%,followed by E.exserta F.V.Muell × E.robusta Smith,and the yield was0.84%.The lowest yield for Eucalyptus urophylla L9,volatile oil yield was 0.20%,followed by Eucalyptus exserta F.V.Muell.,volatile oil yield was 0.47%.The highest yield of branches volatile oil for E.exserta F.V.Muell × E.robusta Smith,the yield was 0.57%.The second highest rate of branches volatile oil for Eucalyptus citriodora Hook.f.,the yield was 0.53%.,The lowest yield for Eucalyptus urophylla L9,the yield was 0.05%,followed by Eucalyptus exserta F.V.Muell.the rate of volatile oil was 0.13%.2.The chemical constituents of the volatile oils of 18 kinds of plant materials were analyzed by gas chromatography-mass spectrometry(GC-MS),and the chemical constituents of the volatile oil were analyzed by steam distillation.18 kinds of volatile oil mainly by the hydrocarbons and alcohol compounds,mainly terpenoids.The relative percentage of hydrocarbons in the volatile oil is 13.16% ~ 82.24%,and the relative percentage of the alcohols is 14.27% ~ 73.64%.The two main components in the volatile oil are eucalyptol and ?-pinene.The number of compounds in leaves volatile oil was 38 ~ 96,and the number of compounds in branches volatile oil was 47 ~ 97.3.The inhibitory effects of 18 kinds of Eucalyptus volatile oil on Ralstonia solanacearum were determined by the MTT borth microdilution method.The results showed that nine kinds of Eucalyptus leaves and branches volatile oil had good inhibitory effect on the Ralstonia solanacearum,IC50 was 48.17±0.34 ~172.06±5.19mg/m L,and the positive control of streptomycin sulfate was 82.35±1.19 mg/m L.With an increase in the concentration of volatile oil,the inhibitory effect on Ralstonia solanacearum was increased.Among the nine kinds of Eucalyptus,the best inhibitory effect is Eucalyptus citriodora Hook.f.,the IC50 of the volatile oil of the leaves and the branches were 56.22 ± 0.63 ?g / m L and 48.17 ± 0.34 ?g / m L,respectively.The worst was E.urophylla S.T.Blade × E.camaldulensis Dehnhardt LH22,the IC50 values of the leaves and branches of volatile oil were 152.64 ± 2.58 ?g / m L and172.06 ± 5.19 ?g / m L,respectively.4.The activities of volatile oil in leaves and branches of Eucalyptus were significantly inhibited on Ralstonia solanacearum(Smith)Yabuuchi.There was no significant correlation between the IC50 values and the relative contents of aliphatic hydrocarbons,alcohols,eucalyptol and some main components.It means,the chemical action of plant volatile oil is a complex process that is caused by the interaction of major compounds and secondary compounds,does not work by some or several major compounds. |
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